
``unittest`` --- Unit testing framework
***************************************

New in version 2.1.

(If you are already familiar with the basic concepts of testing, you
might want to skip to *the list of assert methods*.)

The Python unit testing framework, sometimes referred to as "PyUnit,"
is a Python language version of JUnit, by Kent Beck and Erich Gamma.
JUnit is, in turn, a Java version of Kent's Smalltalk testing
framework.  Each is the de facto standard unit testing framework for
its respective language.

``unittest`` supports test automation, sharing of setup and shutdown
code for tests, aggregation of tests into collections, and
independence of the tests from the reporting framework.  The
``unittest`` module provides classes that make it easy to support
these qualities for a set of tests.

To achieve this, ``unittest`` supports some important concepts:

test fixture
   A *test fixture* represents the preparation needed to perform one
   or more tests, and any associate cleanup actions.  This may
   involve, for example, creating temporary or proxy databases,
   directories, or starting a server process.

test case
   A *test case* is the smallest unit of testing.  It checks for a
   specific response to a particular set of inputs.  ``unittest``
   provides a base class, ``TestCase``, which may be used to create
   new test cases.

test suite
   A *test suite* is a collection of test cases, test suites, or both.
   It is used to aggregate tests that should be executed together.

test runner
   A *test runner* is a component which orchestrates the execution of
   tests and provides the outcome to the user.  The runner may use a
   graphical interface, a textual interface, or return a special value
   to indicate the results of executing the tests.

The test case and test fixture concepts are supported through the
``TestCase`` and ``FunctionTestCase`` classes; the former should be
used when creating new tests, and the latter can be used when
integrating existing test code with a ``unittest``-driven framework.
When building test fixtures using ``TestCase``, the ``setUp()`` and
``tearDown()`` methods can be overridden to provide initialization and
cleanup for the fixture.  With ``FunctionTestCase``, existing
functions can be passed to the constructor for these purposes.  When
the test is run, the fixture initialization is run first; if it
succeeds, the cleanup method is run after the test has been executed,
regardless of the outcome of the test.  Each instance of the
``TestCase`` will only be used to run a single test method, so a new
fixture is created for each test.

Test suites are implemented by the ``TestSuite`` class.  This class
allows individual tests and test suites to be aggregated; when the
suite is executed, all tests added directly to the suite and in
"child" test suites are run.

A test runner is an object that provides a single method, ``run()``,
which accepts a ``TestCase`` or ``TestSuite`` object as a parameter,
and returns a result object.  The class ``TestResult`` is provided for
use as the result object. ``unittest`` provides the ``TextTestRunner``
as an example test runner which reports test results on the standard
error stream by default.  Alternate runners can be implemented for
other environments (such as graphical environments) without any need
to derive from a specific class.

See also:

   Module ``doctest``
      Another test-support module with a very different flavor.

   unittest2: A backport of new unittest features for Python 2.4-2.6
      Many new features were added to unittest in Python 2.7,
      including test discovery. unittest2 allows you to use these
      features with earlier versions of Python.

   Simple Smalltalk Testing: With Patterns
      Kent Beck's original paper on testing frameworks using the
      pattern shared by ``unittest``.

   Nose and py.test
      Third-party unittest frameworks with a lighter-weight syntax for
      writing tests.  For example, ``assert func(10) == 42``.

   The Python Testing Tools Taxonomy
      An extensive list of Python testing tools including functional
      testing frameworks and mock object libraries.

   Testing in Python Mailing List
      A special-interest-group for discussion of testing, and testing
      tools, in Python.


Basic example
=============

The ``unittest`` module provides a rich set of tools for constructing
and running tests.  This section demonstrates that a small subset of
the tools suffice to meet the needs of most users.

Here is a short script to test three functions from the ``random``
module:

   import random
   import unittest

   class TestSequenceFunctions(unittest.TestCase):

       def setUp(self):
           self.seq = range(10)

       def test_shuffle(self):
           # make sure the shuffled sequence does not lose any elements
           random.shuffle(self.seq)
           self.seq.sort()
           self.assertEqual(self.seq, range(10))

           # should raise an exception for an immutable sequence
           self.assertRaises(TypeError, random.shuffle, (1,2,3))

       def test_choice(self):
           element = random.choice(self.seq)
           self.assertTrue(element in self.seq)

       def test_sample(self):
           with self.assertRaises(ValueError):
               random.sample(self.seq, 20)
           for element in random.sample(self.seq, 5):
               self.assertTrue(element in self.seq)

   if __name__ == '__main__':
       unittest.main()

A testcase is created by subclassing ``unittest.TestCase``.  The three
individual tests are defined with methods whose names start with the
letters ``test``.  This naming convention informs the test runner
about which methods represent tests.

The crux of each test is a call to ``assertEqual()`` to check for an
expected result; ``assertTrue()`` to verify a condition; or
``assertRaises()`` to verify that an expected exception gets raised.
These methods are used instead of the ``assert`` statement so the test
runner can accumulate all test results and produce a report.

When a ``setUp()`` method is defined, the test runner will run that
method prior to each test.  Likewise, if a ``tearDown()`` method is
defined, the test runner will invoke that method after each test.  In
the example, ``setUp()`` was used to create a fresh sequence for each
test.

The final block shows a simple way to run the tests.
``unittest.main()`` provides a command-line interface to the test
script.  When run from the command line, the above script produces an
output that looks like this:

   ...
   ----------------------------------------------------------------------
   Ran 3 tests in 0.000s

   OK

Instead of ``unittest.main()``, there are other ways to run the tests
with a finer level of control, less terse output, and no requirement
to be run from the command line.  For example, the last two lines may
be replaced with:

   suite = unittest.TestLoader().loadTestsFromTestCase(TestSequenceFunctions)
   unittest.TextTestRunner(verbosity=2).run(suite)

Running the revised script from the interpreter or another script
produces the following output:

   test_choice (__main__.TestSequenceFunctions) ... ok
   test_sample (__main__.TestSequenceFunctions) ... ok
   test_shuffle (__main__.TestSequenceFunctions) ... ok

   ----------------------------------------------------------------------
   Ran 3 tests in 0.110s

   OK

The above examples show the most commonly used ``unittest`` features
which are sufficient to meet many everyday testing needs.  The
remainder of the documentation explores the full feature set from
first principles.


Command-Line Interface
======================

The unittest module can be used from the command line to run tests
from modules, classes or even individual test methods:

   python -m unittest test_module1 test_module2
   python -m unittest test_module.TestClass
   python -m unittest test_module.TestClass.test_method

You can pass in a list with any combination of module names, and fully
qualified class or method names.

You can run tests with more detail (higher verbosity) by passing in
the -v flag:

   python -m unittest -v test_module

For a list of all the command-line options:

   python -m unittest -h

Changed in version 2.7: In earlier versions it was only possible to
run individual test methods and not modules or classes.


Command-line options
--------------------

**unittest** supports these command-line options:

-b, --buffer

   The standard output and standard error streams are buffered during
   the test run. Output during a passing test is discarded. Output is
   echoed normally on test fail or error and is added to the failure
   messages.

-c, --catch

   Control-C during the test run waits for the current test to end and
   then reports all the results so far. A second control-C raises the
   normal ``KeyboardInterrupt`` exception.

   See Signal Handling for the functions that provide this
   functionality.

-f, --failfast

   Stop the test run on the first error or failure.

New in version 2.7: The command-line options ``-b``, ``-c`` and ``-f``
were added.

The command line can also be used for test discovery, for running all
of the tests in a project or just a subset.


Test Discovery
==============

New in version 2.7.

Unittest supports simple test discovery. In order to be compatible
with test discovery, all of the test files must be *modules* or
*packages* importable from the top-level directory of the project
(this means that their filenames must be valid *identifiers*).

