run-tests: mechanism to report exceptions during test execution

Sometimes when running tests you introduce a ton of exceptions.
The most extreme example of this is running Mercurial with Python 3,
which currently spews thousands of exceptions when running the test
harness.

This commit adds an opt-in feature to run-tests.py to aggregate
exceptions encountered by `hg` when running tests.

When --exceptions is used, the test harness enables the
"logexceptions" extension in the test environment. This extension
wraps the Mercurial function to handle exceptions and writes
information about the exception to a random filename in a directory
defined by the test harness via an environment variable. At the
end of the test harness, these files are parsed, aggregated, and
a list of all unique Mercurial frames triggering exceptions is
printed in order of frequency.

This feature is intended to aid Python 3 development. I've only
really tested it on Python 3. There is no shortage of improvements
that could be made. e.g. we could write a separate file containing
the exception report - maybe even an HTML report. We also don't
capture which tests demonstrate the exceptions, so there's no turnkey
way to test whether a code change made an exception disappear.
Perfect is the enemy of good. I think the current patch is useful
enough to land. Whoever uses it can send patches to imprve its
usefulness.

Differential Revision: https://phab.mercurial-scm.org/D1477

tests/logexceptions.py

@@ -0,0 +1,73
+# logexceptions.py - Write files containing info about Mercurial exceptions
+#
+# Copyright 2017 Matt Mackall <[e-mail]>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from __future__ import absolute_import
+
+import inspect
+import os
+import sys
+import traceback
+import uuid
+
+from mercurial import (
+    dispatch,
+    extensions,
+)
+
+def handleexception(orig, ui):
+    res = orig(ui)
+
+    if not ui.environ.get(b'HGEXCEPTIONSDIR'):
+        return res
+
+    dest = os.path.join(ui.environ[b'HGEXCEPTIONSDIR'],
+                        str(uuid.uuid4()).encode('ascii'))
+
+    exc_type, exc_value, exc_tb = sys.exc_info()
+
+    stack = []
+    tb = exc_tb
+    while tb:
+        stack.append(tb)
+        tb = tb.tb_next
+    stack.reverse()
+
+    hgframe = 'unknown'
+    hgline = 'unknown'
+
+    # Find the first Mercurial frame in the stack.
+    for tb in stack:
+        mod = inspect.getmodule(tb)
+        if not mod.__name__.startswith(('hg', 'mercurial')):
+            continue
+
+        frame = tb.tb_frame
+
+        try:
+            with open(inspect.getsourcefile(tb), 'r') as fh:
+                hgline = fh.readlines()[frame.f_lineno - 1].strip()
+        except (IndexError, OSError):
+            pass
+
+        hgframe = '%s:%d' % (frame.f_code.co_filename, frame.f_lineno)
+        break
+
+    primary = traceback.extract_tb(exc_tb)[-1]
+    primaryframe = '%s:%d' % (primary.filename, primary.lineno)
+
+    with open(dest, 'wb') as fh:
+        parts = [
+            str(exc_value),
+            primaryframe,
+            hgframe,
+            hgline,
+        ]
+        fh.write(b'\0'.join(p.encode('utf-8', 'replace') for p in parts))
+
+def extsetup(ui):
+    extensions.wrapfunction(dispatch, 'handlecommandexception',
+                            handleexception)

.hgignore

@@ -1,67 +1,68
 syntax: glob
 
 *.elc
 *.tmp
 *.orig
 *.rej
 *~
 *.mergebackup
 *.o
 *.so
 *.dll
 *.exe
 *.pyd
 *.pyc
 *.pyo
 *$py.class
 *.swp
 *.prof
 *.zip
 \#*\#
 .\#*
 tests/.coverage*
 tests/.testtimes*
 tests/.hypothesis
 tests/hypothesis-generated
 tests/annotated
+tests/exceptions
 tests/*.err
 tests/htmlcov
 build
 contrib/chg/chg
 contrib/hgsh/hgsh
 contrib/vagrant/.vagrant
 contrib/docker/debian-*
 contrib/docker/ubuntu-*
 dist
 packages
 doc/common.txt
 doc/*.[0-9]
 doc/*.[0-9].txt
 doc/*.[0-9].gendoc.txt
 doc/*.[0-9].{x,ht}ml
 MANIFEST
 MANIFEST.in
 patches
 mercurial/__modulepolicy__.py
 mercurial/__version__.py
 mercurial/hgpythonlib.h
 mercurial.egg-info
 .DS_Store
 tags
 cscope.*
 .idea/*
 .asv/*
 i18n/hg.pot
 locale/*/LC_MESSAGES/hg.mo
 hgext/__index__.py
 
 # Generated wheels
 wheelhouse/
 
 syntax: regexp
 ^\.pc/
 ^\.(pydev)?project
 
 # hackable windows distribution additions
 ^hg-python
 ^hg.py$

tests/run-tests.py

@@ -1,2967 +1,3017
 #!/usr/bin/env python
 #
 # run-tests.py - Run a set of tests on Mercurial
 #
 # Copyright 2006 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 # Modifying this script is tricky because it has many modes:
 #   - serial (default) vs parallel (-jN, N > 1)
 #   - no coverage (default) vs coverage (-c, -C, -s)
 #   - temp install (default) vs specific hg script (--with-hg, --local)
 #   - tests are a mix of shell scripts and Python scripts
 #
 # If you change this script, it is recommended that you ensure you
 # haven't broken it by running it in various modes with a representative
 # sample of test scripts.  For example:
 #
 #  1) serial, no coverage, temp install:
 #      ./run-tests.py test-s*
 #  2) serial, no coverage, local hg:
 #      ./run-tests.py --local test-s*
 #  3) serial, coverage, temp install:
 #      ./run-tests.py -c test-s*
 #  4) serial, coverage, local hg:
 #      ./run-tests.py -c --local test-s*      # unsupported
 #  5) parallel, no coverage, temp install:
 #      ./run-tests.py -j2 test-s*
 #  6) parallel, no coverage, local hg:
 #      ./run-tests.py -j2 --local test-s*
 #  7) parallel, coverage, temp install:
 #      ./run-tests.py -j2 -c test-s*          # currently broken
 #  8) parallel, coverage, local install:
 #      ./run-tests.py -j2 -c --local test-s*  # unsupported (and broken)
 #  9) parallel, custom tmp dir:
 #      ./run-tests.py -j2 --tmpdir /tmp/myhgtests
 #  10) parallel, pure, tests that call run-tests:
 #      ./run-tests.py --pure `grep -l run-tests.py *.t`
 #
 # (You could use any subset of the tests: test-s* happens to match
 # enough that it's worth doing parallel runs, few enough that it
 # completes fairly quickly, includes both shell and Python scripts, and
 # includes some scripts that run daemon processes.)
 
 from __future__ import absolute_import, print_function
 
 import argparse
+import collections
 import difflib
 import distutils.version as version
 import errno
 import json
 import os
 import random
 import re
 import shutil
 import signal
 import socket
 import subprocess
 import sys
 import sysconfig
 import tempfile
 import threading
 import time
 import unittest
 import xml.dom.minidom as minidom
 
 try:
     import Queue as queue
 except ImportError:
     import queue
 
 try:
     import shlex
     shellquote = shlex.quote
 except (ImportError, AttributeError):
     import pipes
     shellquote = pipes.quote
 
 if os.environ.get('RTUNICODEPEDANTRY', False):
     try:
         reload(sys)
         sys.setdefaultencoding("undefined")
     except NameError:
         pass
 
 origenviron = os.environ.copy()
 osenvironb = getattr(os, 'environb', os.environ)
 processlock = threading.Lock()
 
 pygmentspresent = False
 # ANSI color is unsupported prior to Windows 10
 if os.name != 'nt':
     try: # is pygments installed
         import pygments
         import pygments.lexers as lexers
         import pygments.lexer as lexer
         import pygments.formatters as formatters
         import pygments.token as token
         import pygments.style as style
         pygmentspresent = True
         difflexer = lexers.DiffLexer()
         terminal256formatter = formatters.Terminal256Formatter()
     except ImportError:
         pass
 
 if pygmentspresent:
     class TestRunnerStyle(style.Style):
         default_style = ""
         skipped = token.string_to_tokentype("Token.Generic.Skipped")
         failed = token.string_to_tokentype("Token.Generic.Failed")
         skippedname = token.string_to_tokentype("Token.Generic.SName")
         failedname = token.string_to_tokentype("Token.Generic.FName")
         styles = {
             skipped:         '#e5e5e5',
             skippedname:     '#00ffff',
             failed:          '#7f0000',
             failedname:      '#ff0000',
         }
 
     class TestRunnerLexer(lexer.RegexLexer):
         tokens = {
             'root': [
                 (r'^Skipped', token.Generic.Skipped, 'skipped'),
                 (r'^Failed ', token.Generic.Failed, 'failed'),
                 (r'^ERROR: ', token.Generic.Failed, 'failed'),
             ],
             'skipped': [
                 (r'[\w-]+\.(t|py)', token.Generic.SName),
                 (r':.*', token.Generic.Skipped),
             ],
             'failed': [
                 (r'[\w-]+\.(t|py)', token.Generic.FName),
                 (r'(:| ).*', token.Generic.Failed),
             ]
         }
 
     runnerformatter = formatters.Terminal256Formatter(style=TestRunnerStyle)
     runnerlexer = TestRunnerLexer()
 
 if sys.version_info > (3, 5, 0):
     PYTHON3 = True
     xrange = range # we use xrange in one place, and we'd rather not use range
     def _bytespath(p):
         if p is None:
             return p
         return p.encode('utf-8')
 
     def _strpath(p):
         if p is None:
             return p
         return p.decode('utf-8')
 
 elif sys.version_info >= (3, 0, 0):
     print('%s is only supported on Python 3.5+ and 2.7, not %s' %
           (sys.argv[0], '.'.join(str(v) for v in sys.version_info[:3])))
     sys.exit(70) # EX_SOFTWARE from `man 3 sysexit`
 else:
     PYTHON3 = False
 
     # In python 2.x, path operations are generally done using
     # bytestrings by default, so we don't have to do any extra
     # fiddling there. We define the wrapper functions anyway just to
     # help keep code consistent between platforms.
     def _bytespath(p):
         return p
 
     _strpath = _bytespath
 
 # For Windows support
 wifexited = getattr(os, "WIFEXITED", lambda x: False)
 
 # Whether to use IPv6
 def checksocketfamily(name, port=20058):
     """return true if we can listen on localhost using family=name
 
     name should be either 'AF_INET', or 'AF_INET6'.
     port being used is okay - EADDRINUSE is considered as successful.
     """
     family = getattr(socket, name, None)
     if family is None:
         return False
     try:
         s = socket.socket(family, socket.SOCK_STREAM)
         s.bind(('localhost', port))
         s.close()
         return True
     except socket.error as exc:
         if exc.errno == errno.EADDRINUSE:
             return True
         elif exc.errno in (errno.EADDRNOTAVAIL, errno.EPROTONOSUPPORT):
             return False
         else:
             raise
     else:
         return False
 
 # useipv6 will be set by parseargs
 useipv6 = None
 
 def checkportisavailable(port):
     """return true if a port seems free to bind on localhost"""
     if useipv6:
         family = socket.AF_INET6
     else:
         family = socket.AF_INET
     try:
         s = socket.socket(family, socket.SOCK_STREAM)
         s.bind(('localhost', port))
         s.close()
         return True
     except socket.error as exc:
         if exc.errno not in (errno.EADDRINUSE, errno.EADDRNOTAVAIL,
                              errno.EPROTONOSUPPORT):
             raise
     return False
 
 closefds = os.name == 'posix'
 def Popen4(cmd, wd, timeout, env=None):
     processlock.acquire()
     p = subprocess.Popen(cmd, shell=True, bufsize=-1, cwd=wd, env=env,
                          close_fds=closefds,
                          stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                          stderr=subprocess.STDOUT)
     processlock.release()
 
     p.fromchild = p.stdout
     p.tochild = p.stdin
     p.childerr = p.stderr
 
     p.timeout = False
     if timeout:
         def t():
             start = time.time()
             while time.time() - start < timeout and p.returncode is None:
                 time.sleep(.1)
             p.timeout = True
             if p.returncode is None:
                 terminate(p)
         threading.Thread(target=t).start()
 
     return p
 
 PYTHON = _bytespath(sys.executable.replace('\\', '/'))
 IMPL_PATH = b'PYTHONPATH'
 if 'java' in sys.platform:
     IMPL_PATH = b'JYTHONPATH'
 
 defaults = {
     'jobs': ('HGTEST_JOBS', 1),
     'timeout': ('HGTEST_TIMEOUT', 180),
     'slowtimeout': ('HGTEST_SLOWTIMEOUT', 500),
     'port': ('HGTEST_PORT', 20059),
     'shell': ('HGTEST_SHELL', 'sh'),
 }
 
 def canonpath(path):
     return os.path.realpath(os.path.expanduser(path))
 
 def parselistfiles(files, listtype, warn=True):
     entries = dict()
     for filename in files:
         try:
             path = os.path.expanduser(os.path.expandvars(filename))
             f = open(path, "rb")
         except IOError as err:
             if err.errno != errno.ENOENT:
                 raise
             if warn:
                 print("warning: no such %s file: %s" % (listtype, filename))
             continue
 
         for line in f.readlines():
             line = line.split(b'#', 1)[0].strip()
             if line:
                 entries[line] = filename
 
         f.close()
     return entries
 
 def parsettestcases(path):
     """read a .t test file, return a set of test case names
 
