add testing.decorators to genutils

ipython_genutils/testing/decorators.py

@@ -0,0 +1,369 b''
+# -*- coding: utf-8 -*-
+"""Decorators for labeling test objects.
+
+Decorators that merely return a modified version of the original function
+object are straightforward.  Decorators that return a new function object need
+to use nose.tools.make_decorator(original_function)(decorator) in returning the
+decorator, in order to preserve metadata such as function name, setup and
+teardown functions and so on - see nose.tools for more information.
+
+This module provides a set of useful decorators meant to be ready to use in
+your own tests.  See the bottom of the file for the ready-made ones, and if you
+find yourself writing a new one that may be of generic use, add it here.
+
+Included decorators:
+
+
+Lightweight testing that remains unittest-compatible.
+
+- An @as_unittest decorator can be used to tag any normal parameter-less
+  function as a unittest TestCase.  Then, both nose and normal unittest will
+  recognize it as such.  This will make it easier to migrate away from Nose if
+  we ever need/want to while maintaining very lightweight tests.
+
+NOTE: This file contains IPython-specific decorators. Using the machinery in
+IPython.external.decorators, we import either numpy.testing.decorators if numpy is
+available, OR use equivalent code in IPython.external._decorators, which
+we've copied verbatim from numpy.
+
+"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import sys
+import os
+import tempfile
+import unittest
+
+from decorator import decorator
+
+# Expose the unittest-driven decorators
+from .ipunittest import ipdoctest, ipdocstring
+
+# Grab the numpy-specific decorators which we keep in a file that we
+# occasionally update from upstream: decorators.py is a copy of
+# numpy.testing.decorators, we expose all of it here.
+from IPython.external.decorators import *
+
+# For onlyif_cmd_exists decorator
+from IPython.utils.py3compat import string_types, which
+
+#-----------------------------------------------------------------------------
+# Classes and functions
+#-----------------------------------------------------------------------------
+
+# Simple example of the basic idea
+def as_unittest(func):
+    """Decorator to make a simple function into a normal test via unittest."""
+    class Tester(unittest.TestCase):
+        def test(self):
+            func()
+
+    Tester.__name__ = func.__name__
+
+    return Tester
+
+# Utility functions
+
+def apply_wrapper(wrapper,func):
+    """Apply a wrapper to a function for decoration.
+
+    This mixes Michele Simionato's decorator tool with nose's make_decorator,
+    to apply a wrapper in a decorator so that all nose attributes, as well as
+    function signature and other properties, survive the decoration cleanly.
+    This will ensure that wrapped functions can still be well introspected via
+    IPython, for example.
+    """
+    import nose.tools
+
+    return decorator(wrapper,nose.tools.make_decorator(func)(wrapper))
+
+
+def make_label_dec(label,ds=None):
+    """Factory function to create a decorator that applies one or more labels.
+
+    Parameters
+    ----------
+      label : string or sequence
+      One or more labels that will be applied by the decorator to the functions
+    it decorates.  Labels are attributes of the decorated function with their
+    value set to True.
+
+      ds : string
+      An optional docstring for the resulting decorator.  If not given, a
+      default docstring is auto-generated.
+
+    Returns
+    -------
+      A decorator.
+
+    Examples
+    --------
+
+    A simple labeling decorator:
+
+    >>> slow = make_label_dec('slow')
+    >>> slow.__doc__
+    "Labels a test as 'slow'."
+    
+    And one that uses multiple labels and a custom docstring:
+    
+    >>> rare = make_label_dec(['slow','hard'],
+    ... "Mix labels 'slow' and 'hard' for rare tests.")
+    >>> rare.__doc__
+    "Mix labels 'slow' and 'hard' for rare tests."
+
+    Now, let's test using this one:
+    >>> @rare
+    ... def f(): pass
+    ...