Test discovery is implemented in ``TestLoader.discover()``, but can
also be used from the command line. The basic command-line usage is:

   cd project_directory
   python -m unittest discover

The ``discover`` sub-command has the following options:

-v, --verbose

   Verbose output

-s, --start-directory directory

   Directory to start discovery (``.`` default)

-p, --pattern pattern

   Pattern to match test files (``test*.py`` default)

-t, --top-level-directory directory

   Top level directory of project (defaults to start directory)

The *-s*, *-p*, and *-t* options can be passed in as positional
arguments in that order. The following two command lines are
equivalent:

   python -m unittest discover -s project_directory -p '*_test.py'
   python -m unittest discover project_directory '*_test.py'

As well as being a path it is possible to pass a package name, for
example ``myproject.subpackage.test``, as the start directory. The
package name you supply will then be imported and its location on the
filesystem will be used as the start directory.

Caution: Test discovery loads tests by importing them. Once test discovery
  has found all the test files from the start directory you specify it
  turns the paths into package names to import. For example
  ``foo/bar/baz.py`` will be imported as ``foo.bar.baz``.If you have a
  package installed globally and attempt test discovery on a different
  copy of the package then the import *could* happen from the wrong
  place. If this happens test discovery will warn you and exit.If you
  supply the start directory as a package name rather than a path to a
  directory then discover assumes that whichever location it imports
  from is the location you intended, so you will not get the warning.

Test modules and packages can customize test loading and discovery by
through the load_tests protocol.


Organizing test code
====================

The basic building blocks of unit testing are *test cases* --- single
scenarios that must be set up and checked for correctness.  In
``unittest``, test cases are represented by instances of
``unittest``'s ``TestCase`` class. To make your own test cases you
must write subclasses of ``TestCase``, or use ``FunctionTestCase``.

An instance of a ``TestCase``-derived class is an object that can
completely run a single test method, together with optional set-up and
tidy-up code.

The testing code of a ``TestCase`` instance should be entirely self
contained, such that it can be run either in isolation or in arbitrary
combination with any number of other test cases.

The simplest ``TestCase`` subclass will simply override the
``runTest()`` method in order to perform specific testing code:

   import unittest

   class DefaultWidgetSizeTestCase(unittest.TestCase):
       def runTest(self):
           widget = Widget('The widget')
           self.assertEqual(widget.size(), (50, 50), 'incorrect default size')

Note that in order to test something, we use one of the ``assert*()``
methods provided by the ``TestCase`` base class.  If the test fails,
an exception will be raised, and ``unittest`` will identify the test
case as a *failure*.  Any other exceptions will be treated as
*errors*. This helps you identify where the problem is: *failures* are
caused by incorrect results - a 5 where you expected a 6. *Errors* are
caused by incorrect code - e.g., a ``TypeError`` caused by an
incorrect function call.

The way to run a test case will be described later.  For now, note
that to construct an instance of such a test case, we call its
constructor without arguments:

   testCase = DefaultWidgetSizeTestCase()

Now, such test cases can be numerous, and their set-up can be
repetitive.  In the above case, constructing a ``Widget`` in each of
100 Widget test case subclasses would mean unsightly duplication.

Luckily, we can factor out such set-up code by implementing a method
called ``setUp()``, which the testing framework will automatically
call for us when we run the test:

   import unittest

   class SimpleWidgetTestCase(unittest.TestCase):
       def setUp(self):
           self.widget = Widget('The widget')

   class DefaultWidgetSizeTestCase(SimpleWidgetTestCase):
       def runTest(self):
           self.assertEqual(self.widget.size(), (50,50),
                            'incorrect default size')

   class WidgetResizeTestCase(SimpleWidgetTestCase):
       def runTest(self):
           self.widget.resize(100,150)
           self.assertEqual(self.widget.size(), (100,150),
                            'wrong size after resize')

If the ``setUp()`` method raises an exception while the test is
running, the framework will consider the test to have suffered an
error, and the ``runTest()`` method will not be executed.

Similarly, we can provide a ``tearDown()`` method that tidies up after
the ``runTest()`` method has been run:

   import unittest

   class SimpleWidgetTestCase(unittest.TestCase):
       def setUp(self):
           self.widget = Widget('The widget')

       def tearDown(self):
           self.widget.dispose()
           self.widget = None

If ``setUp()`` succeeded, the ``tearDown()`` method will be run
whether ``runTest()`` succeeded or not.

Such a working environment for the testing code is called a *fixture*.

Often, many small test cases will use the same fixture.  In this case,
we would end up subclassing ``SimpleWidgetTestCase`` into many small
one-method classes such as ``DefaultWidgetSizeTestCase``.  This is
time-consuming and discouraging, so in the same vein as JUnit,
``unittest`` provides a simpler mechanism:

   import unittest

   class WidgetTestCase(unittest.TestCase):
       def setUp(self):
           self.widget = Widget('The widget')

       def tearDown(self):
           self.widget.dispose()
           self.widget = None

       def test_default_size(self):
           self.assertEqual(self.widget.size(), (50,50),
                            'incorrect default size')

       def test_resize(self):
           self.widget.resize(100,150)
           self.assertEqual(self.widget.size(), (100,150),
                            'wrong size after resize')

Here we have not provided a ``runTest()`` method, but have instead
provided two different test methods.  Class instances will now each
run one of the ``test_*()`` methods, with ``self.widget`` created and
destroyed separately for each instance.  When creating an instance we
must specify the test method it is to run.  We do this by passing the
method name in the constructor:

   defaultSizeTestCase = WidgetTestCase('test_default_size')
   resizeTestCase = WidgetTestCase('test_resize')

Test case instances are grouped together according to the features
they test. ``unittest`` provides a mechanism for this: the *test
suite*, represented by ``unittest``'s ``TestSuite`` class:

   widgetTestSuite = unittest.TestSuite()
   widgetTestSuite.addTest(WidgetTestCase('test_default_size'))
   widgetTestSuite.addTest(WidgetTestCase('test_resize'))

For the ease of running tests, as we will see later, it is a good idea
to provide in each test module a callable object that returns a pre-
built test suite:

   def suite():
       suite = unittest.TestSuite()
       suite.addTest(WidgetTestCase('test_default_size'))
       suite.addTest(WidgetTestCase('test_resize'))
       return suite

or even:

   def suite():
       tests = ['test_default_size', 'test_resize']

       return unittest.TestSuite(map(WidgetTestCase, tests))

Since it is a common pattern to create a ``TestCase`` subclass with
many similarly named test functions, ``unittest`` provides a
``TestLoader`` class that can be used to automate the process of
creating a test suite and populating it with individual tests. For
example,

   suite = unittest.TestLoader().loadTestsFromTestCase(WidgetTestCase)

will create a test suite that will run
``WidgetTestCase.test_default_size()`` and
``WidgetTestCase.test_resize``. ``TestLoader`` uses the ``'test'``
method name prefix to identify test methods automatically.

Note that the order in which the various test cases will be run is
determined by sorting the test function names with respect to the
built-in ordering for strings.

Often it is desirable to group suites of test cases together, so as to
run tests for the whole system at once.  This is easy, since
``TestSuite`` instances can be added to a ``TestSuite`` just as
``TestCase`` instances can be added to a ``TestSuite``:

   suite1 = module1.TheTestSuite()
   suite2 = module2.TheTestSuite()
   alltests = unittest.TestSuite([suite1, suite2])

You can place the definitions of test cases and test suites in the
same modules as the code they are to test (such as ``widget.py``), but
there are several advantages to placing the test code in a separate
module, such as ``test_widget.py``:

* The test module can be run standalone from the command line.

* The test code can more easily be separated from shipped code.