     If path does not exist, return an empty set.
     """
     cases = set()
     try:
         with open(path, 'rb') as f:
             for l in f:
                 if l.startswith(b'#testcases '):
                     cases.update(l[11:].split())
     except IOError as ex:
         if ex.errno != errno.ENOENT:
             raise
     return cases
 
 def getparser():
     """Obtain the OptionParser used by the CLI."""
     parser = argparse.ArgumentParser(usage='%(prog)s [options] [tests]')
 
     selection = parser.add_argument_group('Test Selection')
     selection.add_argument('--allow-slow-tests', action='store_true',
         help='allow extremely slow tests')
     selection.add_argument("--blacklist", action="append",
         help="skip tests listed in the specified blacklist file")
     selection.add_argument("--changed",
         help="run tests that are changed in parent rev or working directory")
     selection.add_argument("-k", "--keywords",
         help="run tests matching keywords")
     selection.add_argument("-r", "--retest", action="store_true",
         help = "retest failed tests")
     selection.add_argument("--test-list", action="append",
         help="read tests to run from the specified file")
     selection.add_argument("--whitelist", action="append",
         help="always run tests listed in the specified whitelist file")
     selection.add_argument('tests', metavar='TESTS', nargs='*',
                         help='Tests to run')
 
     harness = parser.add_argument_group('Test Harness Behavior')
     harness.add_argument('--bisect-repo',
                         metavar='bisect_repo',
                         help=("Path of a repo to bisect. Use together with "
                               "--known-good-rev"))
     harness.add_argument("-d", "--debug", action="store_true",
         help="debug mode: write output of test scripts to console"
              " rather than capturing and diffing it (disables timeout)")
     harness.add_argument("-f", "--first", action="store_true",
         help="exit on the first test failure")
     harness.add_argument("-i", "--interactive", action="store_true",
         help="prompt to accept changed output")
     harness.add_argument("-j", "--jobs", type=int,
         help="number of jobs to run in parallel"
              " (default: $%s or %d)" % defaults['jobs'])
     harness.add_argument("--keep-tmpdir", action="store_true",
         help="keep temporary directory after running tests")
     harness.add_argument('--known-good-rev',
                         metavar="known_good_rev",
                         help=("Automatically bisect any failures using this "
                               "revision as a known-good revision."))
     harness.add_argument("--list-tests", action="store_true",
         help="list tests instead of running them")
     harness.add_argument("--loop", action="store_true",
         help="loop tests repeatedly")
     harness.add_argument('--random', action="store_true",
         help='run tests in random order')
     harness.add_argument("-p", "--port", type=int,
         help="port on which servers should listen"
              " (default: $%s or %d)" % defaults['port'])
     harness.add_argument('--profile-runner', action='store_true',
                         help='run statprof on run-tests')
     harness.add_argument("-R", "--restart", action="store_true",
         help="restart at last error")
     harness.add_argument("--runs-per-test", type=int, dest="runs_per_test",
         help="run each test N times (default=1)", default=1)
     harness.add_argument("--shell",
         help="shell to use (default: $%s or %s)" % defaults['shell'])
     harness.add_argument('--showchannels', action='store_true',
                         help='show scheduling channels')
     harness.add_argument("--slowtimeout", type=int,
         help="kill errant slow tests after SLOWTIMEOUT seconds"
              " (default: $%s or %d)" % defaults['slowtimeout'])
     harness.add_argument("-t", "--timeout", type=int,
         help="kill errant tests after TIMEOUT seconds"
              " (default: $%s or %d)" % defaults['timeout'])
     harness.add_argument("--tmpdir",
         help="run tests in the given temporary directory"
              " (implies --keep-tmpdir)")
     harness.add_argument("-v", "--verbose", action="store_true",
         help="output verbose messages")
 
     hgconf = parser.add_argument_group('Mercurial Configuration')
     hgconf.add_argument("--chg", action="store_true",
         help="install and use chg wrapper in place of hg")
     hgconf.add_argument("--compiler",
         help="compiler to build with")
-    hgconf.add_argument('--extra-config-opt', action="append",
+    hgconf.add_argument('--extra-config-opt', action="append", default=[],
         help='set the given config opt in the test hgrc')
     hgconf.add_argument("-l", "--local", action="store_true",
         help="shortcut for --with-hg=<testdir>/../hg, "
              "and --with-chg=<testdir>/../contrib/chg/chg if --chg is set")
     hgconf.add_argument("--ipv6", action="store_true",
         help="prefer IPv6 to IPv4 for network related tests")
     hgconf.add_argument("--pure", action="store_true",
         help="use pure Python code instead of C extensions")
     hgconf.add_argument("-3", "--py3k-warnings", action="store_true",
         help="enable Py3k warnings on Python 2.7+")
     hgconf.add_argument("--with-chg", metavar="CHG",
         help="use specified chg wrapper in place of hg")
     hgconf.add_argument("--with-hg",
         metavar="HG",
         help="test using specified hg script rather than a "
              "temporary installation")
     # This option should be deleted once test-check-py3-compat.t and other
     # Python 3 tests run with Python 3.
     hgconf.add_argument("--with-python3", metavar="PYTHON3",
         help="Python 3 interpreter (if running under Python 2)"
              " (TEMPORARY)")
 
     reporting = parser.add_argument_group('Results Reporting')
     reporting.add_argument("-C", "--annotate", action="store_true",
         help="output files annotated with coverage")
     reporting.add_argument("--color", choices=["always", "auto", "never"],
         default=os.environ.get('HGRUNTESTSCOLOR', 'auto'),
         help="colorisation: always|auto|never (default: auto)")
     reporting.add_argument("-c", "--cover", action="store_true",
         help="print a test coverage report")
+    reporting.add_argument('--exceptions', action='store_true',
+        help='log all exceptions and generate an exception report')
     reporting.add_argument("-H", "--htmlcov", action="store_true",
         help="create an HTML report of the coverage of the files")
     reporting.add_argument("--json", action="store_true",
         help="store test result data in 'report.json' file")
     reporting.add_argument("--outputdir",
         help="directory to write error logs to (default=test directory)")
     reporting.add_argument("-n", "--nodiff", action="store_true",
         help="skip showing test changes")
     reporting.add_argument("-S", "--noskips", action="store_true",
         help="don't report skip tests verbosely")
     reporting.add_argument("--time", action="store_true",
         help="time how long each test takes")
     reporting.add_argument("--view",
         help="external diff viewer")
     reporting.add_argument("--xunit",
         help="record xunit results at specified path")
 
     for option, (envvar, default) in defaults.items():
         defaults[option] = type(default)(os.environ.get(envvar, default))
     parser.set_defaults(**defaults)
 
     return parser
 
 def parseargs(args, parser):
     """Parse arguments with our OptionParser and validate results."""
     options = parser.parse_args(args)
 
     # jython is always pure
     if 'java' in sys.platform or '__pypy__' in sys.modules:
         options.pure = True
 
     if options.with_hg:
         options.with_hg = canonpath(_bytespath(options.with_hg))
         if not (os.path.isfile(options.with_hg) and
                 os.access(options.with_hg, os.X_OK)):
             parser.error('--with-hg must specify an executable hg script')
         if os.path.basename(options.with_hg) not in [b'hg', b'hg.exe']:
             sys.stderr.write('warning: --with-hg should specify an hg script\n')
     if options.local:
         testdir = os.path.dirname(_bytespath(canonpath(sys.argv[0])))
         reporootdir = os.path.dirname(testdir)
         pathandattrs = [(b'hg', 'with_hg')]
         if options.chg:
             pathandattrs.append((b'contrib/chg/chg', 'with_chg'))
         for relpath, attr in pathandattrs:
             binpath = os.path.join(reporootdir, relpath)
             if os.name != 'nt' and not os.access(binpath, os.X_OK):
                 parser.error('--local specified, but %r not found or '
                              'not executable' % binpath)
             setattr(options, attr, binpath)
 
     if (options.chg or options.with_chg) and os.name == 'nt':
         parser.error('chg does not work on %s' % os.name)
     if options.with_chg:
         options.chg = False  # no installation to temporary location
         options.with_chg = canonpath(_bytespath(options.with_chg))
         if not (os.path.isfile(options.with_chg) and
                 os.access(options.with_chg, os.X_OK)):
             parser.error('--with-chg must specify a chg executable')
     if options.chg and options.with_hg:
         # chg shares installation location with hg
         parser.error('--chg does not work when --with-hg is specified '
                      '(use --with-chg instead)')
 
     if options.color == 'always' and not pygmentspresent:
         sys.stderr.write('warning: --color=always ignored because '
                          'pygments is not installed\n')
 
     if options.bisect_repo and not options.known_good_rev:
         parser.error("--bisect-repo cannot be used without --known-good-rev")
 
     global useipv6
     if options.ipv6:
         useipv6 = checksocketfamily('AF_INET6')
     else:
         # only use IPv6 if IPv4 is unavailable and IPv6 is available
         useipv6 = ((not checksocketfamily('AF_INET'))
                    and checksocketfamily('AF_INET6'))
 
     options.anycoverage = options.cover or options.annotate or options.htmlcov
     if options.anycoverage:
         try:
             import coverage
             covver = version.StrictVersion(coverage.__version__).version
             if covver < (3, 3):
                 parser.error('coverage options require coverage 3.3 or later')
         except ImportError:
             parser.error('coverage options now require the coverage package')
 
     if options.anycoverage and options.local:
         # this needs some path mangling somewhere, I guess
         parser.error("sorry, coverage options do not work when --local "
                      "is specified")
 
     if options.anycoverage and options.with_hg:
         parser.error("sorry, coverage options do not work when --with-hg "
                      "is specified")
 
     global verbose
     if options.verbose:
         verbose = ''
 
     if options.tmpdir:
         options.tmpdir = canonpath(options.tmpdir)
 
     if options.jobs < 1:
         parser.error('--jobs must be positive')
     if options.interactive and options.debug:
         parser.error("-i/--interactive and -d/--debug are incompatible")
     if options.debug:
         if options.timeout != defaults['timeout']:
             sys.stderr.write(
                 'warning: --timeout option ignored with --debug\n')
         if options.slowtimeout != defaults['slowtimeout']:
             sys.stderr.write(
                 'warning: --slowtimeout option ignored with --debug\n')
         options.timeout = 0
         options.slowtimeout = 0
     if options.py3k_warnings:
         if PYTHON3:
             parser.error(
                 '--py3k-warnings can only be used on Python 2.7')
     if options.with_python3:
         if PYTHON3:
             parser.error('--with-python3 cannot be used when executing with '
                          'Python 3')
 
         options.with_python3 = canonpath(options.with_python3)
         # Verify Python3 executable is acceptable.
         proc = subprocess.Popen([options.with_python3, b'--version'],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT)
         out, _err = proc.communicate()
         ret = proc.wait()
         if ret != 0:
             parser.error('could not determine version of python 3')
         if not out.startswith('Python '):
             parser.error('unexpected output from python3 --version: %s' %
                          out)
         vers = version.LooseVersion(out[len('Python '):])
         if vers < version.LooseVersion('3.5.0'):
             parser.error('--with-python3 version must be 3.5.0 or greater; '
                          'got %s' % out)
 
     if options.blacklist:
         options.blacklist = parselistfiles(options.blacklist, 'blacklist')
     if options.whitelist:
         options.whitelisted = parselistfiles(options.whitelist, 'whitelist')
     else:
         options.whitelisted = {}
 
     if options.showchannels:
         options.nodiff = True
 
     return options
 
 def rename(src, dst):
     """Like os.rename(), trade atomicity and opened files friendliness
     for existing destination support.
     """
     shutil.copy(src, dst)
     os.remove(src)
 
 _unified_diff = difflib.unified_diff
 if PYTHON3:
     import functools
     _unified_diff = functools.partial(difflib.diff_bytes, difflib.unified_diff)
 
 def getdiff(expected, output, ref, err):
     servefail = False
     lines = []
     for line in _unified_diff(expected, output, ref, err):
         if line.startswith(b'+++') or line.startswith(b'---'):
             line = line.replace(b'\\', b'/')
             if line.endswith(b' \n'):
                 line = line[:-2] + b'\n'
         lines.append(line)
         if not servefail and line.startswith(
                              b'+  abort: child process failed to start'):
             servefail = True
 
     return servefail, lines
 
 verbose = False
 def vlog(*msg):
     """Log only when in verbose mode."""
     if verbose is False:
         return
 
     return log(*msg)
 
 # Bytes that break XML even in a CDATA block: control characters 0-31
 # sans \t, \n and \r
 CDATA_EVIL = re.compile(br"[\000-\010\013\014\016-\037]")
 
 # Match feature conditionalized output lines in the form, capturing the feature
 # list in group 2, and the preceeding line output in group 1:
 #
 #   output..output (feature !)\n
 optline = re.compile(b'(.*) \((.+?) !\)\n$')
 
 def cdatasafe(data):
     """Make a string safe to include in a CDATA block.
 
