Follow Fernando's suggestions.

IPython/core/page.py

@@ -1,332 +1,337 b''
 # encoding: utf-8
 """
 Paging capabilities for IPython.core
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 
 Notes
 -----
 
 For now this uses ipapi, so it can't be in IPython.utils.  If we can get
 rid of that dependency, we could move it there.
 -----
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import re
 import sys
 import tempfile
 
 from IPython.core import ipapi
 from IPython.core.error import TryNext
 from IPython.utils.cursesimport import use_curses
 from IPython.utils.data import chop
 from IPython.utils import io
 from IPython.utils.process import system
 from IPython.utils.terminal import get_terminal_size
 
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 esc_re = re.compile(r"(\x1b[^m]+m)")
 
 def page_dumb(strng, start=0, screen_lines=25):
     """Very dumb 'pager' in Python, for when nothing else works.
 
     Only moves forward, same interface as page(), except for pager_cmd and
     mode."""
 
     out_ln  = strng.splitlines()[start:]
     screens = chop(out_ln,screen_lines-1)
     if len(screens) == 1:
         print >>io.stdout, os.linesep.join(screens[0])
     else:
         last_escape = ""
         for scr in screens[0:-1]:
             hunk = os.linesep.join(scr)
             print >>io.stdout, last_escape + hunk
             if not page_more():
                 return
             esc_list = esc_re.findall(hunk)
             if len(esc_list) > 0:
                 last_escape = esc_list[-1]
         print >>io.stdout, last_escape + os.linesep.join(screens[-1])
 
 def _detect_screen_size(use_curses, screen_lines_def):
+    """Attempt to work out the number of lines on the screen.
+    
+    This is called by page(). It can raise an error (e.g. when run in the
+    test suite), so it's separated out so it can easily be called in a try block.
+    """
     if (TERM=='xterm' or TERM=='xterm-color') and sys.platform != 'sunos5':
         local_use_curses = use_curses
     else:
         # curses causes problems on many terminals other than xterm, and
         # some termios calls lock up on Sun OS5.
         local_use_curses = False
     if local_use_curses:
         import termios
         import curses
         # There is a bug in curses, where *sometimes* it fails to properly
         # initialize, and then after the endwin() call is made, the
         # terminal is left in an unusable state.  Rather than trying to
         # check everytime for this (by requesting and comparing termios
         # flags each time), we just save the initial terminal state and
         # unconditionally reset it every time.  It's cheaper than making
         # the checks.
         term_flags = termios.tcgetattr(sys.stdout)
 
         # Curses modifies the stdout buffer size by default, which messes
         # up Python's normal stdout buffering.  This would manifest itself
         # to IPython users as delayed printing on stdout after having used
         # the pager.
         #
         # We can prevent this by manually setting the NCURSES_NO_SETBUF
         # environment variable.  For more details, see:
         # http://bugs.python.org/issue10144
         NCURSES_NO_SETBUF = os.environ.get('NCURSES_NO_SETBUF', None)
         os.environ['NCURSES_NO_SETBUF'] = ''
         
         # Proceed with curses initialization
         scr = curses.initscr()
         screen_lines_real,screen_cols = scr.getmaxyx()
         curses.endwin()
 
         # Restore environment
         if NCURSES_NO_SETBUF is None:
             del os.environ['NCURSES_NO_SETBUF']
         else:
             os.environ['NCURSES_NO_SETBUF'] = NCURSES_NO_SETBUF
             
         # Restore terminal state in case endwin() didn't.
         termios.tcsetattr(sys.stdout,termios.TCSANOW,term_flags)
         # Now we have what we needed: the screen size in rows/columns
         return screen_lines_real
         #print '***Screen size:',screen_lines_real,'lines x',\
         #screen_cols,'columns.' # dbg
     else:
         return screen_lines_def
 
 def page(strng, start=0, screen_lines=0, pager_cmd=None):
     """Print a string, piping through a pager after a certain length.
 
     The screen_lines parameter specifies the number of *usable* lines of your
     terminal screen (total lines minus lines you need to reserve to show other
     information).
 
     If you set screen_lines to a number <=0, page() will try to auto-determine
     your screen size and will only use up to (screen_size+screen_lines) for
     printing, paging after that. That is, if you want auto-detection but need
     to reserve the bottom 3 lines of the screen, use screen_lines = -3, and for
     auto-detection without any lines reserved simply use screen_lines = 0.
 
