tools.py

"""Generic testing tools.

Authors
-------
- Fernando Perez <Fernando.Perez@berkeley.edu>
"""

from __future__ import absolute_import

#-----------------------------------------------------------------------------
#  Copyright (C) 2009-2011  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
from IPython.utils.io import temp_pyfile, Tee
from IPython.utils import py3compat
from IPython.utils.encoding import DEFAULT_ENCODING

from . import decorators as dec
from . import skipdoctest

#-----------------------------------------------------------------------------
# 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 = [ '--PromptManager.in_template=""',
                    '--PromptManager.in2_template=""',
                    '--PromptManager.out_template=""'
    ]
    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, err = getoutputerror(full_cmd)
    # `import readline` causes 'ESC[?1034h' to be output sometimes,
    # so strip that out before doing comparisons
    if out:
        out = re.sub(r'\x1b\[[^h]+h', '', out)
    return out, err


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, options)
    #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_equal(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_equal(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=DEFAULT_ENCODING)
            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)


@contextmanager
def monkeypatch(obj, name, attr):
    """
    Context manager to replace attribute named `name` in `obj` with `attr`.
    """
    orig = getattr(obj, name)
    setattr(obj, name, attr)
    yield
    setattr(obj, name, orig)