     Certain control characters are illegal in a CDATA block, and
     there's no way to include a ]]> in a CDATA either. This function
     replaces illegal bytes with ? and adds a space between the ]] so
     that it won't break the CDATA block.
     """
     return CDATA_EVIL.sub(b'?', data).replace(b']]>', b'] ]>')
 
 def log(*msg):
     """Log something to stdout.
 
     Arguments are strings to print.
     """
     with iolock:
         if verbose:
             print(verbose, end=' ')
         for m in msg:
             print(m, end=' ')
         print()
         sys.stdout.flush()
 
 def highlightdiff(line, color):
     if not color:
         return line
     assert pygmentspresent
     return pygments.highlight(line.decode('latin1'), difflexer,
                               terminal256formatter).encode('latin1')
 
 def highlightmsg(msg, color):
     if not color:
         return msg
     assert pygmentspresent
     return pygments.highlight(msg, runnerlexer, runnerformatter)
 
 def terminate(proc):
     """Terminate subprocess"""
     vlog('# Terminating process %d' % proc.pid)
     try:
         proc.terminate()
     except OSError:
         pass
 
 def killdaemons(pidfile):
     import killdaemons as killmod
     return killmod.killdaemons(pidfile, tryhard=False, remove=True,
                                logfn=vlog)
 
 class Test(unittest.TestCase):
     """Encapsulates a single, runnable test.
 
     While this class conforms to the unittest.TestCase API, it differs in that
     instances need to be instantiated manually. (Typically, unittest.TestCase
     classes are instantiated automatically by scanning modules.)
     """
 
     # Status code reserved for skipped tests (used by hghave).
     SKIPPED_STATUS = 80
 
     def __init__(self, path, outputdir, tmpdir, keeptmpdir=False,
                  debug=False,
                  timeout=None,
                  startport=None, extraconfigopts=None,
                  py3kwarnings=False, shell=None, hgcommand=None,
                  slowtimeout=None, usechg=False,
                  useipv6=False):
         """Create a test from parameters.
 
         path is the full path to the file defining the test.
 
         tmpdir is the main temporary directory to use for this test.
 
         keeptmpdir determines whether to keep the test's temporary directory
         after execution. It defaults to removal (False).
 
         debug mode will make the test execute verbosely, with unfiltered
         output.
 
         timeout controls the maximum run time of the test. It is ignored when
         debug is True. See slowtimeout for tests with #require slow.
 
         slowtimeout overrides timeout if the test has #require slow.
 
         startport controls the starting port number to use for this test. Each
         test will reserve 3 port numbers for execution. It is the caller's
         responsibility to allocate a non-overlapping port range to Test
         instances.
 
         extraconfigopts is an iterable of extra hgrc config options. Values
         must have the form "key=value" (something understood by hgrc). Values
         of the form "foo.key=value" will result in "[foo] key=value".
 
         py3kwarnings enables Py3k warnings.
 
         shell is the shell to execute tests in.
         """
         if timeout is None:
             timeout = defaults['timeout']
         if startport is None:
             startport = defaults['port']
         if slowtimeout is None:
             slowtimeout = defaults['slowtimeout']
         self.path = path
         self.bname = os.path.basename(path)
         self.name = _strpath(self.bname)
         self._testdir = os.path.dirname(path)
         self._outputdir = outputdir
         self._tmpname = os.path.basename(path)
         self.errpath = os.path.join(self._outputdir, b'%s.err' % self.bname)
 
         self._threadtmp = tmpdir
         self._keeptmpdir = keeptmpdir
         self._debug = debug
         self._timeout = timeout
         self._slowtimeout = slowtimeout
         self._startport = startport
         self._extraconfigopts = extraconfigopts or []
         self._py3kwarnings = py3kwarnings
         self._shell = _bytespath(shell)
         self._hgcommand = hgcommand or b'hg'
         self._usechg = usechg
         self._useipv6 = useipv6
 
         self._aborted = False
         self._daemonpids = []
         self._finished = None
         self._ret = None
         self._out = None
         self._skipped = None
         self._testtmp = None
         self._chgsockdir = None
 
         self._refout = self.readrefout()
 
     def readrefout(self):
         """read reference output"""
         # If we're not in --debug mode and reference output file exists,
         # check test output against it.
         if self._debug:
             return None # to match "out is None"
         elif os.path.exists(self.refpath):
             with open(self.refpath, 'rb') as f:
                 return f.read().splitlines(True)
         else:
             return []
 
     # needed to get base class __repr__ running
     @property
     def _testMethodName(self):
         return self.name
 
     def __str__(self):
         return self.name
 
     def shortDescription(self):
         return self.name
 
     def setUp(self):
         """Tasks to perform before run()."""
         self._finished = False
         self._ret = None
         self._out = None
         self._skipped = None
 
         try:
             os.mkdir(self._threadtmp)
         except OSError as e:
             if e.errno != errno.EEXIST:
                 raise
 
         name = self._tmpname
         self._testtmp = os.path.join(self._threadtmp, name)
         os.mkdir(self._testtmp)
 
         # Remove any previous output files.
         if os.path.exists(self.errpath):
             try:
                 os.remove(self.errpath)
             except OSError as e:
                 # We might have raced another test to clean up a .err
                 # file, so ignore ENOENT when removing a previous .err
                 # file.
                 if e.errno != errno.ENOENT:
                     raise
 
         if self._usechg:
             self._chgsockdir = os.path.join(self._threadtmp,
                                             b'%s.chgsock' % name)
             os.mkdir(self._chgsockdir)
 
     def run(self, result):
         """Run this test and report results against a TestResult instance."""
         # This function is extremely similar to unittest.TestCase.run(). Once
         # we require Python 2.7 (or at least its version of unittest), this
         # function can largely go away.
         self._result = result
         result.startTest(self)
         try:
             try:
                 self.setUp()
             except (KeyboardInterrupt, SystemExit):
                 self._aborted = True
                 raise
             except Exception:
                 result.addError(self, sys.exc_info())
                 return
 
             success = False
             try:
                 self.runTest()
             except KeyboardInterrupt:
                 self._aborted = True
                 raise
             except unittest.SkipTest as e:
                 result.addSkip(self, str(e))
                 # The base class will have already counted this as a
                 # test we "ran", but we want to exclude skipped tests
                 # from those we count towards those run.
                 result.testsRun -= 1
             except self.failureException as e:
                 # This differs from unittest in that we don't capture
                 # the stack trace. This is for historical reasons and
                 # this decision could be revisited in the future,
                 # especially for PythonTest instances.
                 if result.addFailure(self, str(e)):
                     success = True
             except Exception:
                 result.addError(self, sys.exc_info())
             else:
                 success = True
 
             try:
                 self.tearDown()
             except (KeyboardInterrupt, SystemExit):
                 self._aborted = True
                 raise
             except Exception:
                 result.addError(self, sys.exc_info())
                 success = False
 
             if success:
                 result.addSuccess(self)
         finally:
             result.stopTest(self, interrupted=self._aborted)
 
     def runTest(self):
         """Run this test instance.
 
         This will return a tuple describing the result of the test.
         """
         env = self._getenv()
         self._genrestoreenv(env)
         self._daemonpids.append(env['DAEMON_PIDS'])
         self._createhgrc(env['HGRCPATH'])
 
         vlog('# Test', self.name)
 
         ret, out = self._run(env)
         self._finished = True
         self._ret = ret
         self._out = out
 
         def describe(ret):
             if ret < 0:
                 return 'killed by signal: %d' % -ret
             return 'returned error code %d' % ret
 
         self._skipped = False
 
         if ret == self.SKIPPED_STATUS:
             if out is None: # Debug mode, nothing to parse.
                 missing = ['unknown']
                 failed = None
             else:
                 missing, failed = TTest.parsehghaveoutput(out)
 
             if not missing:
                 missing = ['skipped']
 
             if failed:
                 self.fail('hg have failed checking for %s' % failed[-1])
             else:
                 self._skipped = True
                 raise unittest.SkipTest(missing[-1])
         elif ret == 'timeout':
             self.fail('timed out')
         elif ret is False:
             self.fail('no result code from test')
         elif out != self._refout:
             # Diff generation may rely on written .err file.
             if (ret != 0 or out != self._refout) and not self._skipped \
                 and not self._debug:
                 f = open(self.errpath, 'wb')
                 for line in out:
                     f.write(line)
                 f.close()
 
             # The result object handles diff calculation for us.
             if self._result.addOutputMismatch(self, ret, out, self._refout):
                 # change was accepted, skip failing
                 return
 
             if ret:
                 msg = 'output changed and ' + describe(ret)
             else:
                 msg = 'output changed'
 
             self.fail(msg)
         elif ret:
             self.fail(describe(ret))
 
     def tearDown(self):
         """Tasks to perform after run()."""
         for entry in self._daemonpids:
             killdaemons(entry)
         self._daemonpids = []
 
         if self._keeptmpdir:
             log('\nKeeping testtmp dir: %s\nKeeping threadtmp dir: %s' %
                 (self._testtmp.decode('utf-8'),
                  self._threadtmp.decode('utf-8')))
         else:
             shutil.rmtree(self._testtmp, True)
             shutil.rmtree(self._threadtmp, True)
 
         if self._usechg:
             # chgservers will stop automatically after they find the socket
             # files are deleted
             shutil.rmtree(self._chgsockdir, True)
 
         if (self._ret != 0 or self._out != self._refout) and not self._skipped \
             and not self._debug and self._out:
             f = open(self.errpath, 'wb')
             for line in self._out:
                 f.write(line)
             f.close()
 
         vlog("# Ret was:", self._ret, '(%s)' % self.name)
 
     def _run(self, env):
         # This should be implemented in child classes to run tests.
         raise unittest.SkipTest('unknown test type')
 
     def abort(self):
         """Terminate execution of this test."""
         self._aborted = True
 
     def _portmap(self, i):
         offset = b'' if i == 0 else b'%d' % i
         return (br':%d\b' % (self._startport + i), b':$HGPORT%s' % offset)
 
     def _getreplacements(self):
         """Obtain a mapping of text replacements to apply to test output.
 
         Test output needs to be normalized so it can be compared to expected
         output. This function defines how some of that normalization will
         occur.
         """
         r = [
             # This list should be parallel to defineport in _getenv
             self._portmap(0),
             self._portmap(1),
             self._portmap(2),
             (br'(?m)^(saved backup bundle to .*\.hg)( \(glob\))?$',
              br'\1 (glob)'),
             (br'([^0-9])%s' % re.escape(self._localip()), br'\1$LOCALIP'),
             (br'\bHG_TXNID=TXN:[a-f0-9]{40}\b', br'HG_TXNID=TXN:$ID$'),
             ]
         r.append((self._escapepath(self._testtmp), b'$TESTTMP'))
 
         testdir = os.path.dirname(self.path)
         replacementfile = os.path.join(testdir, b'common-pattern.py')
 
         if os.path.exists(replacementfile):
             data = {}
             with open(replacementfile, mode='rb') as source:
                 # the intermediate 'compile' step help with debugging
                 code = compile(source.read(), replacementfile, 'exec')
                 exec(code, data)
                 r.extend(data.get('substitutions', ()))
         return r
 
     def _escapepath(self, p):
         if os.name == 'nt':
             return (
                 (b''.join(c.isalpha() and b'[%s%s]' % (c.lower(), c.upper()) or
                     c in b'/\\' and br'[/\\]' or c.isdigit() and c or b'\\' + c
                     for c in p))
             )
         else:
             return re.escape(p)
 
     def _localip(self):
         if self._useipv6:
             return b'::1'
         else:
             return b'127.0.0.1'
 
     def _genrestoreenv(self, testenv):
         """Generate a script that can be used by tests to restore the original
         environment."""
         # Put the restoreenv script inside self._threadtmp
         scriptpath = os.path.join(self._threadtmp, b'restoreenv.sh')
         testenv['HGTEST_RESTOREENV'] = scriptpath
 
         # Only restore environment variable names that the shell allows
         # us to export.
         name_regex = re.compile('^[a-zA-Z][a-zA-Z0-9_]*$')
 
         # Do not restore these variables; otherwise tests would fail.
         reqnames = {'PYTHON', 'TESTDIR', 'TESTTMP'}
 
         with open(scriptpath, 'w') as envf:
             for name, value in origenviron.items():
                 if not name_regex.match(name):
                     # Skip environment variables with unusual names not
                     # allowed by most shells.
                     continue
                 if name in reqnames:
                     continue
                 envf.write('%s=%s\n' % (name, shellquote(value)))
 
             for name in testenv:
                 if name in origenviron or name in reqnames:
                     continue
                 envf.write('unset %s\n' % (name,))
 
     def _getenv(self):
         """Obtain environment variables to use during test execution."""
         def defineport(i):
             offset = '' if i == 0 else '%s' % i
             env["HGPORT%s" % offset] = '%s' % (self._startport + i)
         env = os.environ.copy()
         env['PYTHONUSERBASE'] = sysconfig.get_config_var('userbase')
         env['HGEMITWARNINGS'] = '1'
         env['TESTTMP'] = self._testtmp
         env['HOME'] = self._testtmp
         # This number should match portneeded in _getport
         for port in xrange(3):
             # This list should be parallel to _portmap in _getreplacements
             defineport(port)
         env["HGRCPATH"] = os.path.join(self._threadtmp, b'.hgrc')
         env["DAEMON_PIDS"] = os.path.join(self._threadtmp, b'daemon.pids')
         env["HGEDITOR"] = ('"' + sys.executable + '"'
                            + ' -c "import sys; sys.exit(0)"')
         env["HGMERGE"] = "internal:merge"
         env["HGUSER"]   = "test"
         env["HGENCODING"] = "ascii"
         env["HGENCODINGMODE"] = "strict"
         env['HGIPV6'] = str(int(self._useipv6))
 