* There is less temptation to change test code to fit the code it
  tests without a good reason.

* Test code should be modified much less frequently than the code it
  tests.

* Tested code can be refactored more easily.

* Tests for modules written in C must be in separate modules anyway,
  so why not be consistent?

* If the testing strategy changes, there is no need to change the
  source code.


Re-using old test code
======================

Some users will find that they have existing test code that they would
like to run from ``unittest``, without converting every old test
function to a ``TestCase`` subclass.

For this reason, ``unittest`` provides a ``FunctionTestCase`` class.
This subclass of ``TestCase`` can be used to wrap an existing test
function.  Set-up and tear-down functions can also be provided.

Given the following test function:

   def testSomething():
       something = makeSomething()
       assert something.name is not None
       # ...

one can create an equivalent test case instance as follows:

   testcase = unittest.FunctionTestCase(testSomething)

If there are additional set-up and tear-down methods that should be
called as part of the test case's operation, they can also be provided
like so:

   testcase = unittest.FunctionTestCase(testSomething,
                                        setUp=makeSomethingDB,
                                        tearDown=deleteSomethingDB)

To make migrating existing test suites easier, ``unittest`` supports
tests raising ``AssertionError`` to indicate test failure. However, it
is recommended that you use the explicit ``TestCase.fail*()`` and
``TestCase.assert*()`` methods instead, as future versions of
``unittest`` may treat ``AssertionError`` differently.

Note: Even though ``FunctionTestCase`` can be used to quickly convert an
  existing test base over to a ``unittest``-based system, this
  approach is not recommended.  Taking the time to set up proper
  ``TestCase`` subclasses will make future test refactorings
  infinitely easier.

In some cases, the existing tests may have been written using the
``doctest`` module.  If so, ``doctest`` provides a ``DocTestSuite``
class that can automatically build ``unittest.TestSuite`` instances
from the existing ``doctest``-based tests.


Skipping tests and expected failures
====================================

New in version 2.7.

Unittest supports skipping individual test methods and even whole
classes of tests.  In addition, it supports marking a test as a
"expected failure," a test that is broken and will fail, but shouldn't
be counted as a failure on a ``TestResult``.

Skipping a test is simply a matter of using the ``skip()`` *decorator*
or one of its conditional variants.

Basic skipping looks like this:

   class MyTestCase(unittest.TestCase):

       @unittest.skip("demonstrating skipping")
       def test_nothing(self):
           self.fail("shouldn't happen")

       @unittest.skipIf(mylib.__version__ < (1, 3),
                        "not supported in this library version")
       def test_format(self):
           # Tests that work for only a certain version of the library.
           pass

       @unittest.skipUnless(sys.platform.startswith("win"), "requires Windows")
       def test_windows_support(self):
           # windows specific testing code
           pass

This is the output of running the example above in verbose mode:

   test_format (__main__.MyTestCase) ... skipped 'not supported in this library version'
   test_nothing (__main__.MyTestCase) ... skipped 'demonstrating skipping'
   test_windows_support (__main__.MyTestCase) ... skipped 'requires Windows'

   ----------------------------------------------------------------------
   Ran 3 tests in 0.005s

   OK (skipped=3)

Classes can be skipped just like methods:

   @unittest.skip("showing class skipping")
   class MySkippedTestCase(unittest.TestCase):
       def test_not_run(self):
           pass

``TestCase.setUp()`` can also skip the test.  This is useful when a
resource that needs to be set up is not available.

Expected failures use the ``expectedFailure()`` decorator.

   class ExpectedFailureTestCase(unittest.TestCase):
       @unittest.expectedFailure
       def test_fail(self):
           self.assertEqual(1, 0, "broken")

It's easy to roll your own skipping decorators by making a decorator
that calls ``skip()`` on the test when it wants it to be skipped.
This decorator skips the test unless the passed object has a certain
attribute:

   def skipUnlessHasattr(obj, attr):
       if hasattr(obj, attr):
           return lambda func: func
       return unittest.skip("{!r} doesn't have {!r}".format(obj, attr))

The following decorators implement test skipping and expected
failures:

unittest.skip(reason)

   Unconditionally skip the decorated test.  *reason* should describe
   why the test is being skipped.

unittest.skipIf(condition, reason)

   Skip the decorated test if *condition* is true.

unittest.skipUnless(condition, reason)

   Skip the decorated test unless *condition* is true.

unittest.expectedFailure()

   Mark the test as an expected failure.  If the test fails when run,
   the test is not counted as a failure.

exception exception unittest.SkipTest(reason)

   This exception is raised to skip a test.

   Usually you can use ``TestCase.skipTest()`` or one of the skipping
   decorators instead of raising this directly.

Skipped tests will not have ``setUp()`` or ``tearDown()`` run around
them. Skipped classes will not have ``setUpClass()`` or
``tearDownClass()`` run.


Classes and functions
=====================

This section describes in depth the API of ``unittest``.


Test cases
----------

class class unittest.TestCase(methodName='runTest')

   Instances of the ``TestCase`` class represent the smallest testable
   units in the ``unittest`` universe.  This class is intended to be
   used as a base class, with specific tests being implemented by
   concrete subclasses.  This class implements the interface needed by
   the test runner to allow it to drive the test, and methods that the
   test code can use to check for and report various kinds of failure.

   Each instance of ``TestCase`` will run a single test method: the
   method named *methodName*.  If you remember, we had an earlier
   example that went something like this:

      def suite():
          suite = unittest.TestSuite()
          suite.addTest(WidgetTestCase('test_default_size'))
          suite.addTest(WidgetTestCase('test_resize'))
          return suite

   Here, we create two instances of ``WidgetTestCase``, each of which
   runs a single test.

   *methodName* defaults to ``runTest()``.

   ``TestCase`` instances provide three groups of methods: one group
   used to run the test, another used by the test implementation to
   check conditions and report failures, and some inquiry methods
   allowing information about the test itself to be gathered.

   Methods in the first group (running the test) are:

   setUp()

      Method called to prepare the test fixture.  This is called
      immediately before calling the test method; any exception raised
      by this method will be considered an error rather than a test
      failure. The default implementation does nothing.

   tearDown()

      Method called immediately after the test method has been called
      and the result recorded.  This is called even if the test method
      raised an exception, so the implementation in subclasses may
      need to be particularly careful about checking internal state.
      Any exception raised by this method will be considered an error
      rather than a test failure.  This method will only be called if
      the ``setUp()`` succeeds, regardless of the outcome of the test
      method. The default implementation does nothing.

   setUpClass()

      A class method called before tests in an individual class run.
      ``setUpClass`` is called with the class as the only argument and
      must be decorated as a ``classmethod()``:

         @classmethod
         def setUpClass(cls):
             ...

      See Class and Module Fixtures for more details.

      New in version 2.7.

   tearDownClass()

      A class method called after tests in an individual class have
      run. ``tearDownClass`` is called with the class as the only
      argument and must be decorated as a ``classmethod()``:

         @classmethod
         def tearDownClass(cls):
             ...

      See Class and Module Fixtures for more details.

      New in version 2.7.

   run(result=None)

      Run the test, collecting the result into the test result object
      passed as *result*.  If *result* is omitted or ``None``, a
      temporary result object is created (by calling the
      ``defaultTestResult()`` method) and used. The result object is
      not returned to ``run()``'s caller.

      The same effect may be had by simply calling the ``TestCase``
      instance.

   skipTest(reason)

      Calling this during a test method or ``setUp()`` skips the
      current test.  See *Skipping tests and expected failures* for
      more information.

      New in version 2.7.

   debug()

      Run the test without collecting the result.  This allows
      exceptions raised by the test to be propagated to the caller,
      and can be used to support running tests under a debugger.