     If a string won't fit in the allowed lines, it is sent through the
     specified pager command. If none given, look for PAGER in the environment,
     and ultimately default to less.
 
     If no system pager works, the string is sent through a 'dumb pager'
     written in python, very simplistic.
     """
 
     # Some routines may auto-compute start offsets incorrectly and pass a
     # negative value.  Offset to 0 for robustness.
     start = max(0, start)
 
     # first, try the hook
     ip = ipapi.get()
     if ip:
         try:
             ip.hooks.show_in_pager(strng)
             return
         except TryNext:
             pass
 
     # Ugly kludge, but calling curses.initscr() flat out crashes in emacs
     TERM = os.environ.get('TERM','dumb')
     if TERM in ['dumb','emacs'] and os.name != 'nt':
         print strng
         return
     # chop off the topmost part of the string we don't want to see
     str_lines = strng.splitlines()[start:]
     str_toprint = os.linesep.join(str_lines)
     num_newlines = len(str_lines)
     len_str = len(str_toprint)
 
     # Dumb heuristics to guesstimate number of on-screen lines the string
     # takes.  Very basic, but good enough for docstrings in reasonable
     # terminals. If someone later feels like refining it, it's not hard.
     numlines = max(num_newlines,int(len_str/80)+1)
 
     screen_lines_def = get_terminal_size()[1]
 
     # auto-determine screen size
     if screen_lines <= 0:
         try:
             screen_lines += _detect_screen_size(use_curses, screen_lines_def)
         except Exception:
             print >>io.stdout, str_toprint
             return
 
     #print 'numlines',numlines,'screenlines',screen_lines  # dbg
     if numlines <= screen_lines :
         #print '*** normal print'  # dbg
         print >>io.stdout, str_toprint
     else:
         # Try to open pager and default to internal one if that fails.
         # All failure modes are tagged as 'retval=1', to match the return
         # value of a failed system command.  If any intermediate attempt
         # sets retval to 1, at the end we resort to our own page_dumb() pager.
         pager_cmd = get_pager_cmd(pager_cmd)
         pager_cmd += ' ' + get_pager_start(pager_cmd,start)
         if os.name == 'nt':
             if pager_cmd.startswith('type'):
                 # The default WinXP 'type' command is failing on complex strings.
                 retval = 1
             else:
                 tmpname = tempfile.mktemp('.txt')
                 tmpfile = file(tmpname,'wt')
                 tmpfile.write(strng)
                 tmpfile.close()
                 cmd = "%s < %s" % (pager_cmd,tmpname)
                 if os.system(cmd):
                   retval = 1
                 else:
                   retval = None
                 os.remove(tmpname)
         else:
             try:
                 retval = None
                 # if I use popen4, things hang. No idea why.
                 #pager,shell_out = os.popen4(pager_cmd)
                 pager = os.popen(pager_cmd,'w')
                 pager.write(strng)
                 pager.close()
                 retval = pager.close()  # success returns None
             except IOError,msg:  # broken pipe when user quits
                 if msg.args == (32,'Broken pipe'):
                     retval = None
                 else:
                     retval = 1
             except OSError:
                 # Other strange problems, sometimes seen in Win2k/cygwin
                 retval = 1
         if retval is not None:
             page_dumb(strng,screen_lines=screen_lines)
 
 
 def page_file(fname, start=0, pager_cmd=None):
     """Page a file, using an optional pager command and starting line.
     """
 
     pager_cmd = get_pager_cmd(pager_cmd)
     pager_cmd += ' ' + get_pager_start(pager_cmd,start)
 
     try:
         if os.environ['TERM'] in ['emacs','dumb']:
             raise EnvironmentError
         system(pager_cmd + ' ' + fname)
     except:
         try:
             if start > 0:
                 start -= 1
             page(open(fname).read(),start)
         except:
             print 'Unable to show file',`fname`
 
 
 def get_pager_cmd(pager_cmd=None):
     """Return a pager command.
 
     Makes some attempts at finding an OS-correct one.
     """
     if os.name == 'posix':
         default_pager_cmd = 'less -r'  # -r for color control sequences
     elif os.name in ['nt','dos']:
         default_pager_cmd = 'type'
 
     if pager_cmd is None:
         try:
             pager_cmd = os.environ['PAGER']
         except:
             pager_cmd = default_pager_cmd
     return pager_cmd
 
 
 def get_pager_start(pager, start):
     """Return the string for paging files with an offset.
 