         # LOCALIP could be ::1 or 127.0.0.1. Useful for tests that require raw
         # IP addresses.
         env['LOCALIP'] = self._localip()
 
         # Reset some environment variables to well-known values so that
         # the tests produce repeatable output.
         env['LANG'] = env['LC_ALL'] = env['LANGUAGE'] = 'C'
         env['TZ'] = 'GMT'
         env["EMAIL"] = "Foo Bar <[e-mail]>"
         env['COLUMNS'] = '80'
         env['TERM'] = 'xterm'
 
         for k in ('HG HGPROF CDPATH GREP_OPTIONS http_proxy no_proxy ' +
                   'HGPLAIN HGPLAINEXCEPT EDITOR VISUAL PAGER ' +
                   'NO_PROXY CHGDEBUG').split():
             if k in env:
                 del env[k]
 
         # unset env related to hooks
         for k in env.keys():
             if k.startswith('HG_'):
                 del env[k]
 
         if self._usechg:
             env['CHGSOCKNAME'] = os.path.join(self._chgsockdir, b'server')
 
         return env
 
     def _createhgrc(self, path):
         """Create an hgrc file for this test."""
         hgrc = open(path, 'wb')
         hgrc.write(b'[ui]\n')
         hgrc.write(b'slash = True\n')
         hgrc.write(b'interactive = False\n')
         hgrc.write(b'mergemarkers = detailed\n')
         hgrc.write(b'promptecho = True\n')
         hgrc.write(b'[defaults]\n')
         hgrc.write(b'[devel]\n')
         hgrc.write(b'all-warnings = true\n')
         hgrc.write(b'default-date = 0 0\n')
         hgrc.write(b'[largefiles]\n')
         hgrc.write(b'usercache = %s\n' %
                    (os.path.join(self._testtmp, b'.cache/largefiles')))
         hgrc.write(b'[web]\n')
         hgrc.write(b'address = localhost\n')
         hgrc.write(b'ipv6 = %s\n' % str(self._useipv6).encode('ascii'))
 
         for opt in self._extraconfigopts:
             section, key = opt.encode('utf-8').split(b'.', 1)
             assert b'=' in key, ('extra config opt %s must '
                                  'have an = for assignment' % opt)
             hgrc.write(b'[%s]\n%s\n' % (section, key))
         hgrc.close()
 
     def fail(self, msg):
         # unittest differentiates between errored and failed.
         # Failed is denoted by AssertionError (by default at least).
         raise AssertionError(msg)
 
     def _runcommand(self, cmd, env, normalizenewlines=False):
         """Run command in a sub-process, capturing the output (stdout and
         stderr).
 
         Return a tuple (exitcode, output). output is None in debug mode.
         """
         if self._debug:
             proc = subprocess.Popen(cmd, shell=True, cwd=self._testtmp,
                                     env=env)
             ret = proc.wait()
             return (ret, None)
 
         proc = Popen4(cmd, self._testtmp, self._timeout, env)
         def cleanup():
             terminate(proc)
             ret = proc.wait()
             if ret == 0:
                 ret = signal.SIGTERM << 8
             killdaemons(env['DAEMON_PIDS'])
             return ret
 
         output = ''
         proc.tochild.close()
 
         try:
             output = proc.fromchild.read()
         except KeyboardInterrupt:
             vlog('# Handling keyboard interrupt')
             cleanup()
             raise
 
         ret = proc.wait()
         if wifexited(ret):
             ret = os.WEXITSTATUS(ret)
 
         if proc.timeout:
             ret = 'timeout'
 
         if ret:
             killdaemons(env['DAEMON_PIDS'])
 
         for s, r in self._getreplacements():
             output = re.sub(s, r, output)
 
         if normalizenewlines:
             output = output.replace('\r\n', '\n')
 
         return ret, output.splitlines(True)
 
 class PythonTest(Test):
     """A Python-based test."""
 
     @property
     def refpath(self):
         return os.path.join(self._testdir, b'%s.out' % self.bname)
 
     def _run(self, env):
         py3kswitch = self._py3kwarnings and b' -3' or b''
         cmd = b'%s%s "%s"' % (PYTHON, py3kswitch, self.path)
         vlog("# Running", cmd)
         normalizenewlines = os.name == 'nt'
         result = self._runcommand(cmd, env,
                                   normalizenewlines=normalizenewlines)
         if self._aborted:
             raise KeyboardInterrupt()
 
         return result
 
 # Some glob patterns apply only in some circumstances, so the script
 # might want to remove (glob) annotations that otherwise should be
 # retained.
 checkcodeglobpats = [
     # On Windows it looks like \ doesn't require a (glob), but we know
     # better.
     re.compile(br'^pushing to \$TESTTMP/.*[^)]$'),
     re.compile(br'^moving \S+/.*[^)]$'),
     re.compile(br'^pulling from \$TESTTMP/.*[^)]$'),
     # Not all platforms have 127.0.0.1 as loopback (though most do),
     # so we always glob that too.
     re.compile(br'.*\$LOCALIP.*$'),
 ]
 
 bchr = chr
 if PYTHON3:
     bchr = lambda x: bytes([x])
 
 class TTest(Test):
     """A "t test" is a test backed by a .t file."""
 
     SKIPPED_PREFIX = b'skipped: '
     FAILED_PREFIX = b'hghave check failed: '
     NEEDESCAPE = re.compile(br'[\x00-\x08\x0b-\x1f\x7f-\xff]').search
 
     ESCAPESUB = re.compile(br'[\x00-\x08\x0b-\x1f\\\x7f-\xff]').sub
     ESCAPEMAP = dict((bchr(i), br'\x%02x' % i) for i in range(256))
     ESCAPEMAP.update({b'\\': b'\\\\', b'\r': br'\r'})
 
     def __init__(self, path, *args, **kwds):
         # accept an extra "case" parameter
         case = None
         if 'case' in kwds:
             case = kwds.pop('case')
         self._case = case
         self._allcases = parsettestcases(path)
         super(TTest, self).__init__(path, *args, **kwds)
         if case:
             self.name = '%s (case %s)' % (self.name, _strpath(case))
             self.errpath = b'%s.%s.err' % (self.errpath[:-4], case)
             self._tmpname += b'-%s' % case
 
     @property
     def refpath(self):
         return os.path.join(self._testdir, self.bname)
 
     def _run(self, env):
         f = open(self.path, 'rb')
         lines = f.readlines()
         f.close()
 
         # .t file is both reference output and the test input, keep reference
         # output updated with the the test input. This avoids some race
         # conditions where the reference output does not match the actual test.
         if self._refout is not None:
             self._refout = lines
 
         salt, script, after, expected = self._parsetest(lines)
 
         # Write out the generated script.
         fname = b'%s.sh' % self._testtmp
         f = open(fname, 'wb')
         for l in script:
             f.write(l)
         f.close()
 
         cmd = b'%s "%s"' % (self._shell, fname)
         vlog("# Running", cmd)
 
         exitcode, output = self._runcommand(cmd, env)
 
         if self._aborted:
             raise KeyboardInterrupt()
 
         # Do not merge output if skipped. Return hghave message instead.
         # Similarly, with --debug, output is None.
         if exitcode == self.SKIPPED_STATUS or output is None:
             return exitcode, output
 
         return self._processoutput(exitcode, output, salt, after, expected)
 
     def _hghave(self, reqs):
         # TODO do something smarter when all other uses of hghave are gone.
         runtestdir = os.path.abspath(os.path.dirname(_bytespath(__file__)))
         tdir = runtestdir.replace(b'\\', b'/')
         proc = Popen4(b'%s -c "%s/hghave %s"' %
                       (self._shell, tdir, b' '.join(reqs)),
                       self._testtmp, 0, self._getenv())
         stdout, stderr = proc.communicate()
         ret = proc.wait()
         if wifexited(ret):
             ret = os.WEXITSTATUS(ret)
         if ret == 2:
             print(stdout.decode('utf-8'))
             sys.exit(1)
 
         if ret != 0:
             return False, stdout
 
         if b'slow' in reqs:
             self._timeout = self._slowtimeout
         return True, None
 
     def _iftest(self, args):
         # implements "#if"
         reqs = []
         for arg in args:
             if arg.startswith(b'no-') and arg[3:] in self._allcases:
                 if arg[3:] == self._case:
                     return False
             elif arg in self._allcases:
                 if arg != self._case:
                     return False
             else:
                 reqs.append(arg)
         return self._hghave(reqs)[0]
 
     def _parsetest(self, lines):
         # We generate a shell script which outputs unique markers to line
         # up script results with our source. These markers include input
         # line number and the last return code.
         salt = b"SALT%d" % time.time()
         def addsalt(line, inpython):
             if inpython:
                 script.append(b'%s %d 0\n' % (salt, line))
             else:
                 script.append(b'echo %s %d $?\n' % (salt, line))
 
         script = []
 
         # After we run the shell script, we re-unify the script output
         # with non-active parts of the source, with synchronization by our
         # SALT line number markers. The after table contains the non-active
         # components, ordered by line number.
         after = {}
 
         # Expected shell script output.
         expected = {}
 
         pos = prepos = -1
 
         # True or False when in a true or false conditional section
         skipping = None
 
         # We keep track of whether or not we're in a Python block so we
         # can generate the surrounding doctest magic.
         inpython = False
 
         if self._debug:
             script.append(b'set -x\n')
         if self._hgcommand != b'hg':
             script.append(b'alias hg="%s"\n' % self._hgcommand)
         if os.getenv('MSYSTEM'):
             script.append(b'alias pwd="pwd -W"\n')
 
         n = 0
         for n, l in enumerate(lines):
             if not l.endswith(b'\n'):
                 l += b'\n'
             if l.startswith(b'#require'):
                 lsplit = l.split()
                 if len(lsplit) < 2 or lsplit[0] != b'#require':
                     after.setdefault(pos, []).append('  !!! invalid #require\n')
                 haveresult, message = self._hghave(lsplit[1:])
                 if not haveresult:
                     script = [b'echo "%s"\nexit 80\n' % message]
                     break
                 after.setdefault(pos, []).append(l)
             elif l.startswith(b'#if'):
                 lsplit = l.split()
                 if len(lsplit) < 2 or lsplit[0] != b'#if':
                     after.setdefault(pos, []).append('  !!! invalid #if\n')
                 if skipping is not None:
                     after.setdefault(pos, []).append('  !!! nested #if\n')
                 skipping = not self._iftest(lsplit[1:])
                 after.setdefault(pos, []).append(l)
             elif l.startswith(b'#else'):
                 if skipping is None:
                     after.setdefault(pos, []).append('  !!! missing #if\n')
                 skipping = not skipping
                 after.setdefault(pos, []).append(l)
             elif l.startswith(b'#endif'):
                 if skipping is None:
                     after.setdefault(pos, []).append('  !!! missing #if\n')
                 skipping = None
                 after.setdefault(pos, []).append(l)
             elif skipping:
                 after.setdefault(pos, []).append(l)
             elif l.startswith(b'  >>> '): # python inlines
                 after.setdefault(pos, []).append(l)
                 prepos = pos
                 pos = n
                 if not inpython:
                     # We've just entered a Python block. Add the header.
                     inpython = True
                     addsalt(prepos, False) # Make sure we report the exit code.
                     script.append(b'%s -m heredoctest <<EOF\n' % PYTHON)
                 addsalt(n, True)
                 script.append(l[2:])
             elif l.startswith(b'  ... '): # python inlines
                 after.setdefault(prepos, []).append(l)
                 script.append(l[2:])
             elif l.startswith(b'  $ '): # commands
                 if inpython:
                     script.append(b'EOF\n')
                     inpython = False
                 after.setdefault(pos, []).append(l)
                 prepos = pos
                 pos = n
                 addsalt(n, False)
                 cmd = l[4:].split()
                 if len(cmd) == 2 and cmd[0] == b'cd':
                     l = b'  $ cd %s || exit 1\n' % cmd[1]
                 script.append(l[4:])
             elif l.startswith(b'  > '): # continuations
                 after.setdefault(prepos, []).append(l)
                 script.append(l[4:])
             elif l.startswith(b'  '): # results
                 # Queue up a list of expected results.
                 expected.setdefault(pos, []).append(l[2:])
             else:
                 if inpython:
                     script.append(b'EOF\n')
                     inpython = False
                 # Non-command/result. Queue up for merged output.
                 after.setdefault(pos, []).append(l)
 
         if inpython:
             script.append(b'EOF\n')
         if skipping is not None:
             after.setdefault(pos, []).append('  !!! missing #endif\n')
         addsalt(n + 1, False)
 
         return salt, script, after, expected
 
     def _processoutput(self, exitcode, output, salt, after, expected):
         # Merge the script output back into a unified test.
         warnonly = 1 # 1: not yet; 2: yes; 3: for sure not
         if exitcode != 0:
             warnonly = 3
 
         pos = -1
         postout = []
         for l in output:
             lout, lcmd = l, None
             if salt in l:
                 lout, lcmd = l.split(salt, 1)
 
             while lout:
                 if not lout.endswith(b'\n'):
                     lout += b' (no-eol)\n'
 