   The ``TestCase`` class provides a number of methods to check for
   and report failures, such as:

   +-------------------------------------------+-------------------------------+-----------------+
   | Method                                    | Checks that                   | New in          |
   +===========================================+===============================+=================+
   | ``assertEqual(a, b)``                     | ``a == b``                    |                 |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertNotEqual(a, b)``                  | ``a != b``                    |                 |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertTrue(x)``                         | ``bool(x) is True``           |                 |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertFalse(x)``                        | ``bool(x) is False``          |                 |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertIs(a, b)``                        | ``a is b``                    | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertIsNot(a, b)``                     | ``a is not b``                | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertIsNone(x)``                       | ``x is None``                 | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertIsNotNone(x)``                    | ``x is not None``             | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertIn(a, b)``                        | ``a in b``                    | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertNotIn(a, b)``                     | ``a not in b``                | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertIsInstance(a, b)``                | ``isinstance(a, b)``          | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+
   | ``assertNotIsInstance(a, b)``             | ``not isinstance(a, b)``      | 2.7             |
   +-------------------------------------------+-------------------------------+-----------------+

   All the assert methods (except ``assertRaises()``,
   ``assertRaisesRegexp()``) accept a *msg* argument that, if
   specified, is used as the error message on failure (see also
   ``longMessage``).

   assertEqual(first, second, msg=None)

      Test that *first* and *second* are equal.  If the values do not
      compare equal, the test will fail.

      In addition, if *first* and *second* are the exact same type and
      one of list, tuple, dict, set, frozenset or unicode or any type
      that a subclass registers with ``addTypeEqualityFunc()`` the
      type-specific equality function will be called in order to
      generate a more useful default error message (see also the *list
      of type-specific methods*).

      Changed in version 2.7: Added the automatic calling of type-
      specific equality function.

   assertNotEqual(first, second, msg=None)

      Test that *first* and *second* are not equal.  If the values do
      compare equal, the test will fail.

   assertTrue(expr, msg=None)
   assertFalse(expr, msg=None)

      Test that *expr* is true (or false).

      Note that this is equivalent to ``bool(expr) is True`` and not
      to ``expr is True`` (use ``assertIs(expr, True)`` for the
      latter).  This method should also be avoided when more specific
      methods are available (e.g. ``assertEqual(a, b)`` instead of
      ``assertTrue(a == b)``), because they provide a better error
      message in case of failure.

   assertIs(first, second, msg=None)
   assertIsNot(first, second, msg=None)

      Test that *first* and *second* evaluate (or don't evaluate) to
      the same object.

      New in version 2.7.

   assertIsNone(expr, msg=None)
   assertIsNotNone(expr, msg=None)

      Test that *expr* is (or is not) None.

      New in version 2.7.

   assertIn(first, second, msg=None)
   assertNotIn(first, second, msg=None)

      Test that *first* is (or is not) in *second*.

      New in version 2.7.

   assertIsInstance(obj, cls, msg=None)
   assertNotIsInstance(obj, cls, msg=None)

      Test that *obj* is (or is not) an instance of *cls* (which can
      be a class or a tuple of classes, as supported by
      ``isinstance()``). To check for the exact type, use
      ``assertIs(type(obj), cls)``.

      New in version 2.7.

   It is also possible to check that exceptions and warnings are
   raised using the following methods:

   +-----------------------------------------------------------+----------------------------------------+--------------+
   | Method                                                    | Checks that                            | New in       |
   +===========================================================+========================================+==============+
   | ``assertRaises(exc, fun, *args, **kwds)``                 | ``fun(*args, **kwds)`` raises *exc*    |              |
   +-----------------------------------------------------------+----------------------------------------+--------------+
   | ``assertRaisesRegexp(exc, re, fun, *args, **kwds)``       | ``fun(*args, **kwds)`` raises *exc*    | 2.7          |
   |                                                           | and the message matches *re*           |              |
   +-----------------------------------------------------------+----------------------------------------+--------------+

   assertRaises(exception, callable, *args, **kwds)
   assertRaises(exception)

      Test that an exception is raised when *callable* is called with
      any positional or keyword arguments that are also passed to
      ``assertRaises()``.  The test passes if *exception* is raised,
      is an error if another exception is raised, or fails if no
      exception is raised. To catch any of a group of exceptions, a
      tuple containing the exception classes may be passed as
      *exception*.

      If only the *exception* argument is given, returns a context
      manager so that the code under test can be written inline rather
      than as a function:

         with self.assertRaises(SomeException):
             do_something()

      The context manager will store the caught exception object in
      its ``exception`` attribute.  This can be useful if the
      intention is to perform additional checks on the exception
      raised:

         with self.assertRaises(SomeException) as cm:
             do_something()

         the_exception = cm.exception
         self.assertEqual(the_exception.error_code, 3)

      Changed in version 2.7: Added the ability to use
      ``assertRaises()`` as a context manager.

   assertRaisesRegexp(exception, regexp, callable, *args, **kwds)
   assertRaisesRegexp(exception, regexp)

      Like ``assertRaises()`` but also tests that *regexp* matches on
      the string representation of the raised exception.  *regexp* may
      be a regular expression object or a string containing a regular
      expression suitable for use by ``re.search()``.  Examples:

         self.assertRaisesRegexp(ValueError, 'invalid literal for.*XYZ$',
                                 int, 'XYZ')

      or:

         with self.assertRaisesRegexp(ValueError, 'literal'):
            int('XYZ')

      New in version 2.7.

   There are also other methods used to perform more specific checks,
   such as:

   +-----------------------------------------+----------------------------------+----------------+
   | Method                                  | Checks that                      | New in         |
   +=========================================+==================================+================+
   | ``assertAlmostEqual(a, b)``             | ``round(a-b, 7) == 0``           |                |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertNotAlmostEqual(a, b)``          | ``round(a-b, 7) != 0``           |                |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertGreater(a, b)``                 | ``a > b``                        | 2.7            |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertGreaterEqual(a, b)``            | ``a >= b``                       | 2.7            |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertLess(a, b)``                    | ``a < b``                        | 2.7            |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertLessEqual(a, b)``               | ``a <= b``                       | 2.7            |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertRegexpMatches(s, re)``          | ``regex.search(s)``              | 2.7            |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertNotRegexpMatches(s, re)``       | ``not regex.search(s)``          | 2.7            |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertItemsEqual(a, b)``              | sorted(a) == sorted(b) and works | 2.7            |
   |                                         | with unhashable objs             |                |
   +-----------------------------------------+----------------------------------+----------------+
   | ``assertDictContainsSubset(a, b)``      | all the key/value pairs in *a*   | 2.7            |
   |                                         | exist in *b*                     |                |
   +-----------------------------------------+----------------------------------+----------------+

   assertAlmostEqual(first, second, places=7, msg=None, delta=None)
   assertNotAlmostEqual(first, second, places=7, msg=None, delta=None)

      Test that *first* and *second* are approximately (or not
      approximately) equal by computing the difference, rounding to
      the given number of decimal *places* (default 7), and comparing
      to zero.  Note that these methods round the values to the given
      number of *decimal places* (i.e. like the ``round()`` function)
      and not *significant digits*.

      If *delta* is supplied instead of *places* then the difference
      between *first* and *second* must be less (or more) than
      *delta*.

      Supplying both *delta* and *places* raises a ``TypeError``.

