contrib: add a ratchet for tests in Python 3

This gives us an easy way to automatically update passing tests in Python 3.

contrib/python3-ratchet.py

@@ -0,0 +1,116 b''
+# Copyright 2012 Facebook
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+"""Find tests that newly pass under Python 3.
+
+The approach is simple: we maintain a whitelist of Python 3 passing
+tests in the repository, and periodically run all the /other/ tests
+and look for new passes. Any newly passing tests get automatically
+added to the whitelist.
+
+You probably want to run it like this:
+
+  $ cd tests
+  $ python3 ../contrib/python3-ratchet.py \
+  >   --working-tests=../contrib/python3-whitelist
+"""
+from __future__ import print_function
+from __future__ import absolute_import
+
+import argparse
+import json
+import os
+import subprocess
+import sys
+
+_hgenv = dict(os.environ)
+_hgenv.update({
+    'HGPLAIN': '1',
+    })
+
+_HG_FIRST_CHANGE = '9117c6561b0bd7792fa13b50d28239d51b78e51f'
+
+def _runhg(*args):
+    return subprocess.check_output(args, env=_hgenv)
+
+def _is_hg_repo(path):
+    return _runhg('hg', 'log', '-R', path,
+                  '-r0', '--template={node}').strip() == _HG_FIRST_CHANGE
+
+def _py3default():
+    if sys.version_info[0] >= 3:
+        return sys.executable
+    return 'python3'
+
+def main(argv=()):
+    p = argparse.ArgumentParser()
+    p.add_argument('--working-tests',
+                   help='List of tests that already work in Python 3.')
+    p.add_argument('--commit-to-repo',
+                   help='If set, commit newly fixed tests to the given repo')
+    p.add_argument('-j', default=os.sysconf(r'SC_NPROCESSORS_ONLN'), type=int,
+                   help='Number of parallel tests to run.')
+    p.add_argument('--python3', default=_py3default(),
+                   help='python3 interpreter to use for test run')
+    p.add_argument('--commit-user',
+                   default='[e-mail]',
+                   help='Username to specify when committing to a repo.')
+    opts = p.parse_args(argv)
+    if opts.commit_to_repo:
+        if not _is_hg_repo(opts.commit_to_repo):
+            print('abort: specified repository is not the hg repository')
+            sys.exit(1)
+    if not opts.working_tests or not os.path.isfile(opts.working_tests):
+        print('abort: --working-tests must exist and be a file (got %r)' %
+              opts.working_tests)
+        sys.exit(1)
+    elif opts.commit_to_repo:
+        root = _runhg('hg', 'root').strip()
+        if not opts.working_tests.startswith(root):
+            print('abort: if --commit-to-repo is given, '
+                  '--working-tests must be from that repo')
+            sys.exit(1)
+    try:
+        subprocess.check_call([opts.python3, '-c',
+                               'import sys ; '
+                               'assert ((3, 5) <= sys.version_info < (3, 6) '
+                               'or sys.version_info >= (3, 6, 2))'])
+    except subprocess.CalledProcessError:
+        print('warning: Python 3.6.0 and 3.6.1 have '
+              'a bug which breaks Mercurial')
+        print('(see https://bugs.python.org/issue29714 for details)')
+        # TODO(augie): uncomment exit when Python 3.6.2 is available
+        # sys.exit(1)
+
+    rt = subprocess.Popen([opts.python3, 'run-tests.py', '-j', str(opts.j),
+                           '--blacklist', opts.working_tests, '--json'])
+    rt.wait()
+    with open('report.json') as f:
+        data = f.read()
+    report = json.loads(data.split('=', 1)[1])
+    newpass = set()
+    for test, result in report.items():
+        if result['result'] != 'success':
+            continue
+        # A new passing test! Huzzah!
+        newpass.add(test)
+    if newpass:
+        # We already validated the repo, so we can just dive right in
+        # and commit.
+        if opts.commit_to_repo:
+            print(len(newpass), 'new passing tests on Python 3!')
+            with open(opts.working_tests) as f:
+                oldpass = {l for l in f.read().splitlines() if l}
+            with open(opts.working_tests, 'w') as f:
+                for p in sorted(oldpass | newpass):
+                    f.write('%s\n' % p)
+            _runhg('hg', 'commit', '-R', opts.commit_to_repo,
+                   '--user', opts.commit_user,
+                   '--message', 'python3: expand list of passing tests')
+        else:
+            print('Newly passing tests:', '\n'.join(sorted(newpass)))
+            sys.exit(2)
+
+if __name__ == '__main__':
+    main(sys.argv[1:])