                 # Find the expected output at the current position.
                 els = [None]
                 if expected.get(pos, None):
                     els = expected[pos]
 
                 i = 0
                 optional = []
                 while i < len(els):
                     el = els[i]
 
                     r = self.linematch(el, lout)
                     if isinstance(r, str):
                         if r == '+glob':
                             lout = el[:-1] + ' (glob)\n'
                             r = '' # Warn only this line.
                         elif r == '-glob':
                             lout = ''.join(el.rsplit(' (glob)', 1))
                             r = '' # Warn only this line.
                         elif r == "retry":
                             postout.append(b'  ' + el)
                             els.pop(i)
                             break
                         else:
                             log('\ninfo, unknown linematch result: %r\n' % r)
                             r = False
                     if r:
                         els.pop(i)
                         break
                     if el:
                         if el.endswith(b" (?)\n"):
                             optional.append(i)
                         else:
                             m = optline.match(el)
                             if m:
                                 conditions = [
                                     c for c in m.group(2).split(b' ')]
 
                                 if not self._iftest(conditions):
                                     optional.append(i)
 
                     i += 1
 
                 if r:
                     if r == "retry":
                         continue
                     # clean up any optional leftovers
                     for i in optional:
                         postout.append(b'  ' + els[i])
                     for i in reversed(optional):
                         del els[i]
                     postout.append(b'  ' + el)
                 else:
                     if self.NEEDESCAPE(lout):
                         lout = TTest._stringescape(b'%s (esc)\n' %
                                                    lout.rstrip(b'\n'))
                     postout.append(b'  ' + lout) # Let diff deal with it.
                     if r != '': # If line failed.
                         warnonly = 3 # for sure not
                     elif warnonly == 1: # Is "not yet" and line is warn only.
                         warnonly = 2 # Yes do warn.
                 break
             else:
                 # clean up any optional leftovers
                 while expected.get(pos, None):
                     el = expected[pos].pop(0)
                     if el:
                         if not el.endswith(b" (?)\n"):
                             m = optline.match(el)
                             if m:
                                 conditions = [c for c in m.group(2).split(b' ')]
 
                                 if self._iftest(conditions):
                                     # Don't append as optional line
                                     continue
                             else:
                                 continue
                     postout.append(b'  ' + el)
 
             if lcmd:
                 # Add on last return code.
                 ret = int(lcmd.split()[1])
                 if ret != 0:
                     postout.append(b'  [%d]\n' % ret)
                 if pos in after:
                     # Merge in non-active test bits.
                     postout += after.pop(pos)
                 pos = int(lcmd.split()[0])
 
         if pos in after:
             postout += after.pop(pos)
 
         if warnonly == 2:
             exitcode = False # Set exitcode to warned.
 
         return exitcode, postout
 
     @staticmethod
     def rematch(el, l):
         try:
             el = b'(?:' + el + b')'
             # use \Z to ensure that the regex matches to the end of the string
             if os.name == 'nt':
                 return re.match(el + br'\r?\n\Z', l)
             return re.match(el + br'\n\Z', l)
         except re.error:
             # el is an invalid regex
             return False
 
     @staticmethod
     def globmatch(el, l):
         # The only supported special characters are * and ? plus / which also
         # matches \ on windows. Escaping of these characters is supported.
         if el + b'\n' == l:
             if os.altsep:
                 # matching on "/" is not needed for this line
                 for pat in checkcodeglobpats:
                     if pat.match(el):
                         return True
                 return b'-glob'
             return True
         el = el.replace(b'$LOCALIP', b'*')
         i, n = 0, len(el)
         res = b''
         while i < n:
             c = el[i:i + 1]
             i += 1
             if c == b'\\' and i < n and el[i:i + 1] in b'*?\\/':
                 res += el[i - 1:i + 1]
                 i += 1
             elif c == b'*':
                 res += b'.*'
             elif c == b'?':
                 res += b'.'
             elif c == b'/' and os.altsep:
                 res += b'[/\\\\]'
             else:
                 res += re.escape(c)
         return TTest.rematch(res, l)
 
     def linematch(self, el, l):
         retry = False
         if el == l: # perfect match (fast)
             return True
         if el:
             if el.endswith(b" (?)\n"):
                 retry = "retry"
                 el = el[:-5] + b"\n"
             else:
                 m = optline.match(el)
                 if m:
                     conditions = [c for c in m.group(2).split(b' ')]
 
                     el = m.group(1) + b"\n"
                     if not self._iftest(conditions):
                         retry = "retry"    # Not required by listed features
 
             if el.endswith(b" (esc)\n"):
                 if PYTHON3:
                     el = el[:-7].decode('unicode_escape') + '\n'
                     el = el.encode('utf-8')
                 else:
                     el = el[:-7].decode('string-escape') + '\n'
             if el == l or os.name == 'nt' and el[:-1] + b'\r\n' == l:
                 return True
             if el.endswith(b" (re)\n"):
                 return TTest.rematch(el[:-6], l) or retry
             if el.endswith(b" (glob)\n"):
                 # ignore '(glob)' added to l by 'replacements'
                 if l.endswith(b" (glob)\n"):
                     l = l[:-8] + b"\n"
                 return TTest.globmatch(el[:-8], l) or retry
             if os.altsep and l.replace(b'\\', b'/') == el:
                 return b'+glob'
         return retry
 
     @staticmethod
     def parsehghaveoutput(lines):
         '''Parse hghave log lines.
 
         Return tuple of lists (missing, failed):
           * the missing/unknown features
           * the features for which existence check failed'''
         missing = []
         failed = []
         for line in lines:
             if line.startswith(TTest.SKIPPED_PREFIX):
                 line = line.splitlines()[0]
                 missing.append(line[len(TTest.SKIPPED_PREFIX):].decode('utf-8'))
             elif line.startswith(TTest.FAILED_PREFIX):
                 line = line.splitlines()[0]
                 failed.append(line[len(TTest.FAILED_PREFIX):].decode('utf-8'))
 
         return missing, failed
 
     @staticmethod
     def _escapef(m):
         return TTest.ESCAPEMAP[m.group(0)]
 
     @staticmethod
     def _stringescape(s):
         return TTest.ESCAPESUB(TTest._escapef, s)
 
 iolock = threading.RLock()
 
 class TestResult(unittest._TextTestResult):
     """Holds results when executing via unittest."""
     # Don't worry too much about accessing the non-public _TextTestResult.
     # It is relatively common in Python testing tools.
     def __init__(self, options, *args, **kwargs):
         super(TestResult, self).__init__(*args, **kwargs)
 
         self._options = options
 
         # unittest.TestResult didn't have skipped until 2.7. We need to
         # polyfill it.
         self.skipped = []
 
         # We have a custom "ignored" result that isn't present in any Python
         # unittest implementation. It is very similar to skipped. It may make
         # sense to map it into skip some day.
         self.ignored = []
 
         self.times = []
         self._firststarttime = None
         # Data stored for the benefit of generating xunit reports.
         self.successes = []
         self.faildata = {}
 
         if options.color == 'auto':
             self.color = pygmentspresent and self.stream.isatty()
         elif options.color == 'never':
             self.color = False
         else: # 'always', for testing purposes
             self.color = pygmentspresent
 
     def addFailure(self, test, reason):
         self.failures.append((test, reason))
 
         if self._options.first:
             self.stop()
         else:
             with iolock:
                 if reason == "timed out":
                     self.stream.write('t')
                 else:
                     if not self._options.nodiff:
                         self.stream.write('\n')
                         # Exclude the '\n' from highlighting to lex correctly
                         formatted = 'ERROR: %s output changed\n' % test
                         self.stream.write(highlightmsg(formatted, self.color))
                     self.stream.write('!')
 
                 self.stream.flush()
 
     def addSuccess(self, test):
         with iolock:
             super(TestResult, self).addSuccess(test)
         self.successes.append(test)
 
     def addError(self, test, err):
         super(TestResult, self).addError(test, err)
         if self._options.first:
             self.stop()
 
     # Polyfill.
     def addSkip(self, test, reason):
         self.skipped.append((test, reason))
         with iolock:
             if self.showAll:
                 self.stream.writeln('skipped %s' % reason)
             else:
                 self.stream.write('s')
                 self.stream.flush()
 
     def addIgnore(self, test, reason):
         self.ignored.append((test, reason))
         with iolock:
             if self.showAll:
                 self.stream.writeln('ignored %s' % reason)
             else:
                 if reason not in ('not retesting', "doesn't match keyword"):
                     self.stream.write('i')
                 else:
                     self.testsRun += 1
                 self.stream.flush()
 
     def addOutputMismatch(self, test, ret, got, expected):
         """Record a mismatch in test output for a particular test."""
         if self.shouldStop:
             # don't print, some other test case already failed and
             # printed, we're just stale and probably failed due to our
             # temp dir getting cleaned up.
             return
 
         accepted = False
         lines = []
 
         with iolock:
             if self._options.nodiff:
                 pass
             elif self._options.view:
                 v = self._options.view
                 if PYTHON3:
                     v = _bytespath(v)
                 os.system(b"%s %s %s" %
                           (v, test.refpath, test.errpath))
             else:
                 servefail, lines = getdiff(expected, got,
                                            test.refpath, test.errpath)
                 if servefail:
                     raise test.failureException(
                         'server failed to start (HGPORT=%s)' % test._startport)
                 else:
                     self.stream.write('\n')
                     for line in lines:
                         line = highlightdiff(line, self.color)
                         if PYTHON3:
                             self.stream.flush()
                             self.stream.buffer.write(line)
                             self.stream.buffer.flush()
                         else:
                             self.stream.write(line)
                             self.stream.flush()
 
             # handle interactive prompt without releasing iolock
             if self._options.interactive:
                 if test.readrefout() != expected:
                     self.stream.write(
                         'Reference output has changed (run again to prompt '
                         'changes)')
                 else:
                     self.stream.write('Accept this change? [n] ')
                     answer = sys.stdin.readline().strip()
                     if answer.lower() in ('y', 'yes'):
                         if test.path.endswith(b'.t'):
                             rename(test.errpath, test.path)
                         else:
                             rename(test.errpath, '%s.out' % test.path)
                         accepted = True
             if not accepted:
                 self.faildata[test.name] = b''.join(lines)
 
         return accepted
 
     def startTest(self, test):
         super(TestResult, self).startTest(test)
 
         # os.times module computes the user time and system time spent by
         # child's processes along with real elapsed time taken by a process.
         # This module has one limitation. It can only work for Linux user
         # and not for Windows.
         test.started = os.times()
         if self._firststarttime is None: # thread racy but irrelevant
             self._firststarttime = test.started[4]
 
     def stopTest(self, test, interrupted=False):
         super(TestResult, self).stopTest(test)
 
         test.stopped = os.times()
 
         starttime = test.started
         endtime = test.stopped
         origin = self._firststarttime
         self.times.append((test.name,
                            endtime[2] - starttime[2], # user space CPU time
                            endtime[3] - starttime[3], # sys  space CPU time
                            endtime[4] - starttime[4], # real time
                            starttime[4] - origin, # start date in run context
                            endtime[4] - origin, # end date in run context
                            ))
 
         if interrupted:
             with iolock:
                 self.stream.writeln('INTERRUPTED: %s (after %d seconds)' % (
                     test.name, self.times[-1][3]))
 
 class TestSuite(unittest.TestSuite):
     """Custom unittest TestSuite that knows how to execute Mercurial tests."""
 
     def __init__(self, testdir, jobs=1, whitelist=None, blacklist=None,
                  retest=False, keywords=None, loop=False, runs_per_test=1,
                  loadtest=None, showchannels=False,
                  *args, **kwargs):
         """Create a new instance that can run tests with a configuration.
 
         testdir specifies the directory where tests are executed from. This
         is typically the ``tests`` directory from Mercurial's source
         repository.
 
         jobs specifies the number of jobs to run concurrently. Each test
         executes on its own thread. Tests actually spawn new processes, so
         state mutation should not be an issue.
 