      Changed in version 2.7: ``assertAlmostEqual()`` automatically
      considers almost equal objects that compare equal.
      ``assertNotAlmostEqual()`` automatically fails if the objects
      compare equal.  Added the *delta* keyword argument.

   assertGreater(first, second, msg=None)
   assertGreaterEqual(first, second, msg=None)
   assertLess(first, second, msg=None)
   assertLessEqual(first, second, msg=None)

      Test that *first* is respectively >, >=, < or <= than *second*
      depending on the method name.  If not, the test will fail:

         >>> self.assertGreaterEqual(3, 4)
         AssertionError: "3" unexpectedly not greater than or equal to "4"

      New in version 2.7.

   assertRegexpMatches(text, regexp, msg=None)

      Test that a *regexp* search matches *text*.  In case of failure,
      the error message will include the pattern and the *text* (or
      the pattern and the part of *text* that unexpectedly matched).
      *regexp* may be a regular expression object or a string
      containing a regular expression suitable for use by
      ``re.search()``.

      New in version 2.7.

   assertNotRegexpMatches(text, regexp, msg=None)

      Verifies that a *regexp* search does not match *text*.  Fails
      with an error message including the pattern and the part of
      *text* that matches.  *regexp* may be a regular expression
      object or a string containing a regular expression suitable for
      use by ``re.search()``.

      New in version 2.7.

   assertItemsEqual(actual, expected, msg=None)

      Test that sequence *expected* contains the same elements as
      *actual*, regardless of their order. When they don't, an error
      message listing the differences between the sequences will be
      generated.

      Duplicate elements are *not* ignored when comparing *actual* and
      *expected*. It verifies if each element has the same count in
      both sequences. It is the equivalent of
      ``assertEqual(sorted(expected), sorted(actual))`` but it works
      with sequences of unhashable objects as well.

      In Python 3, this method is named ``assertCountEqual``.

      New in version 2.7.

   assertDictContainsSubset(expected, actual, msg=None)

      Tests whether the key/value pairs in dictionary *actual* are a
      superset of those in *expected*.  If not, an error message
      listing the missing keys and mismatched values is generated.

      New in version 2.7.

      Deprecated since version 3.2.

   The ``assertEqual()`` method dispatches the equality check for
   objects of the same type to different type-specific methods.  These
   methods are already implemented for most of the built-in types, but
   it's also possible to register new methods using
   ``addTypeEqualityFunc()``:

   addTypeEqualityFunc(typeobj, function)

      Registers a type-specific method called by ``assertEqual()`` to
      check if two objects of exactly the same *typeobj* (not
      subclasses) compare equal.  *function* must take two positional
      arguments and a third msg=None keyword argument just as
      ``assertEqual()`` does.  It must raise
      ``self.failureException(msg)`` when inequality between the first
      two parameters is detected -- possibly providing useful
      information and explaining the inequalities in details in the
      error message.

      New in version 2.7.

   The list of type-specific methods automatically used by
   ``assertEqual()`` are summarized in the following table.  Note that
   it's usually not necessary to invoke these methods directly.

   +-------------------------------------------+-------------------------------+----------------+
   | Method                                    | Used to compare               | New in         |
   +===========================================+===============================+================+
   | ``assertMultiLineEqual(a, b)``            | strings                       | 2.7            |
   +-------------------------------------------+-------------------------------+----------------+
   | ``assertSequenceEqual(a, b)``             | sequences                     | 2.7            |
   +-------------------------------------------+-------------------------------+----------------+
   | ``assertListEqual(a, b)``                 | lists                         | 2.7            |
   +-------------------------------------------+-------------------------------+----------------+
   | ``assertTupleEqual(a, b)``                | tuples                        | 2.7            |
   +-------------------------------------------+-------------------------------+----------------+
   | ``assertSetEqual(a, b)``                  | sets or frozensets            | 2.7            |
   +-------------------------------------------+-------------------------------+----------------+
   | ``assertDictEqual(a, b)``                 | dicts                         | 2.7            |
   +-------------------------------------------+-------------------------------+----------------+

   assertMultiLineEqual(first, second, msg=None)

      Test that the multiline string *first* is equal to the string
      *second*. When not equal a diff of the two strings highlighting
      the differences will be included in the error message. This
      method is used by default when comparing strings with
      ``assertEqual()``.

      New in version 2.7.

   assertSequenceEqual(seq1, seq2, msg=None, seq_type=None)

      Tests that two sequences are equal.  If a *seq_type* is
      supplied, both *seq1* and *seq2* must be instances of *seq_type*
      or a failure will be raised.  If the sequences are different an
      error message is constructed that shows the difference between
      the two.

      This method is not called directly by ``assertEqual()``, but
      it's used to implement ``assertListEqual()`` and
      ``assertTupleEqual()``.

      New in version 2.7.

   assertListEqual(list1, list2, msg=None)
   assertTupleEqual(tuple1, tuple2, msg=None)

      Tests that two lists or tuples are equal.  If not, an error
      message is constructed that shows only the differences between
      the two.  An error is also raised if either of the parameters
      are of the wrong type. These methods are used by default when
      comparing lists or tuples with ``assertEqual()``.

      New in version 2.7.

   assertSetEqual(set1, set2, msg=None)

      Tests that two sets are equal.  If not, an error message is
      constructed that lists the differences between the sets.  This
      method is used by default when comparing sets or frozensets with
      ``assertEqual()``.

      Fails if either of *set1* or *set2* does not have a
      ``set.difference()`` method.

      New in version 2.7.

   assertDictEqual(expected, actual, msg=None)

      Test that two dictionaries are equal.  If not, an error message
      is constructed that shows the differences in the dictionaries.
      This method will be used by default to compare dictionaries in
      calls to ``assertEqual()``.

      New in version 2.7.

   Finally the ``TestCase`` provides the following methods and
   attributes:

   fail(msg=None)

      Signals a test failure unconditionally, with *msg* or ``None``
      for the error message.

   failureException

      This class attribute gives the exception raised by the test
      method.  If a test framework needs to use a specialized
      exception, possibly to carry additional information, it must
      subclass this exception in order to "play fair" with the
      framework.  The initial value of this attribute is
      ``AssertionError``.

   longMessage

      If set to ``True`` then any explicit failure message you pass in
      to the *assert methods* will be appended to the end of the
      normal failure message.  The normal messages contain useful
      information about the objects involved, for example the message
      from assertEqual shows you the repr of the two unequal objects.
      Setting this attribute to ``True`` allows you to have a custom
      error message in addition to the normal one.

      This attribute defaults to ``False``, meaning that a custom
      message passed to an assert method will silence the normal
      message.

      The class setting can be overridden in individual tests by
      assigning an instance attribute to ``True`` or ``False`` before
      calling the assert methods.

      New in version 2.7.

   maxDiff

      This attribute controls the maximum length of diffs output by
      assert methods that report diffs on failure. It defaults to 80*8
      characters. Assert methods affected by this attribute are
      ``assertSequenceEqual()`` (including all the sequence comparison
      methods that delegate to it), ``assertDictEqual()`` and
      ``assertMultiLineEqual()``.

      Setting ``maxDiff`` to None means that there is no maximum
      length of diffs.

      New in version 2.7.

   Testing frameworks can use the following methods to collect
   information on the test:

   countTestCases()

      Return the number of tests represented by this test object.  For
      ``TestCase`` instances, this will always be ``1``.

   defaultTestResult()

      Return an instance of the test result class that should be used
      for this test case class (if no other result instance is
      provided to the ``run()`` method).

      For ``TestCase`` instances, this will always be an instance of
      ``TestResult``; subclasses of ``TestCase`` should override this
      as necessary.

   id()

      Return a string identifying the specific test case.  This is
      usually the full name of the test method, including the module
      and class name.

   shortDescription()

      Returns a description of the test, or ``None`` if no description
      has been provided.  The default implementation of this method
      returns the first line of the test method's docstring, if
      available, or ``None``.

   addCleanup(function, *args, **kwargs)

      Add a function to be called after ``tearDown()`` to cleanup
      resources used during the test. Functions will be called in
      reverse order to the order they are added (LIFO). They are
      called with any arguments and keyword arguments passed into
      ``addCleanup()`` when they are added.