     This is the '+N' argument which less and more (under Unix) accept.
     """
 
     if pager in ['less','more']:
         if start:
             start_string = '+' + str(start)
         else:
             start_string = ''
     else:
         start_string = ''
     return start_string
 
 
 # (X)emacs on win32 doesn't like to be bypassed with msvcrt.getch()
 if os.name == 'nt' and os.environ.get('TERM','dumb') != 'emacs':
     import msvcrt
     def page_more():
         """ Smart pausing between pages
 
         @return:    True if need print more lines, False if quit
         """
         io.stdout.write('---Return to continue, q to quit--- ')
         ans = msvcrt.getch()
         if ans in ("q", "Q"):
             result = False
         else:
             result = True
         io.stdout.write("\b"*37 + " "*37 + "\b"*37)
         return result
 else:
     def page_more():
         ans = raw_input('---Return to continue, q to quit--- ')
         if ans.lower().startswith('q'):
             return False
         else:
             return True
 
 
 def snip_print(str,width = 75,print_full = 0,header = ''):
     """Print a string snipping the midsection to fit in width.
 
     print_full: mode control:
       - 0: only snip long strings
       - 1: send to page() directly.
       - 2: snip long strings and ask for full length viewing with page()
     Return 1 if snipping was necessary, 0 otherwise."""
 
     if print_full == 1:
         page(header+str)
         return 0
 
     print header,
     if len(str) < width:
         print str
         snip = 0
     else:
         whalf = int((width -5)/2)
         print str[:whalf] + ' <...> ' + str[-whalf:]
         snip = 1
     if snip and print_full == 2:
         if raw_input(header+' Snipped. View (y/n)? [N]').lower() == 'y':
             page(str)
     return snip
 

IPython/testing/tools.py

@@ -1,400 +1,402 b''
 """Generic testing tools that do NOT depend on Twisted.
 
 In particular, this module exposes a set of top-level assert* functions that
 can be used in place of nose.tools.assert* in method generators (the ones in
 nose can not, at least as of nose 0.10.4).
 
 Note: our testing package contains testing.util, which does depend on Twisted
 and provides utilities for tests that manage Deferreds.  All testing support
 tools that only depend on nose, IPython or the standard library should go here
 instead.
 
 
 Authors
 -------
 - Fernando Perez <[e-mail]>
 """
 
 from __future__ import absolute_import
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import re
 import sys
 import tempfile
 
 from contextlib import contextmanager
 from io import StringIO
 
 try:
     # These tools are used by parts of the runtime, so we make the nose
     # dependency optional at this point.  Nose is a hard dependency to run the
     # test suite, but NOT to use ipython itself.
     import nose.tools as nt
     has_nose = True
 except ImportError:
     has_nose = False
 
 from IPython.config.loader import Config
 from IPython.utils.process import find_cmd, getoutputerror
 from IPython.utils.text import list_strings, getdefaultencoding
 from IPython.utils.io import temp_pyfile, Tee
 from IPython.utils import py3compat
 
 from . import decorators as dec
 from . import skipdoctest
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 # Make a bunch of nose.tools assert wrappers that can be used in test
 # generators.  This will expose an assert* function for each one in nose.tools.
 
 _tpl = """
 def %(name)s(*a,**kw):
     return nt.%(name)s(*a,**kw)
 """
 
 if has_nose:
     for _x in [a for a in dir(nt) if a.startswith('assert')]:
         exec _tpl % dict(name=_x)
 
 #-----------------------------------------------------------------------------
 # Functions and classes
 #-----------------------------------------------------------------------------
 
 # The docstring for full_path doctests differently on win32 (different path
 # separator) so just skip the doctest there.  The example remains informative.
 doctest_deco = skipdoctest.skip_doctest if sys.platform == 'win32' else dec.null_deco
 
 @doctest_deco
 def full_path(startPath,files):
     """Make full paths for all the listed files, based on startPath.
 
     Only the base part of startPath is kept, since this routine is typically
     used with a script's __file__ variable as startPath.  The base of startPath
     is then prepended to all the listed files, forming the output list.
 
     Parameters
     ----------
       startPath : string
         Initial path to use as the base for the results.  This path is split
       using os.path.split() and only its first component is kept.
 
       files : string or list
         One or more files.
 
