IPython/testing/tools.py

"""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)