      If ``setUp()`` fails, meaning that ``tearDown()`` is not called,
      then any cleanup functions added will still be called.

      New in version 2.7.

   doCleanups()

      This method is called unconditionally after ``tearDown()``, or
      after ``setUp()`` if ``setUp()`` raises an exception.

      It is responsible for calling all the cleanup functions added by
      ``addCleanup()``. If you need cleanup functions to be called
      *prior* to ``tearDown()`` then you can call ``doCleanups()``
      yourself.

      ``doCleanups()`` pops methods off the stack of cleanup functions
      one at a time, so it can be called at any time.

      New in version 2.7.

class class unittest.FunctionTestCase(testFunc, setUp=None, tearDown=None, description=None)

   This class implements the portion of the ``TestCase`` interface
   which allows the test runner to drive the test, but does not
   provide the methods which test code can use to check and report
   errors.  This is used to create test cases using legacy test code,
   allowing it to be integrated into a ``unittest``-based test
   framework.


Deprecated aliases
~~~~~~~~~~~~~~~~~~

For historical reasons, some of the ``TestCase`` methods had one or
more aliases that are now deprecated.  The following table lists the
correct names along with their deprecated aliases:

   +--------------------------------+---------------------------------+
   | Method Name                    | Deprecated alias(es)            |
   +================================+=================================+
   | ``assertEqual()``              | failUnlessEqual, assertEquals   |
   +--------------------------------+---------------------------------+
   | ``assertNotEqual()``           | failIfEqual                     |
   +--------------------------------+---------------------------------+
   | ``assertTrue()``               | failUnless, assert_             |
   +--------------------------------+---------------------------------+
   | ``assertFalse()``              | failIf                          |
   +--------------------------------+---------------------------------+
   | ``assertRaises()``             | failUnlessRaises                |
   +--------------------------------+---------------------------------+
   | ``assertAlmostEqual()``        | failUnlessAlmostEqual           |
   +--------------------------------+---------------------------------+
   | ``assertNotAlmostEqual()``     | failIfAlmostEqual               |
   +--------------------------------+---------------------------------+

   Deprecated since version 2.7: the aliases listed in the second
   column


Grouping tests
--------------

class class unittest.TestSuite(tests=())

   This class represents an aggregation of individual tests cases and
   test suites. The class presents the interface needed by the test
   runner to allow it to be run as any other test case.  Running a
   ``TestSuite`` instance is the same as iterating over the suite,
   running each test individually.

   If *tests* is given, it must be an iterable of individual test
   cases or other test suites that will be used to build the suite
   initially. Additional methods are provided to add test cases and
   suites to the collection later on.

   ``TestSuite`` objects behave much like ``TestCase`` objects, except
   they do not actually implement a test.  Instead, they are used to
   aggregate tests into groups of tests that should be run together.
   Some additional methods are available to add tests to ``TestSuite``
   instances:

   addTest(test)

      Add a ``TestCase`` or ``TestSuite`` to the suite.

   addTests(tests)

      Add all the tests from an iterable of ``TestCase`` and
      ``TestSuite`` instances to this test suite.

      This is equivalent to iterating over *tests*, calling
      ``addTest()`` for each element.

   ``TestSuite`` shares the following methods with ``TestCase``:

   run(result)

      Run the tests associated with this suite, collecting the result
      into the test result object passed as *result*.  Note that
      unlike ``TestCase.run()``, ``TestSuite.run()`` requires the
      result object to be passed in.

   debug()

      Run the tests associated with this suite without collecting the
      result. This allows exceptions raised by the test to be
      propagated to the caller and can be used to support running
      tests under a debugger.

   countTestCases()

      Return the number of tests represented by this test object,
      including all individual tests and sub-suites.

   __iter__()

      Tests grouped by a ``TestSuite`` are always accessed by
      iteration. Subclasses can lazily provide tests by overriding
      ``__iter__()``. Note that this method maybe called several times
      on a single suite (for example when counting tests or comparing
      for equality) so the tests returned must be the same for
      repeated iterations.

      Changed in version 2.7: In earlier versions the ``TestSuite``
      accessed tests directly rather than through iteration, so
      overriding ``__iter__()`` wasn't sufficient for providing tests.

   In the typical usage of a ``TestSuite`` object, the ``run()``
   method is invoked by a ``TestRunner`` rather than by the end-user
   test harness.


Loading and running tests
-------------------------

class class unittest.TestLoader

   The ``TestLoader`` class is used to create test suites from classes
   and modules.  Normally, there is no need to create an instance of
   this class; the ``unittest`` module provides an instance that can
   be shared as ``unittest.defaultTestLoader``.  Using a subclass or
   instance, however, allows customization of some configurable
   properties.

   ``TestLoader`` objects have the following methods:

   loadTestsFromTestCase(testCaseClass)

      Return a suite of all tests cases contained in the
      ``TestCase``-derived ``testCaseClass``.

   loadTestsFromModule(module)

      Return a suite of all tests cases contained in the given module.
      This method searches *module* for classes derived from
      ``TestCase`` and creates an instance of the class for each test
      method defined for the class.

      Note: While using a hierarchy of ``TestCase``-derived classes can be
        convenient in sharing fixtures and helper functions, defining
        test methods on base classes that are not intended to be
        instantiated directly does not play well with this method.
        Doing so, however, can be useful when the fixtures are
        different and defined in subclasses.

      If a module provides a ``load_tests`` function it will be called
      to load the tests. This allows modules to customize test
      loading. This is the load_tests protocol.

      Changed in version 2.7: Support for ``load_tests`` added.

   loadTestsFromName(name, module=None)

      Return a suite of all tests cases given a string specifier.

      The specifier *name* is a "dotted name" that may resolve either
      to a module, a test case class, a test method within a test case
      class, a ``TestSuite`` instance, or a callable object which
      returns a ``TestCase`` or ``TestSuite`` instance.  These checks
      are applied in the order listed here; that is, a method on a
      possible test case class will be picked up as "a test method
      within a test case class", rather than "a callable object".

      For example, if you have a module ``SampleTests`` containing a
      ``TestCase``-derived class ``SampleTestCase`` with three test
      methods (``test_one()``, ``test_two()``, and ``test_three()``),
      the specifier ``'SampleTests.SampleTestCase'`` would cause this
      method to return a suite which will run all three test methods.
      Using the specifier ``'SampleTests.SampleTestCase.test_two'``
      would cause it to return a test suite which will run only the
      ``test_two()`` test method. The specifier can refer to modules
      and packages which have not been imported; they will be imported
      as a side-effect.

      The method optionally resolves *name* relative to the given
      *module*.

   loadTestsFromNames(names, module=None)

      Similar to ``loadTestsFromName()``, but takes a sequence of
      names rather than a single name.  The return value is a test
      suite which supports all the tests defined for each name.

   getTestCaseNames(testCaseClass)

      Return a sorted sequence of method names found within
      *testCaseClass*; this should be a subclass of ``TestCase``.

   discover(start_dir, pattern='test*.py', top_level_dir=None)

      Find and return all test modules from the specified start
      directory, recursing into subdirectories to find them. Only test
      files that match *pattern* will be loaded. (Using shell style
      pattern matching.) Only module names that are importable (i.e.
      are valid Python identifiers) will be loaded.

      All test modules must be importable from the top level of the
      project. If the start directory is not the top level directory
      then the top level directory must be specified separately.

      If importing a module fails, for example due to a syntax error,
      then this will be recorded as a single error and discovery will
      continue.

      If a test package name (directory with ``__init__.py``) matches
      the pattern then the package will be checked for a
      ``load_tests`` function. If this exists then it will be called
      with *loader*, *tests*, *pattern*.

      If load_tests exists then discovery does *not* recurse into the
      package, ``load_tests`` is responsible for loading all tests in
      the package.

      The pattern is deliberately not stored as a loader attribute so
      that packages can continue discovery themselves. *top_level_dir*
      is stored so ``load_tests`` does not need to pass this argument
      in to ``loader.discover()``.