     Examples
     --------
 
     >>> full_path('/foo/bar.py',['a.txt','b.txt'])
     ['/foo/a.txt', '/foo/b.txt']
 
     >>> full_path('/foo',['a.txt','b.txt'])
     ['/a.txt', '/b.txt']
 
     If a single file is given, the output is still a list:
     >>> full_path('/foo','a.txt')
     ['/a.txt']
     """
 
     files = list_strings(files)
     base = os.path.split(startPath)[0]
     return [ os.path.join(base,f) for f in files ]
 
 
 def parse_test_output(txt):
     """Parse the output of a test run and return errors, failures.
 
     Parameters
     ----------
     txt : str
       Text output of a test run, assumed to contain a line of one of the
       following forms::
         'FAILED (errors=1)'
         'FAILED (failures=1)'
         'FAILED (errors=1, failures=1)'
 
     Returns
     -------
     nerr, nfail: number of errors and failures.
     """
 
     err_m = re.search(r'^FAILED \(errors=(\d+)\)', txt, re.MULTILINE)
     if err_m:
         nerr = int(err_m.group(1))
         nfail = 0
         return  nerr, nfail
 
     fail_m = re.search(r'^FAILED \(failures=(\d+)\)', txt, re.MULTILINE)
     if fail_m:
         nerr = 0
         nfail = int(fail_m.group(1))
         return  nerr, nfail
 
     both_m = re.search(r'^FAILED \(errors=(\d+), failures=(\d+)\)', txt,
                        re.MULTILINE)
     if both_m:
         nerr = int(both_m.group(1))
         nfail = int(both_m.group(2))
         return  nerr, nfail
 
     # If the input didn't match any of these forms, assume no error/failures
     return 0, 0
 
 
 # So nose doesn't think this is a test
 parse_test_output.__test__ = False
 
 
 def default_argv():
     """Return a valid default argv for creating testing instances of ipython"""
 
     return ['--quick', # so no config file is loaded
             # Other defaults to minimize side effects on stdout
             '--colors=NoColor', '--no-term-title','--no-banner',
             '--autocall=0']
 
 
 def default_config():
     """Return a config object with good defaults for testing."""
     config = Config()
     config.TerminalInteractiveShell.colors = 'NoColor'
     config.TerminalTerminalInteractiveShell.term_title = False,
     config.TerminalInteractiveShell.autocall = 0
     config.HistoryManager.hist_file = tempfile.mktemp(u'test_hist.sqlite')
     config.HistoryManager.db_cache_size = 10000
     return config
 
 
 def ipexec(fname, options=None):
     """Utility to call 'ipython filename'.
 
     Starts IPython witha minimal and safe configuration to make startup as fast
     as possible.
 
     Note that this starts IPython in a subprocess!
 
     Parameters
     ----------
     fname : str
       Name of file to be executed (should have .py or .ipy extension).
 
     options : optional, list
       Extra command-line flags to be passed to IPython.
 
     Returns
     -------
     (stdout, stderr) of ipython subprocess.
     """
     if options is None: options = []
 
     # For these subprocess calls, eliminate all prompt printing so we only see
     # output from script execution
     prompt_opts = [ '--InteractiveShell.prompt_in1=""',
                     '--InteractiveShell.prompt_in2=""',
                     '--InteractiveShell.prompt_out=""'
     ]
     cmdargs = ' '.join(default_argv() + prompt_opts + options)
 
     _ip = get_ipython()
     test_dir = os.path.dirname(__file__)
 
     ipython_cmd = find_cmd('ipython3' if py3compat.PY3 else 'ipython')
     # Absolute path for filename
     full_fname = os.path.join(test_dir, fname)
     full_cmd = '%s %s %s' % (ipython_cmd, cmdargs, full_fname)
     #print >> sys.stderr, 'FULL CMD:', full_cmd # dbg
     out = getoutputerror(full_cmd)
     # `import readline` causes 'ESC[?1034h' to be the first output sometimes,
     # so strip that off the front of the first line if it is found
     if out:
         first = out[0]
         m = re.match(r'\x1b\[[^h]+h', first)
         if m:
             # strip initial readline escape
             out = list(out)
             out[0] = first[len(m.group()):]
             out = tuple(out)
     return out
 
 
 def ipexec_validate(fname, expected_out, expected_err='',
                     options=None):
     """Utility to call 'ipython filename' and validate output/error.
 
     This function raises an AssertionError if the validation fails.
 
     Note that this starts IPython in a subprocess!
 
     Parameters
     ----------
     fname : str
       Name of the file to be executed (should have .py or .ipy extension).
 
     expected_out : str
       Expected stdout of the process.
 
     expected_err : optional, str
       Expected stderr of the process.
 
     options : optional, list
       Extra command-line flags to be passed to IPython.
 