+    >>>
+    >>> f.slow
+    True
+    >>> f.hard
+    True
+    """
+
+    if isinstance(label, string_types):
+        labels = [label]
+    else:
+        labels = label
+
+    # Validate that the given label(s) are OK for use in setattr() by doing a
+    # dry run on a dummy function.
+    tmp = lambda : None
+    for label in labels:
+        setattr(tmp,label,True)
+
+    # This is the actual decorator we'll return
+    def decor(f):
+        for label in labels:
+            setattr(f,label,True)
+        return f
+
+    # Apply the user's docstring, or autogenerate a basic one
+    if ds is None:
+        ds = "Labels a test as %r." % label
+    decor.__doc__ = ds
+
+    return decor
+
+
+# Inspired by numpy's skipif, but uses the full apply_wrapper utility to
+# preserve function metadata better and allows the skip condition to be a
+# callable.
+def skipif(skip_condition, msg=None):
+    ''' Make function raise SkipTest exception if skip_condition is true
+
+    Parameters
+    ----------
+
+    skip_condition : bool or callable
+      Flag to determine whether to skip test. If the condition is a
+      callable, it is used at runtime to dynamically make the decision. This
+      is useful for tests that may require costly imports, to delay the cost
+      until the test suite is actually executed.
+    msg : string
+      Message to give on raising a SkipTest exception.
+
+    Returns
+    -------
+    decorator : function
+      Decorator, which, when applied to a function, causes SkipTest
+      to be raised when the skip_condition was True, and the function
+      to be called normally otherwise.
+
+    Notes
+    -----
+    You will see from the code that we had to further decorate the
+    decorator with the nose.tools.make_decorator function in order to
+    transmit function name, and various other metadata.
+    '''
+
+    def skip_decorator(f):
+        # Local import to avoid a hard nose dependency and only incur the
+        # import time overhead at actual test-time.
+        import nose
+
+        # Allow for both boolean or callable skip conditions.
+        if callable(skip_condition):
+            skip_val = skip_condition
+        else:
+            skip_val = lambda : skip_condition
+
+        def get_msg(func,msg=None):
+            """Skip message with information about function being skipped."""
+            if msg is None: out = 'Test skipped due to test condition.'
+            else: out = msg
+            return "Skipping test: %s. %s" % (func.__name__,out)
+
+        # We need to define *two* skippers because Python doesn't allow both
+        # return with value and yield inside the same function.
+        def skipper_func(*args, **kwargs):
+            """Skipper for normal test functions."""
+            if skip_val():
+                raise nose.SkipTest(get_msg(f,msg))
+            else:
+                return f(*args, **kwargs)
+
+        def skipper_gen(*args, **kwargs):
+            """Skipper for test generators."""
+            if skip_val():
+                raise nose.SkipTest(get_msg(f,msg))
+            else:
+                for x in f(*args, **kwargs):
+                    yield x
+
+        # Choose the right skipper to use when building the actual generator.
+        if nose.util.isgenerator(f):
+            skipper = skipper_gen
+        else:
+            skipper = skipper_func
+
+        return nose.tools.make_decorator(f)(skipper)
+
+    return skip_decorator
+
+# A version with the condition set to true, common case just to attach a message
+# to a skip decorator
+def skip(msg=None):
+    """Decorator factory - mark a test function for skipping from test suite.
+
+    Parameters
+    ----------
+      msg : string
+        Optional message to be added.
+
+    Returns
+    -------
+       decorator : function
+         Decorator, which, when applied to a function, causes SkipTest
+         to be raised, with the optional message added.
+      """
+
+    return skipif(True,msg)
+
+
+def onlyif(condition, msg):
+    """The reverse from skipif, see skipif for details."""
+
+    if callable(condition):
+        skip_condition = lambda : not condition()
+    else:
+        skip_condition = lambda : not condition
+
+    return skipif(skip_condition, msg)
+
+#-----------------------------------------------------------------------------
+# Utility functions for decorators
+def module_not_available(module):
+    """Can module be imported?  Returns true if module does NOT import.