         If there is only one job, it will use the main thread.
 
         whitelist and blacklist denote tests that have been whitelisted and
         blacklisted, respectively. These arguments don't belong in TestSuite.
         Instead, whitelist and blacklist should be handled by the thing that
         populates the TestSuite with tests. They are present to preserve
         backwards compatible behavior which reports skipped tests as part
         of the results.
 
         retest denotes whether to retest failed tests. This arguably belongs
         outside of TestSuite.
 
         keywords denotes key words that will be used to filter which tests
         to execute. This arguably belongs outside of TestSuite.
 
         loop denotes whether to loop over tests forever.
         """
         super(TestSuite, self).__init__(*args, **kwargs)
 
         self._jobs = jobs
         self._whitelist = whitelist
         self._blacklist = blacklist
         self._retest = retest
         self._keywords = keywords
         self._loop = loop
         self._runs_per_test = runs_per_test
         self._loadtest = loadtest
         self._showchannels = showchannels
 
     def run(self, result):
         # We have a number of filters that need to be applied. We do this
         # here instead of inside Test because it makes the running logic for
         # Test simpler.
         tests = []
         num_tests = [0]
         for test in self._tests:
             def get():
                 num_tests[0] += 1
                 if getattr(test, 'should_reload', False):
                     return self._loadtest(test, num_tests[0])
                 return test
             if not os.path.exists(test.path):
                 result.addSkip(test, "Doesn't exist")
                 continue
 
             if not (self._whitelist and test.bname in self._whitelist):
                 if self._blacklist and test.bname in self._blacklist:
                     result.addSkip(test, 'blacklisted')
                     continue
 
                 if self._retest and not os.path.exists(test.errpath):
                     result.addIgnore(test, 'not retesting')
                     continue
 
                 if self._keywords:
                     f = open(test.path, 'rb')
                     t = f.read().lower() + test.bname.lower()
                     f.close()
                     ignored = False
                     for k in self._keywords.lower().split():
                         if k not in t:
                             result.addIgnore(test, "doesn't match keyword")
                             ignored = True
                             break
 
                     if ignored:
                         continue
             for _ in xrange(self._runs_per_test):
                 tests.append(get())
 
         runtests = list(tests)
         done = queue.Queue()
         running = 0
 
         channels = [""] * self._jobs
 
         def job(test, result):
             for n, v in enumerate(channels):
                 if not v:
                     channel = n
                     break
             else:
                 raise ValueError('Could not find output channel')
             channels[channel] = "=" + test.name[5:].split(".")[0]
             try:
                 test(result)
                 done.put(None)
             except KeyboardInterrupt:
                 pass
             except: # re-raises
                 done.put(('!', test, 'run-test raised an error, see traceback'))
                 raise
             finally:
                 try:
                     channels[channel] = ''
                 except IndexError:
                     pass
 
         def stat():
             count = 0
             while channels:
                 d = '\n%03s  ' % count
                 for n, v in enumerate(channels):
                     if v:
                         d += v[0]
                         channels[n] = v[1:] or '.'
                     else:
                         d += ' '
                     d += ' '
                 with iolock:
                     sys.stdout.write(d + '  ')
                     sys.stdout.flush()
                 for x in xrange(10):
                     if channels:
                         time.sleep(.1)
                 count += 1
 
         stoppedearly = False
 
         if self._showchannels:
             statthread = threading.Thread(target=stat, name="stat")
             statthread.start()
 
         try:
             while tests or running:
                 if not done.empty() or running == self._jobs or not tests:
                     try:
                         done.get(True, 1)
                         running -= 1
                         if result and result.shouldStop:
                             stoppedearly = True
                             break
                     except queue.Empty:
                         continue
                 if tests and not running == self._jobs:
                     test = tests.pop(0)
                     if self._loop:
                         if getattr(test, 'should_reload', False):
                             num_tests[0] += 1
                             tests.append(
                                 self._loadtest(test, num_tests[0]))
                         else:
                             tests.append(test)
                     if self._jobs == 1:
                         job(test, result)
                     else:
                         t = threading.Thread(target=job, name=test.name,
                                              args=(test, result))
                         t.start()
                     running += 1
 
             # If we stop early we still need to wait on started tests to
             # finish. Otherwise, there is a race between the test completing
             # and the test's cleanup code running. This could result in the
             # test reporting incorrect.
             if stoppedearly:
                 while running:
                     try:
                         done.get(True, 1)
                         running -= 1
                     except queue.Empty:
                         continue
         except KeyboardInterrupt:
             for test in runtests:
                 test.abort()
 
         channels = []
 
         return result
 
 # Save the most recent 5 wall-clock runtimes of each test to a
 # human-readable text file named .testtimes. Tests are sorted
 # alphabetically, while times for each test are listed from oldest to
 # newest.
 
 def loadtimes(outputdir):
     times = []
     try:
         with open(os.path.join(outputdir, b'.testtimes-')) as fp:
             for line in fp:
                 ts = line.split()
                 times.append((ts[0], [float(t) for t in ts[1:]]))
     except IOError as err:
         if err.errno != errno.ENOENT:
             raise
     return times
 
 def savetimes(outputdir, result):
     saved = dict(loadtimes(outputdir))
     maxruns = 5
     skipped = set([str(t[0]) for t in result.skipped])
     for tdata in result.times:
         test, real = tdata[0], tdata[3]
         if test not in skipped:
             ts = saved.setdefault(test, [])
             ts.append(real)
             ts[:] = ts[-maxruns:]
 
     fd, tmpname = tempfile.mkstemp(prefix=b'.testtimes',
                                    dir=outputdir, text=True)
     with os.fdopen(fd, 'w') as fp:
         for name, ts in sorted(saved.items()):
             fp.write('%s %s\n' % (name, ' '.join(['%.3f' % (t,) for t in ts])))
     timepath = os.path.join(outputdir, b'.testtimes')
     try:
         os.unlink(timepath)
     except OSError:
         pass
     try:
         os.rename(tmpname, timepath)
     except OSError:
         pass
 
 class TextTestRunner(unittest.TextTestRunner):
     """Custom unittest test runner that uses appropriate settings."""
 
     def __init__(self, runner, *args, **kwargs):
         super(TextTestRunner, self).__init__(*args, **kwargs)
 
         self._runner = runner
 
     def listtests(self, test):
         result = TestResult(self._runner.options, self.stream,
                             self.descriptions, 0)
         test = sorted(test, key=lambda t: t.name)
         for t in test:
             print(t.name)
             result.addSuccess(t)
 
         if self._runner.options.xunit:
             with open(self._runner.options.xunit, "wb") as xuf:
                 self._writexunit(result, xuf)
 
         if self._runner.options.json:
             jsonpath = os.path.join(self._runner._outputdir, b'report.json')
             with open(jsonpath, 'w') as fp:
                 self._writejson(result, fp)
 
         return result
 
     def run(self, test):
         result = TestResult(self._runner.options, self.stream,
                             self.descriptions, self.verbosity)
 
         test(result)
 
         failed = len(result.failures)
         skipped = len(result.skipped)
         ignored = len(result.ignored)
 
         with iolock:
             self.stream.writeln('')
 
             if not self._runner.options.noskips:
                 for test, msg in result.skipped:
                     formatted = 'Skipped %s: %s\n' % (test.name, msg)
                     self.stream.write(highlightmsg(formatted, result.color))
             for test, msg in result.failures:
                 formatted = 'Failed %s: %s\n' % (test.name, msg)
                 self.stream.write(highlightmsg(formatted, result.color))
             for test, msg in result.errors:
                 self.stream.writeln('Errored %s: %s' % (test.name, msg))
 
             if self._runner.options.xunit:
                 with open(self._runner.options.xunit, "wb") as xuf:
                     self._writexunit(result, xuf)
 
             if self._runner.options.json:
                 jsonpath = os.path.join(self._runner._outputdir, b'report.json')
                 with open(jsonpath, 'w') as fp:
                     self._writejson(result, fp)
 
             self._runner._checkhglib('Tested')
 
             savetimes(self._runner._outputdir, result)
 
             if failed and self._runner.options.known_good_rev:
                 self._bisecttests(t for t, m in result.failures)
             self.stream.writeln(
                 '# Ran %d tests, %d skipped, %d failed.'
                 % (result.testsRun, skipped + ignored, failed))
             if failed:
                 self.stream.writeln('python hash seed: %s' %
                     os.environ['PYTHONHASHSEED'])
             if self._runner.options.time:
                 self.printtimes(result.times)
+
+            if self._runner.options.exceptions:
+                exceptions = aggregateexceptions(
+                    os.path.join(self._runner._outputdir, b'exceptions'))
+                total = sum(exceptions.values())
+
+                self.stream.writeln('Exceptions Report:')
+                self.stream.writeln('%d total from %d frames' %
+                                    (total, len(exceptions)))
+                for (frame, line, exc), count in exceptions.most_common():
+                    self.stream.writeln('%d\t%s: %s' % (count, frame, exc))
+
             self.stream.flush()
 
         return result
 
     def _bisecttests(self, tests):
         bisectcmd = ['hg', 'bisect']
         bisectrepo = self._runner.options.bisect_repo
         if bisectrepo:
             bisectcmd.extend(['-R', os.path.abspath(bisectrepo)])
         def pread(args):
             env = os.environ.copy()
             env['HGPLAIN'] = '1'
             p = subprocess.Popen(args, stderr=subprocess.STDOUT,
                                  stdout=subprocess.PIPE, env=env)
             data = p.stdout.read()
             p.wait()
             return data
         for test in tests:
             pread(bisectcmd + ['--reset']),
             pread(bisectcmd + ['--bad', '.'])
             pread(bisectcmd + ['--good', self._runner.options.known_good_rev])
             # TODO: we probably need to forward more options
             # that alter hg's behavior inside the tests.
             opts = ''
             withhg = self._runner.options.with_hg
             if withhg:
                 opts += ' --with-hg=%s ' % shellquote(_strpath(withhg))
             rtc = '%s %s %s %s' % (sys.executable, sys.argv[0], opts,
                                    test)
             data = pread(bisectcmd + ['--command', rtc])
             m = re.search(
                 (br'\nThe first (?P<goodbad>bad|good) revision '
                  br'is:\nchangeset: +\d+:(?P<node>[a-f0-9]+)\n.*\n'
                  br'summary: +(?P<summary>[^\n]+)\n'),
                 data, (re.MULTILINE | re.DOTALL))
             if m is None:
                 self.stream.writeln(
                     'Failed to identify failure point for %s' % test)
                 continue
             dat = m.groupdict()
             verb = 'broken' if dat['goodbad'] == 'bad' else 'fixed'
             self.stream.writeln(
                 '%s %s by %s (%s)' % (
                     test, verb, dat['node'], dat['summary']))
 
     def printtimes(self, times):
         # iolock held by run
         self.stream.writeln('# Producing time report')
         times.sort(key=lambda t: (t[3]))
         cols = '%7.3f %7.3f %7.3f %7.3f %7.3f   %s'
         self.stream.writeln('%-7s %-7s %-7s %-7s %-7s   %s' %
                             ('start', 'end', 'cuser', 'csys', 'real', 'Test'))
         for tdata in times:
             test = tdata[0]
             cuser, csys, real, start, end = tdata[1:6]
             self.stream.writeln(cols % (start, end, cuser, csys, real, test))
 
     @staticmethod
     def _writexunit(result, outf):
         # See http://llg.cubic.org/docs/junit/ for a reference.
         timesd = dict((t[0], t[3]) for t in result.times)
         doc = minidom.Document()
         s = doc.createElement('testsuite')
         s.setAttribute('name', 'run-tests')
         s.setAttribute('tests', str(result.testsRun))
         s.setAttribute('errors', "0") # TODO
         s.setAttribute('failures', str(len(result.failures)))
         s.setAttribute('skipped', str(len(result.skipped) +
                                       len(result.ignored)))
         doc.appendChild(s)
         for tc in result.successes:
             t = doc.createElement('testcase')
             t.setAttribute('name', tc.name)
             tctime = timesd.get(tc.name)
             if tctime is not None:
                 t.setAttribute('time', '%.3f' % tctime)
             s.appendChild(t)
         for tc, err in sorted(result.faildata.items()):
             t = doc.createElement('testcase')
             t.setAttribute('name', tc)
             tctime = timesd.get(tc)
             if tctime is not None:
                 t.setAttribute('time', '%.3f' % tctime)
             # createCDATASection expects a unicode or it will
             # convert using default conversion rules, which will
             # fail if string isn't ASCII.
             err = cdatasafe(err).decode('utf-8', 'replace')
             cd = doc.createCDATASection(err)
             # Use 'failure' here instead of 'error' to match errors = 0,
             # failures = len(result.failures) in the testsuite element.
             failelem = doc.createElement('failure')
             failelem.setAttribute('message', 'output changed')
             failelem.setAttribute('type', 'output-mismatch')
             failelem.appendChild(cd)
             t.appendChild(failelem)
             s.appendChild(t)
         for tc, message in result.skipped:
             # According to the schema, 'skipped' has no attributes. So store
             # the skip message as a text node instead.
             t = doc.createElement('testcase')
             t.setAttribute('name', tc.name)
             binmessage = message.encode('utf-8')
             message = cdatasafe(binmessage).decode('utf-8', 'replace')
             cd = doc.createCDATASection(message)
             skipelem = doc.createElement('skipped')
             skipelem.appendChild(cd)
             t.appendChild(skipelem)
             s.appendChild(t)
         outf.write(doc.toprettyxml(indent='  ', encoding='utf-8'))
 
     @staticmethod
     def _writejson(result, outf):
         timesd = {}
         for tdata in result.times:
             test = tdata[0]
             timesd[test] = tdata[1:]
 
         outcome = {}
         groups = [('success', ((tc, None)
                    for tc in result.successes)),
                   ('failure', result.failures),
                   ('skip', result.skipped)]
         for res, testcases in groups:
             for tc, __ in testcases:
                 if tc.name in timesd:
                     diff = result.faildata.get(tc.name, b'')
                     try:
                         diff = diff.decode('unicode_escape')
                     except UnicodeDecodeError as e:
                         diff = '%r decoding diff, sorry' % e
                     tres = {'result': res,
                             'time': ('%0.3f' % timesd[tc.name][2]),
                             'cuser': ('%0.3f' % timesd[tc.name][0]),
                             'csys': ('%0.3f' % timesd[tc.name][1]),
                             'start': ('%0.3f' % timesd[tc.name][3]),
                             'end': ('%0.3f' % timesd[tc.name][4]),
                             'diff': diff,
                             }
                 else:
                     # blacklisted test
                     tres = {'result': res}
 
                 outcome[tc.name] = tres
         jsonout = json.dumps(outcome, sort_keys=True, indent=4,
                              separators=(',', ': '))
         outf.writelines(("testreport =", jsonout))
 
 class TestRunner(object):
     """Holds context for executing tests.
 