      *start_dir* can be a dotted module name as well as a directory.

      New in version 2.7.

   The following attributes of a ``TestLoader`` can be configured
   either by subclassing or assignment on an instance:

   testMethodPrefix

      String giving the prefix of method names which will be
      interpreted as test methods.  The default value is ``'test'``.

      This affects ``getTestCaseNames()`` and all the
      ``loadTestsFrom*()`` methods.

   sortTestMethodsUsing

      Function to be used to compare method names when sorting them in
      ``getTestCaseNames()`` and all the ``loadTestsFrom*()`` methods.
      The default value is the built-in ``cmp()`` function; the
      attribute can also be set to ``None`` to disable the sort.

   suiteClass

      Callable object that constructs a test suite from a list of
      tests. No methods on the resulting object are needed.  The
      default value is the ``TestSuite`` class.

      This affects all the ``loadTestsFrom*()`` methods.

class class unittest.TestResult

   This class is used to compile information about which tests have
   succeeded and which have failed.

   A ``TestResult`` object stores the results of a set of tests.  The
   ``TestCase`` and ``TestSuite`` classes ensure that results are
   properly recorded; test authors do not need to worry about
   recording the outcome of tests.

   Testing frameworks built on top of ``unittest`` may want access to
   the ``TestResult`` object generated by running a set of tests for
   reporting purposes; a ``TestResult`` instance is returned by the
   ``TestRunner.run()`` method for this purpose.

   ``TestResult`` instances have the following attributes that will be
   of interest when inspecting the results of running a set of tests:

   errors

      A list containing 2-tuples of ``TestCase`` instances and strings
      holding formatted tracebacks. Each tuple represents a test which
      raised an unexpected exception.

      Changed in version 2.2: Contains formatted tracebacks instead of
      ``sys.exc_info()`` results.

   failures

      A list containing 2-tuples of ``TestCase`` instances and strings
      holding formatted tracebacks. Each tuple represents a test where
      a failure was explicitly signalled using the
      ``TestCase.fail*()`` or ``TestCase.assert*()`` methods.

      Changed in version 2.2: Contains formatted tracebacks instead of
      ``sys.exc_info()`` results.

   skipped

      A list containing 2-tuples of ``TestCase`` instances and strings
      holding the reason for skipping the test.

      New in version 2.7.

   expectedFailures

      A list containing 2-tuples of ``TestCase`` instances and strings
      holding formatted tracebacks.  Each tuple represents an expected
      failure of the test case.

   unexpectedSuccesses

      A list containing ``TestCase`` instances that were marked as
      expected failures, but succeeded.

   shouldStop

      Set to ``True`` when the execution of tests should stop by
      ``stop()``.

   testsRun

      The total number of tests run so far.

   buffer

      If set to true, ``sys.stdout`` and ``sys.stderr`` will be
      buffered in between ``startTest()`` and ``stopTest()`` being
      called. Collected output will only be echoed onto the real
      ``sys.stdout`` and ``sys.stderr`` if the test fails or errors.
      Any output is also attached to the failure / error message.

      New in version 2.7.

   failfast

      If set to true ``stop()`` will be called on the first failure or
      error, halting the test run.

      New in version 2.7.

   wasSuccessful()

      Return ``True`` if all tests run so far have passed, otherwise
      returns ``False``.

   stop()

      This method can be called to signal that the set of tests being
      run should be aborted by setting the ``shouldStop`` attribute to
      ``True``. ``TestRunner`` objects should respect this flag and
      return without running any additional tests.

      For example, this feature is used by the ``TextTestRunner``
      class to stop the test framework when the user signals an
      interrupt from the keyboard.  Interactive tools which provide
      ``TestRunner`` implementations can use this in a similar manner.

   The following methods of the ``TestResult`` class are used to
   maintain the internal data structures, and may be extended in
   subclasses to support additional reporting requirements.  This is
   particularly useful in building tools which support interactive
   reporting while tests are being run.

   startTest(test)

      Called when the test case *test* is about to be run.

   stopTest(test)

      Called after the test case *test* has been executed, regardless
      of the outcome.

   startTestRun(test)

      Called once before any tests are executed.

      New in version 2.7.

   stopTestRun(test)

      Called once after all tests are executed.

      New in version 2.7.

   addError(test, err)

      Called when the test case *test* raises an unexpected exception
      *err* is a tuple of the form returned by ``sys.exc_info()``:
      ``(type, value, traceback)``.

      The default implementation appends a tuple ``(test,
      formatted_err)`` to the instance's ``errors`` attribute, where
      *formatted_err* is a formatted traceback derived from *err*.

   addFailure(test, err)

      Called when the test case *test* signals a failure. *err* is a
      tuple of the form returned by ``sys.exc_info()``: ``(type,
      value, traceback)``.

      The default implementation appends a tuple ``(test,
      formatted_err)`` to the instance's ``failures`` attribute, where
      *formatted_err* is a formatted traceback derived from *err*.

   addSuccess(test)

      Called when the test case *test* succeeds.

      The default implementation does nothing.

   addSkip(test, reason)

      Called when the test case *test* is skipped.  *reason* is the
      reason the test gave for skipping.

      The default implementation appends a tuple ``(test, reason)`` to
      the instance's ``skipped`` attribute.

   addExpectedFailure(test, err)

      Called when the test case *test* fails, but was marked with the
      ``expectedFailure()`` decorator.

      The default implementation appends a tuple ``(test,
      formatted_err)`` to the instance's ``expectedFailures``
      attribute, where *formatted_err* is a formatted traceback
      derived from *err*.

   addUnexpectedSuccess(test)

      Called when the test case *test* was marked with the
      ``expectedFailure()`` decorator, but succeeded.

      The default implementation appends the test to the instance's
      ``unexpectedSuccesses`` attribute.

class class unittest.TextTestResult(stream, descriptions, verbosity)

   A concrete implementation of ``TestResult`` used by the
   ``TextTestRunner``.

   New in version 2.7: This class was previously named
   ``_TextTestResult``. The old name still exists as an alias but is
   deprecated.

unittest.defaultTestLoader

   Instance of the ``TestLoader`` class intended to be shared.  If no
   customization of the ``TestLoader`` is needed, this instance can be
   used instead of repeatedly creating new instances.

class class unittest.TextTestRunner(stream=sys.stderr, descriptions=True, verbosity=1)

   A basic test runner implementation which prints results on standard
   error.  It has a few configurable parameters, but is essentially
   very simple.  Graphical applications which run test suites should
   provide alternate implementations.

   _makeResult()

      This method returns the instance of ``TestResult`` used by
      ``run()``. It is not intended to be called directly, but can be
      overridden in subclasses to provide a custom ``TestResult``.

      ``_makeResult()`` instantiates the class or callable passed in
      the ``TextTestRunner`` constructor as the ``resultclass``
      argument. It defaults to ``TextTestResult`` if no
      ``resultclass`` is provided. The result class is instantiated
      with the following arguments:

         stream, descriptions, verbosity

unittest.main([module[, defaultTest[, argv[, testRunner[, testLoader[, exit[, verbosity[, failfast[, catchbreak[, buffer]]]]]]]]]])

   A command-line program that loads a set of tests from *module* and
   runs them; this is primarily for making test modules conveniently
   executable. The simplest use for this function is to include the
   following line at the end of a test script:

      if __name__ == '__main__':
          unittest.main()

   You can run tests with more detailed information by passing in the
   verbosity argument:

      if __name__ == '__main__':
          unittest.main(verbosity=2)

   The *argv* argument can be a list of options passed to the program,
   with the first element being the program name.  If not specified or
   ``None``, the values of ``sys.argv`` are used.

   The *testRunner* argument can either be a test runner class or an
   already created instance of it. By default ``main`` calls
   ``sys.exit()`` with an exit code indicating success or failure of
   the tests run.

   The *testLoader* argument has to be a ``TestLoader`` instance, and
   defaults to ``defaultTestLoader``.

   ``main`` supports being used from the interactive interpreter by
   passing in the argument ``exit=False``. This displays the result on
   standard output without calling ``sys.exit()``:

      >>> from unittest import main
      >>> main(module='test_module', exit=False)

   The *failfast*, *catchbreak* and *buffer* parameters have the same
   effect as the same-name command-line options.

   Calling ``main`` actually returns an instance of the
   ``TestProgram`` class. This stores the result of the tests run as
   the ``result`` attribute.

   Changed in version 2.7: The *exit*, *verbosity*, *failfast*,
   *catchbreak* and *buffer* parameters were added.


load_tests Protocol
~~~~~~~~~~~~~~~~~~~