     Returns
     -------
     None
     """
 
     import nose.tools as nt
 
     out, err = ipexec(fname)
     #print 'OUT', out  # dbg
     #print 'ERR', err  # dbg
     # If there are any errors, we must check those befor stdout, as they may be
     # more informative than simply having an empty stdout.
     if err:
         if expected_err:
             nt.assert_equals(err.strip(), expected_err.strip())
         else:
             raise ValueError('Running file %r produced error: %r' %
                              (fname, err))
     # If no errors or output on stderr was expected, match stdout
     nt.assert_equals(out.strip(), expected_out.strip())
 
 
 class TempFileMixin(object):
     """Utility class to create temporary Python/IPython files.
 
     Meant as a mixin class for test cases."""
 
     def mktmp(self, src, ext='.py'):
         """Make a valid python temp file."""
         fname, f = temp_pyfile(src, ext)
         self.tmpfile = f
         self.fname = fname
 
     def tearDown(self):
         if hasattr(self, 'tmpfile'):
             # If the tmpfile wasn't made because of skipped tests, like in
             # win32, there's nothing to cleanup.
             self.tmpfile.close()
             try:
                 os.unlink(self.fname)
             except:
                 # On Windows, even though we close the file, we still can't
                 # delete it.  I have no clue why
                 pass
 
 pair_fail_msg = ("Testing {0}\n\n"
                 "In:\n"
                 "  {1!r}\n"
                 "Expected:\n"
                 "  {2!r}\n"
                 "Got:\n"
                 "  {3!r}\n")
 def check_pairs(func, pairs):
     """Utility function for the common case of checking a function with a
     sequence of input/output pairs.
 
     Parameters
     ----------
     func : callable
       The function to be tested. Should accept a single argument.
     pairs : iterable
       A list of (input, expected_output) tuples.
 
     Returns
     -------
     None. Raises an AssertionError if any output does not match the expected
     value.
     """
     name = getattr(func, "func_name", getattr(func, "__name__", "<unknown>"))
     for inp, expected in pairs:
         out = func(inp)
         assert out == expected, pair_fail_msg.format(name, inp, expected, out)
 
+
 if py3compat.PY3:
     MyStringIO = StringIO
 else:
     # In Python 2, stdout/stderr can have either bytes or unicode written to them,
     # so we need a class that can handle both.
     class MyStringIO(StringIO):
         def write(self, s):
             s = py3compat.cast_unicode(s, encoding=getdefaultencoding())
             super(MyStringIO, self).write(s)
 
 notprinted_msg = """Did not find {0!r} in printed output (on {1}):
 {2!r}"""
+
 class AssertPrints(object):
     """Context manager for testing that code prints certain text.
     
     Examples
     --------
     >>> with AssertPrints("abc", suppress=False):
     ...     print "abcd"
     ...     print "def"
     ... 
     abcd
     def
     """
     def __init__(self, s, channel='stdout', suppress=True):
         self.s = s
         self.channel = channel
         self.suppress = suppress
     
     def __enter__(self):
         self.orig_stream = getattr(sys, self.channel)
         self.buffer = MyStringIO()
         self.tee = Tee(self.buffer, channel=self.channel)
         setattr(sys, self.channel, self.buffer if self.suppress else self.tee)
     
     def __exit__(self, etype, value, traceback):
         self.tee.flush()
         setattr(sys, self.channel, self.orig_stream)
         printed = self.buffer.getvalue()
         assert self.s in printed, notprinted_msg.format(self.s, self.channel, printed)
         return False
     
 class AssertNotPrints(AssertPrints):
     """Context manager for checking that certain output *isn't* produced.
     
     Counterpart of AssertPrints"""
     def __exit__(self, etype, value, traceback):
         self.tee.flush()
         setattr(sys, self.channel, self.orig_stream)
         printed = self.buffer.getvalue()
         assert self.s not in printed, notprinted_msg.format(self.s, self.channel, printed)
         return False
 
 @contextmanager
 def mute_warn():
     from IPython.utils import warn
     save_warn = warn.warn
     warn.warn = lambda *a, **kw: None
     try:
         yield
     finally:
         warn.warn = save_warn
 
 @contextmanager
 def make_tempfile(name):
     """ Create an empty, named, temporary file for the duration of the context.
     """
     f = open(name, 'w')
     f.close()
     try:
         yield
     finally:
         os.unlink(name)