+
+    This is used to make a decorator to skip tests that require module to be
+    available, but delay the 'import numpy' to test execution time.
+    """
+    try:
+        mod = __import__(module)
+        mod_not_avail = False
+    except ImportError:
+        mod_not_avail = True
+
+    return mod_not_avail
+
+
+def decorated_dummy(dec, name):
+    """Return a dummy function decorated with dec, with the given name.
+    
+    Examples
+    --------
+    import IPython.testing.decorators as dec
+    setup = dec.decorated_dummy(dec.skip_if_no_x11, __name__)
+    """
+    dummy = lambda: None
+    dummy.__name__ = name
+    return dec(dummy)
+
+#-----------------------------------------------------------------------------
+# Decorators for public use
+
+# Decorators to skip certain tests on specific platforms.
+skip_win32 = skipif(sys.platform == 'win32',
+                    "This test does not run under Windows")
+skip_linux = skipif(sys.platform.startswith('linux'),
+                    "This test does not run under Linux")
+skip_osx = skipif(sys.platform == 'darwin',"This test does not run under OS X")
+
+
+# Decorators to skip tests if not on specific platforms.
+skip_if_not_win32 = skipif(sys.platform != 'win32',
+                           "This test only runs under Windows")
+skip_if_not_linux = skipif(not sys.platform.startswith('linux'),
+                           "This test only runs under Linux")
+skip_if_not_osx = skipif(sys.platform != 'darwin',
+                         "This test only runs under OSX")
+
+
+_x11_skip_cond = (sys.platform not in ('darwin', 'win32') and
+                  os.environ.get('DISPLAY', '') == '')
+_x11_skip_msg = "Skipped under *nix when X11/XOrg not available"
+
+skip_if_no_x11 = skipif(_x11_skip_cond, _x11_skip_msg)
+
+# not a decorator itself, returns a dummy function to be used as setup
+def skip_file_no_x11(name):
+    return decorated_dummy(skip_if_no_x11, name) if _x11_skip_cond else None
+
+# Other skip decorators
+
+# generic skip without module
+skip_without = lambda mod: skipif(module_not_available(mod), "This test requires %s" % mod)
+
+skipif_not_numpy = skip_without('numpy')
+
+skipif_not_matplotlib = skip_without('matplotlib')
+
+skipif_not_sympy = skip_without('sympy')
+
+skip_known_failure = knownfailureif(True,'This test is known to fail')
+
+known_failure_py3 = knownfailureif(sys.version_info[0] >= 3, 
+                                    'This test is known to fail on Python 3.')
+
+# A null 'decorator', useful to make more readable code that needs to pick
+# between different decorators based on OS or other conditions
+null_deco = lambda f: f
+
+# Some tests only run where we can use unicode paths. Note that we can't just
+# check os.path.supports_unicode_filenames, which is always False on Linux.
+try:
+    f = tempfile.NamedTemporaryFile(prefix=u"tmp€")
+except UnicodeEncodeError:
+    unicode_paths = False
+else:
+    unicode_paths = True
+    f.close()
+
+onlyif_unicode_paths = onlyif(unicode_paths, ("This test is only applicable "
+                                    "where we can use unicode in filenames."))
+
+
+def onlyif_cmds_exist(*commands):
+    """
+    Decorator to skip test when at least one of `commands` is not found.
+    """
+    for cmd in commands:
+        if not which(cmd):
+            return skip("This test runs only if command '{0}' "
+                        "is installed".format(cmd))
+    return null_deco
+
+def onlyif_any_cmd_exists(*commands):
+    """
+    Decorator to skip test unless at least one of `commands` is found.
+    """
+    for cmd in commands:
+        if which(cmd):
+            return null_deco
+    return skip("This test runs only if one of the commands {0} "
+                "is installed".format(commands))