     Tests rely on a lot of state. This object holds it for them.
     """
 
     # Programs required to run tests.
     REQUIREDTOOLS = [
         b'diff',
         b'grep',
         b'unzip',
         b'gunzip',
         b'bunzip2',
         b'sed',
     ]
 
     # Maps file extensions to test class.
     TESTTYPES = [
         (b'.py', PythonTest),
         (b'.t', TTest),
     ]
 
     def __init__(self):
         self.options = None
         self._hgroot = None
         self._testdir = None
         self._outputdir = None
         self._hgtmp = None
         self._installdir = None
         self._bindir = None
         self._tmpbinddir = None
         self._pythondir = None
         self._coveragefile = None
         self._createdfiles = []
         self._hgcommand = None
         self._hgpath = None
         self._portoffset = 0
         self._ports = {}
 
     def run(self, args, parser=None):
         """Run the test suite."""
         oldmask = os.umask(0o22)
         try:
             parser = parser or getparser()
             options = parseargs(args, parser)
             tests = [_bytespath(a) for a in options.tests]
             if options.test_list is not None:
                 for listfile in options.test_list:
                     with open(listfile, 'rb') as f:
                         tests.extend(t for t in f.read().splitlines() if t)
             self.options = options
 
             self._checktools()
             testdescs = self.findtests(tests)
             if options.profile_runner:
                 import statprof
                 statprof.start()
             result = self._run(testdescs)
             if options.profile_runner:
                 statprof.stop()
                 statprof.display()
             return result
 
         finally:
             os.umask(oldmask)
 
     def _run(self, testdescs):
         if self.options.random:
             random.shuffle(testdescs)
         else:
             # keywords for slow tests
             slow = {b'svn': 10,
                     b'cvs': 10,
                     b'hghave': 10,
                     b'largefiles-update': 10,
                     b'run-tests': 10,
                     b'corruption': 10,
                     b'race': 10,
                     b'i18n': 10,
                     b'check': 100,
                     b'gendoc': 100,
                     b'contrib-perf': 200,
                    }
             perf = {}
             def sortkey(f):
                 # run largest tests first, as they tend to take the longest
                 f = f['path']
                 try:
                     return perf[f]
                 except KeyError:
                     try:
                         val = -os.stat(f).st_size
                     except OSError as e:
                         if e.errno != errno.ENOENT:
                             raise
                         perf[f] = -1e9 # file does not exist, tell early
                         return -1e9
                     for kw, mul in slow.items():
                         if kw in f:
                             val *= mul
                     if f.endswith(b'.py'):
                         val /= 10.0
                     perf[f] = val / 1000.0
                     return perf[f]
             testdescs.sort(key=sortkey)
 
         self._testdir = osenvironb[b'TESTDIR'] = getattr(
             os, 'getcwdb', os.getcwd)()
         # assume all tests in same folder for now
         if testdescs:
             pathname = os.path.dirname(testdescs[0]['path'])
             if pathname:
                 osenvironb[b'TESTDIR'] = os.path.join(osenvironb[b'TESTDIR'],
                                                       pathname)
         if self.options.outputdir:
             self._outputdir = canonpath(_bytespath(self.options.outputdir))
         else:
             self._outputdir = self._testdir
             if testdescs and pathname:
                 self._outputdir = os.path.join(self._outputdir, pathname)
 
         if 'PYTHONHASHSEED' not in os.environ:
             # use a random python hash seed all the time
             # we do the randomness ourself to know what seed is used
             os.environ['PYTHONHASHSEED'] = str(random.getrandbits(32))
 
         if self.options.tmpdir:
             self.options.keep_tmpdir = True
             tmpdir = _bytespath(self.options.tmpdir)
             if os.path.exists(tmpdir):
                 # Meaning of tmpdir has changed since 1.3: we used to create
                 # HGTMP inside tmpdir; now HGTMP is tmpdir.  So fail if
                 # tmpdir already exists.
                 print("error: temp dir %r already exists" % tmpdir)
                 return 1
 
                 # Automatically removing tmpdir sounds convenient, but could
                 # really annoy anyone in the habit of using "--tmpdir=/tmp"
                 # or "--tmpdir=$HOME".
                 #vlog("# Removing temp dir", tmpdir)
                 #shutil.rmtree(tmpdir)
             os.makedirs(tmpdir)
         else:
             d = None
             if os.name == 'nt':
                 # without this, we get the default temp dir location, but
                 # in all lowercase, which causes troubles with paths (issue3490)
                 d = osenvironb.get(b'TMP', None)
             tmpdir = tempfile.mkdtemp(b'', b'hgtests.', d)
 
         self._hgtmp = osenvironb[b'HGTMP'] = (
             os.path.realpath(tmpdir))
 
         if self.options.with_hg:
             self._installdir = None
             whg = self.options.with_hg
             self._bindir = os.path.dirname(os.path.realpath(whg))
             assert isinstance(self._bindir, bytes)
             self._hgcommand = os.path.basename(whg)
             self._tmpbindir = os.path.join(self._hgtmp, b'install', b'bin')
             os.makedirs(self._tmpbindir)
 
             # This looks redundant with how Python initializes sys.path from
             # the location of the script being executed.  Needed because the
             # "hg" specified by --with-hg is not the only Python script
             # executed in the test suite that needs to import 'mercurial'
             # ... which means it's not really redundant at all.
             self._pythondir = self._bindir
         else:
             self._installdir = os.path.join(self._hgtmp, b"install")
             self._bindir = os.path.join(self._installdir, b"bin")
             self._hgcommand = b'hg'
             self._tmpbindir = self._bindir
             self._pythondir = os.path.join(self._installdir, b"lib", b"python")
 
         # set CHGHG, then replace "hg" command by "chg"
         chgbindir = self._bindir
         if self.options.chg or self.options.with_chg:
             osenvironb[b'CHGHG'] = os.path.join(self._bindir, self._hgcommand)
         else:
             osenvironb.pop(b'CHGHG', None)  # drop flag for hghave
         if self.options.chg:
             self._hgcommand = b'chg'
         elif self.options.with_chg:
             chgbindir = os.path.dirname(os.path.realpath(self.options.with_chg))
             self._hgcommand = os.path.basename(self.options.with_chg)
 
         osenvironb[b"BINDIR"] = self._bindir
         osenvironb[b"PYTHON"] = PYTHON
 
         if self.options.with_python3:
             osenvironb[b'PYTHON3'] = self.options.with_python3
 
         fileb = _bytespath(__file__)
         runtestdir = os.path.abspath(os.path.dirname(fileb))
         osenvironb[b'RUNTESTDIR'] = runtestdir
         if PYTHON3:
             sepb = _bytespath(os.pathsep)
         else:
             sepb = os.pathsep
         path = [self._bindir, runtestdir] + osenvironb[b"PATH"].split(sepb)
         if os.path.islink(__file__):
             # test helper will likely be at the end of the symlink
             realfile = os.path.realpath(fileb)
             realdir = os.path.abspath(os.path.dirname(realfile))
             path.insert(2, realdir)
         if chgbindir != self._bindir:
             path.insert(1, chgbindir)
         if self._testdir != runtestdir:
             path = [self._testdir] + path
         if self._tmpbindir != self._bindir:
             path = [self._tmpbindir] + path
         osenvironb[b"PATH"] = sepb.join(path)
 
         # Include TESTDIR in PYTHONPATH so that out-of-tree extensions
         # can run .../tests/run-tests.py test-foo where test-foo
         # adds an extension to HGRC. Also include run-test.py directory to
         # import modules like heredoctest.
         pypath = [self._pythondir, self._testdir, runtestdir]
         # We have to augment PYTHONPATH, rather than simply replacing
         # it, in case external libraries are only available via current
         # PYTHONPATH.  (In particular, the Subversion bindings on OS X
         # are in /opt/subversion.)
         oldpypath = osenvironb.get(IMPL_PATH)
         if oldpypath:
             pypath.append(oldpypath)
         osenvironb[IMPL_PATH] = sepb.join(pypath)
 
         if self.options.pure:
             os.environ["HGTEST_RUN_TESTS_PURE"] = "--pure"
             os.environ["HGMODULEPOLICY"] = "py"
 
         if self.options.allow_slow_tests:
             os.environ["HGTEST_SLOW"] = "slow"
         elif 'HGTEST_SLOW' in os.environ:
             del os.environ['HGTEST_SLOW']
 
         self._coveragefile = os.path.join(self._testdir, b'.coverage')
 
+        if self.options.exceptions:
+            exceptionsdir = os.path.join(self._outputdir, b'exceptions')
+            try:
+                os.makedirs(exceptionsdir)
+            except OSError as e:
+                if e.errno != errno.EEXIST:
+                    raise
+
+            # Remove all existing exception reports.
+            for f in os.listdir(exceptionsdir):
+                os.unlink(os.path.join(exceptionsdir, f))
+
+            osenvironb[b'HGEXCEPTIONSDIR'] = exceptionsdir
+            logexceptions = os.path.join(self._testdir, b'logexceptions.py')
+            self.options.extra_config_opt.append(
+                'extensions.logexceptions=%s' % logexceptions.decode('utf-8'))
+
         vlog("# Using TESTDIR", self._testdir)
         vlog("# Using RUNTESTDIR", osenvironb[b'RUNTESTDIR'])
         vlog("# Using HGTMP", self._hgtmp)
         vlog("# Using PATH", os.environ["PATH"])
         vlog("# Using", IMPL_PATH, osenvironb[IMPL_PATH])
         vlog("# Writing to directory", self._outputdir)
 
         try:
             return self._runtests(testdescs) or 0
         finally:
             time.sleep(.1)
             self._cleanup()
 
     def findtests(self, args):
         """Finds possible test files from arguments.
 
         If you wish to inject custom tests into the test harness, this would
         be a good function to monkeypatch or override in a derived class.
         """
         if not args:
             if self.options.changed:
                 proc = Popen4('hg st --rev "%s" -man0 .' %
                               self.options.changed, None, 0)
                 stdout, stderr = proc.communicate()
                 args = stdout.strip(b'\0').split(b'\0')
             else:
                 args = os.listdir(b'.')
 
         expanded_args = []
         for arg in args:
             if os.path.isdir(arg):
                 if not arg.endswith(b'/'):
                     arg += b'/'
                 expanded_args.extend([arg + a for a in os.listdir(arg)])
             else:
                 expanded_args.append(arg)
         args = expanded_args
 
         tests = []
         for t in args:
             if not (os.path.basename(t).startswith(b'test-')
                     and (t.endswith(b'.py') or t.endswith(b'.t'))):
                 continue
             if t.endswith(b'.t'):
                 # .t file may contain multiple test cases
                 cases = sorted(parsettestcases(t))
                 if cases:
                     tests += [{'path': t, 'case': c} for c in sorted(cases)]
                 else:
                     tests.append({'path': t})
             else:
                 tests.append({'path': t})
         return tests
 
     def _runtests(self, testdescs):
         def _reloadtest(test, i):
             # convert a test back to its description dict
             desc = {'path': test.path}
             case = getattr(test, '_case', None)
             if case:
                 desc['case'] = case
             return self._gettest(desc, i)
 
         try:
             if self.options.restart:
                 orig = list(testdescs)
                 while testdescs:
                     desc = testdescs[0]
                     # desc['path'] is a relative path
                     if 'case' in desc:
                         errpath = b'%s.%s.err' % (desc['path'], desc['case'])
                     else:
                         errpath = b'%s.err' % desc['path']
                     errpath = os.path.join(self._outputdir, errpath)
                     if os.path.exists(errpath):
                         break
                     testdescs.pop(0)
                 if not testdescs:
                     print("running all tests")
                     testdescs = orig
 
             tests = [self._gettest(d, i) for i, d in enumerate(testdescs)]
 
             failed = False
             kws = self.options.keywords
             if kws is not None and PYTHON3:
                 kws = kws.encode('utf-8')
 
             suite = TestSuite(self._testdir,
                               jobs=self.options.jobs,
                               whitelist=self.options.whitelisted,
                               blacklist=self.options.blacklist,
                               retest=self.options.retest,
                               keywords=kws,
                               loop=self.options.loop,
                               runs_per_test=self.options.runs_per_test,
                               showchannels=self.options.showchannels,
                               tests=tests, loadtest=_reloadtest)
             verbosity = 1
             if self.options.verbose:
                 verbosity = 2
             runner = TextTestRunner(self, verbosity=verbosity)
 
             if self.options.list_tests:
                 result = runner.listtests(suite)
             else:
                 if self._installdir:
                     self._installhg()
                     self._checkhglib("Testing")
                 else:
                     self._usecorrectpython()
                 if self.options.chg:
                     assert self._installdir
                     self._installchg()
 
                 result = runner.run(suite)
 
             if result.failures:
                 failed = True
 
             if self.options.anycoverage:
                 self._outputcoverage()
         except KeyboardInterrupt:
             failed = True
             print("\ninterrupted!")
 
         if failed:
             return 1
 
     def _getport(self, count):
         port = self._ports.get(count) # do we have a cached entry?
         if port is None:
             portneeded = 3
             # above 100 tries we just give up and let test reports failure
             for tries in xrange(100):
                 allfree = True
                 port = self.options.port + self._portoffset
                 for idx in xrange(portneeded):
                     if not checkportisavailable(port + idx):
                         allfree = False
                         break
                 self._portoffset += portneeded
                 if allfree:
                     break
             self._ports[count] = port
         return port
 
     def _gettest(self, testdesc, count):
         """Obtain a Test by looking at its filename.
 