New in version 2.7.

Modules or packages can customize how tests are loaded from them
during normal test runs or test discovery by implementing a function
called ``load_tests``.

If a test module defines ``load_tests`` it will be called by
``TestLoader.loadTestsFromModule()`` with the following arguments:

   load_tests(loader, standard_tests, None)

It should return a ``TestSuite``.

*loader* is the instance of ``TestLoader`` doing the loading.
*standard_tests* are the tests that would be loaded by default from
the module. It is common for test modules to only want to add or
remove tests from the standard set of tests. The third argument is
used when loading packages as part of test discovery.

A typical ``load_tests`` function that loads tests from a specific set
of ``TestCase`` classes may look like:

   test_cases = (TestCase1, TestCase2, TestCase3)

   def load_tests(loader, tests, pattern):
       suite = TestSuite()
       for test_class in test_cases:
           tests = loader.loadTestsFromTestCase(test_class)
           suite.addTests(tests)
       return suite

If discovery is started, either from the command line or by calling
``TestLoader.discover()``, with a pattern that matches a package name
then the package ``__init__.py`` will be checked for ``load_tests``.

Note: The default pattern is ``'test*.py'``. This matches all Python files
  that start with ``'test'`` but *won't* match any test directories.A
  pattern like ``'test*'`` will match test packages as well as
  modules.

If the package ``__init__.py`` defines ``load_tests`` then it will be
called and discovery not continued into the package. ``load_tests`` is
called with the following arguments:

   load_tests(loader, standard_tests, pattern)

This should return a ``TestSuite`` representing all the tests from the
package. (``standard_tests`` will only contain tests collected from
``__init__.py``.)

Because the pattern is passed into ``load_tests`` the package is free
to continue (and potentially modify) test discovery. A 'do nothing'
``load_tests`` function for a test package would look like:

   def load_tests(loader, standard_tests, pattern):
       # top level directory cached on loader instance
       this_dir = os.path.dirname(__file__)
       package_tests = loader.discover(start_dir=this_dir, pattern=pattern)
       standard_tests.addTests(package_tests)
       return standard_tests


Class and Module Fixtures
=========================

Class and module level fixtures are implemented in ``TestSuite``. When
the test suite encounters a test from a new class then
``tearDownClass()`` from the previous class (if there is one) is
called, followed by ``setUpClass()`` from the new class.

Similarly if a test is from a different module from the previous test
then ``tearDownModule`` from the previous module is run, followed by
``setUpModule`` from the new module.

After all the tests have run the final ``tearDownClass`` and
``tearDownModule`` are run.

Note that shared fixtures do not play well with [potential] features
like test parallelization and they break test isolation. They should
be used with care.

The default ordering of tests created by the unittest test loaders is
to group all tests from the same modules and classes together. This
will lead to ``setUpClass`` / ``setUpModule`` (etc) being called
exactly once per class and module. If you randomize the order, so that
tests from different modules and classes are adjacent to each other,
then these shared fixture functions may be called multiple times in a
single test run.

Shared fixtures are not intended to work with suites with non-standard
ordering. A ``BaseTestSuite`` still exists for frameworks that don't
want to support shared fixtures.

If there are any exceptions raised during one of the shared fixture
functions the test is reported as an error. Because there is no
corresponding test instance an ``_ErrorHolder`` object (that has the
same interface as a ``TestCase``) is created to represent the error.
If you are just using the standard unittest test runner then this
detail doesn't matter, but if you are a framework author it may be
relevant.


setUpClass and tearDownClass
----------------------------

These must be implemented as class methods:

   import unittest

   class Test(unittest.TestCase):
       @classmethod
       def setUpClass(cls):
           cls._connection = createExpensiveConnectionObject()

       @classmethod
       def tearDownClass(cls):
           cls._connection.destroy()

If you want the ``setUpClass`` and ``tearDownClass`` on base classes
called then you must call up to them yourself. The implementations in
``TestCase`` are empty.

If an exception is raised during a ``setUpClass`` then the tests in
the class are not run and the ``tearDownClass`` is not run. Skipped
classes will not have ``setUpClass`` or ``tearDownClass`` run. If the
exception is a ``SkipTest`` exception then the class will be reported
as having been skipped instead of as an error.


setUpModule and tearDownModule
------------------------------

These should be implemented as functions:

   def setUpModule():
       createConnection()

   def tearDownModule():
       closeConnection()

If an exception is raised in a ``setUpModule`` then none of the tests
in the module will be run and the ``tearDownModule`` will not be run.
If the exception is a ``SkipTest`` exception then the module will be
reported as having been skipped instead of as an error.


Signal Handling
===============

The *-c/--catch* command-line option to unittest, along with the
``catchbreak`` parameter to ``unittest.main()``, provide more friendly
handling of control-C during a test run. With catch break behavior
enabled control-C will allow the currently running test to complete,
and the test run will then end and report all the results so far. A
second control-c will raise a ``KeyboardInterrupt`` in the usual way.

The control-c handling signal handler attempts to remain compatible
with code or tests that install their own ``signal.SIGINT`` handler.
If the ``unittest`` handler is called but *isn't* the installed
``signal.SIGINT`` handler, i.e. it has been replaced by the system
under test and delegated to, then it calls the default handler. This
will normally be the expected behavior by code that replaces an
installed handler and delegates to it. For individual tests that need
``unittest`` control-c handling disabled the ``removeHandler()``
decorator can be used.

There are a few utility functions for framework authors to enable
control-c handling functionality within test frameworks.

unittest.installHandler()

   Install the control-c handler. When a ``signal.SIGINT`` is received
   (usually in response to the user pressing control-c) all registered
   results have ``stop()`` called.

   New in version 2.7.

unittest.registerResult(result)

   Register a ``TestResult`` object for control-c handling.
   Registering a result stores a weak reference to it, so it doesn't
   prevent the result from being garbage collected.

   Registering a ``TestResult`` object has no side-effects if
   control-c handling is not enabled, so test frameworks can
   unconditionally register all results they create independently of
   whether or not handling is enabled.

   New in version 2.7.

unittest.removeResult(result)

   Remove a registered result. Once a result has been removed then
   ``stop()`` will no longer be called on that result object in
   response to a control-c.

   New in version 2.7.

unittest.removeHandler(function=None)

   When called without arguments this function removes the control-c
   handler if it has been installed. This function can also be used as
   a test decorator to temporarily remove the handler whilst the test
   is being executed:

      @unittest.removeHandler
      def test_signal_handling(self):
          ...

   New in version 2.7.