         Returns a Test instance. The Test may not be runnable if it doesn't
         map to a known type.
         """
         path = testdesc['path']
         lctest = path.lower()
         testcls = Test
 
         for ext, cls in self.TESTTYPES:
             if lctest.endswith(ext):
                 testcls = cls
                 break
 
         refpath = os.path.join(self._testdir, path)
         tmpdir = os.path.join(self._hgtmp, b'child%d' % count)
 
         # extra keyword parameters. 'case' is used by .t tests
         kwds = dict((k, testdesc[k]) for k in ['case'] if k in testdesc)
 
         t = testcls(refpath, self._outputdir, tmpdir,
                     keeptmpdir=self.options.keep_tmpdir,
                     debug=self.options.debug,
                     timeout=self.options.timeout,
                     startport=self._getport(count),
                     extraconfigopts=self.options.extra_config_opt,
                     py3kwarnings=self.options.py3k_warnings,
                     shell=self.options.shell,
                     hgcommand=self._hgcommand,
                     usechg=bool(self.options.with_chg or self.options.chg),
                     useipv6=useipv6, **kwds)
         t.should_reload = True
         return t
 
     def _cleanup(self):
         """Clean up state from this test invocation."""
         if self.options.keep_tmpdir:
             return
 
         vlog("# Cleaning up HGTMP", self._hgtmp)
         shutil.rmtree(self._hgtmp, True)
         for f in self._createdfiles:
             try:
                 os.remove(f)
             except OSError:
                 pass
 
     def _usecorrectpython(self):
         """Configure the environment to use the appropriate Python in tests."""
         # Tests must use the same interpreter as us or bad things will happen.
         pyexename = sys.platform == 'win32' and b'python.exe' or b'python'
         if getattr(os, 'symlink', None):
             vlog("# Making python executable in test path a symlink to '%s'" %
                  sys.executable)
             mypython = os.path.join(self._tmpbindir, pyexename)
             try:
                 if os.readlink(mypython) == sys.executable:
                     return
                 os.unlink(mypython)
             except OSError as err:
                 if err.errno != errno.ENOENT:
                     raise
             if self._findprogram(pyexename) != sys.executable:
                 try:
                     os.symlink(sys.executable, mypython)
                     self._createdfiles.append(mypython)
                 except OSError as err:
                     # child processes may race, which is harmless
                     if err.errno != errno.EEXIST:
                         raise
         else:
             exedir, exename = os.path.split(sys.executable)
             vlog("# Modifying search path to find %s as %s in '%s'" %
                  (exename, pyexename, exedir))
             path = os.environ['PATH'].split(os.pathsep)
             while exedir in path:
                 path.remove(exedir)
             os.environ['PATH'] = os.pathsep.join([exedir] + path)
             if not self._findprogram(pyexename):
                 print("WARNING: Cannot find %s in search path" % pyexename)
 
     def _installhg(self):
         """Install hg into the test environment.
 
         This will also configure hg with the appropriate testing settings.
         """
         vlog("# Performing temporary installation of HG")
         installerrs = os.path.join(self._hgtmp, b"install.err")
         compiler = ''
         if self.options.compiler:
             compiler = '--compiler ' + self.options.compiler
         if self.options.pure:
             pure = b"--pure"
         else:
             pure = b""
 
         # Run installer in hg root
         script = os.path.realpath(sys.argv[0])
         exe = sys.executable
         if PYTHON3:
             compiler = _bytespath(compiler)
             script = _bytespath(script)
             exe = _bytespath(exe)
         hgroot = os.path.dirname(os.path.dirname(script))
         self._hgroot = hgroot
         os.chdir(hgroot)
         nohome = b'--home=""'
         if os.name == 'nt':
             # The --home="" trick works only on OS where os.sep == '/'
             # because of a distutils convert_path() fast-path. Avoid it at
             # least on Windows for now, deal with .pydistutils.cfg bugs
             # when they happen.
             nohome = b''
         cmd = (b'%(exe)s setup.py %(pure)s clean --all'
                b' build %(compiler)s --build-base="%(base)s"'
                b' install --force --prefix="%(prefix)s"'
                b' --install-lib="%(libdir)s"'
                b' --install-scripts="%(bindir)s" %(nohome)s >%(logfile)s 2>&1'
                % {b'exe': exe, b'pure': pure,
                   b'compiler': compiler,
                   b'base': os.path.join(self._hgtmp, b"build"),
                   b'prefix': self._installdir, b'libdir': self._pythondir,
                   b'bindir': self._bindir,
                   b'nohome': nohome, b'logfile': installerrs})
 
         # setuptools requires install directories to exist.
         def makedirs(p):
             try:
                 os.makedirs(p)
             except OSError as e:
                 if e.errno != errno.EEXIST:
                     raise
         makedirs(self._pythondir)
         makedirs(self._bindir)
 
         vlog("# Running", cmd)
         if os.system(cmd) == 0:
             if not self.options.verbose:
                 try:
                     os.remove(installerrs)
                 except OSError as e:
                     if e.errno != errno.ENOENT:
                         raise
         else:
             f = open(installerrs, 'rb')
             for line in f:
                 if PYTHON3:
                     sys.stdout.buffer.write(line)
                 else:
                     sys.stdout.write(line)
             f.close()
             sys.exit(1)
         os.chdir(self._testdir)
 
         self._usecorrectpython()
 
         if self.options.py3k_warnings and not self.options.anycoverage:
             vlog("# Updating hg command to enable Py3k Warnings switch")
             f = open(os.path.join(self._bindir, 'hg'), 'rb')
             lines = [line.rstrip() for line in f]
             lines[0] += ' -3'
             f.close()
             f = open(os.path.join(self._bindir, 'hg'), 'wb')
             for line in lines:
                 f.write(line + '\n')
             f.close()
 
         hgbat = os.path.join(self._bindir, b'hg.bat')
         if os.path.isfile(hgbat):
             # hg.bat expects to be put in bin/scripts while run-tests.py
             # installation layout put it in bin/ directly. Fix it
             f = open(hgbat, 'rb')
             data = f.read()
             f.close()
             if b'"%~dp0..\python" "%~dp0hg" %*' in data:
                 data = data.replace(b'"%~dp0..\python" "%~dp0hg" %*',
                                     b'"%~dp0python" "%~dp0hg" %*')
                 f = open(hgbat, 'wb')
                 f.write(data)
                 f.close()
             else:
                 print('WARNING: cannot fix hg.bat reference to python.exe')
 
         if self.options.anycoverage:
             custom = os.path.join(self._testdir, 'sitecustomize.py')
             target = os.path.join(self._pythondir, 'sitecustomize.py')
             vlog('# Installing coverage trigger to %s' % target)
             shutil.copyfile(custom, target)
             rc = os.path.join(self._testdir, '.coveragerc')
             vlog('# Installing coverage rc to %s' % rc)
             os.environ['COVERAGE_PROCESS_START'] = rc
             covdir = os.path.join(self._installdir, '..', 'coverage')
             try:
                 os.mkdir(covdir)
             except OSError as e:
                 if e.errno != errno.EEXIST:
                     raise
 
             os.environ['COVERAGE_DIR'] = covdir
 
     def _checkhglib(self, verb):
         """Ensure that the 'mercurial' package imported by python is
         the one we expect it to be.  If not, print a warning to stderr."""
         if ((self._bindir == self._pythondir) and
             (self._bindir != self._tmpbindir)):
             # The pythondir has been inferred from --with-hg flag.
             # We cannot expect anything sensible here.
             return
         expecthg = os.path.join(self._pythondir, b'mercurial')
         actualhg = self._gethgpath()
         if os.path.abspath(actualhg) != os.path.abspath(expecthg):
             sys.stderr.write('warning: %s with unexpected mercurial lib: %s\n'
                              '         (expected %s)\n'
                              % (verb, actualhg, expecthg))
     def _gethgpath(self):
         """Return the path to the mercurial package that is actually found by
         the current Python interpreter."""
         if self._hgpath is not None:
             return self._hgpath
 
         cmd = b'%s -c "import mercurial; print (mercurial.__path__[0])"'
         cmd = cmd % PYTHON
         if PYTHON3:
             cmd = _strpath(cmd)
         pipe = os.popen(cmd)
         try:
             self._hgpath = _bytespath(pipe.read().strip())
         finally:
             pipe.close()
 
         return self._hgpath
 
     def _installchg(self):
         """Install chg into the test environment"""
         vlog('# Performing temporary installation of CHG')
         assert os.path.dirname(self._bindir) == self._installdir
         assert self._hgroot, 'must be called after _installhg()'
         cmd = (b'"%(make)s" clean install PREFIX="%(prefix)s"'
                % {b'make': 'make',  # TODO: switch by option or environment?
                   b'prefix': self._installdir})
         cwd = os.path.join(self._hgroot, b'contrib', b'chg')
         vlog("# Running", cmd)
         proc = subprocess.Popen(cmd, shell=True, cwd=cwd,
                                 stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT)
         out, _err = proc.communicate()
         if proc.returncode != 0:
             if PYTHON3:
                 sys.stdout.buffer.write(out)
             else:
                 sys.stdout.write(out)
             sys.exit(1)
 
     def _outputcoverage(self):
         """Produce code coverage output."""
         import coverage
         coverage = coverage.coverage
 
         vlog('# Producing coverage report')
         # chdir is the easiest way to get short, relative paths in the
         # output.
         os.chdir(self._hgroot)
         covdir = os.path.join(self._installdir, '..', 'coverage')
         cov = coverage(data_file=os.path.join(covdir, 'cov'))
 
         # Map install directory paths back to source directory.
         cov.config.paths['srcdir'] = ['.', self._pythondir]
 
         cov.combine()
 
         omit = [os.path.join(x, '*') for x in [self._bindir, self._testdir]]
         cov.report(ignore_errors=True, omit=omit)
 
         if self.options.htmlcov:
             htmldir = os.path.join(self._outputdir, 'htmlcov')
             cov.html_report(directory=htmldir, omit=omit)
         if self.options.annotate:
             adir = os.path.join(self._outputdir, 'annotated')
             if not os.path.isdir(adir):
                 os.mkdir(adir)
             cov.annotate(directory=adir, omit=omit)
 
     def _findprogram(self, program):
         """Search PATH for a executable program"""
         dpb = _bytespath(os.defpath)
         sepb = _bytespath(os.pathsep)
         for p in osenvironb.get(b'PATH', dpb).split(sepb):
             name = os.path.join(p, program)
             if os.name == 'nt' or os.access(name, os.X_OK):
                 return name
         return None
 
     def _checktools(self):
         """Ensure tools required to run tests are present."""
         for p in self.REQUIREDTOOLS:
             if os.name == 'nt' and not p.endswith('.exe'):
                 p += '.exe'
             found = self._findprogram(p)
             if found:
                 vlog("# Found prerequisite", p, "at", found)
             else:
                 print("WARNING: Did not find prerequisite tool: %s " %
                       p.decode("utf-8"))
 
+def aggregateexceptions(path):
+    exceptions = collections.Counter()
+
+    for f in os.listdir(path):
+        with open(os.path.join(path, f), 'rb') as fh:
+            data = fh.read().split(b'\0')
+            if len(data) != 4:
+                continue
+
+            exc, mainframe, hgframe, hgline = data
+            exc = exc.decode('utf-8')
+            mainframe = mainframe.decode('utf-8')
+            hgframe = hgframe.decode('utf-8')
+            hgline = hgline.decode('utf-8')
+            exceptions[(hgframe, hgline, exc)] += 1
+
+    return exceptions
+
 if __name__ == '__main__':
     runner = TestRunner()
 
     try:
         import msvcrt
         msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
         msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
         msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
     except ImportError:
         pass
 
     sys.exit(runner.run(sys.argv[1:]))