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Diffstat (limited to 'Doc/library/unittest.rst')
| -rw-r--r-- | Doc/library/unittest.rst | 110 |
1 files changed, 109 insertions, 1 deletions
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst index 0c00a26..66e427a 100644 --- a/Doc/library/unittest.rst +++ b/Doc/library/unittest.rst @@ -563,6 +563,68 @@ Skipped tests will not have :meth:`setUp` or :meth:`tearDown` run around them. Skipped classes will not have :meth:`setUpClass` or :meth:`tearDownClass` run. +.. _subtests: + +Distinguishing test iterations using subtests +--------------------------------------------- + +.. versionadded:: 3.4 + +When some of your tests differ only by a some very small differences, for +instance some parameters, unittest allows you to distinguish them inside +the body of a test method using the :meth:`~TestCase.subTest` context manager. + +For example, the following test:: + + class NumbersTest(unittest.TestCase): + + def test_even(self): + """ + Test that numbers between 0 and 5 are all even. + """ + for i in range(0, 6): + with self.subTest(i=i): + self.assertEqual(i % 2, 0) + +will produce the following output:: + + ====================================================================== + FAIL: test_even (__main__.NumbersTest) (i=1) + ---------------------------------------------------------------------- + Traceback (most recent call last): + File "subtests.py", line 32, in test_even + self.assertEqual(i % 2, 0) + AssertionError: 1 != 0 + + ====================================================================== + FAIL: test_even (__main__.NumbersTest) (i=3) + ---------------------------------------------------------------------- + Traceback (most recent call last): + File "subtests.py", line 32, in test_even + self.assertEqual(i % 2, 0) + AssertionError: 1 != 0 + + ====================================================================== + FAIL: test_even (__main__.NumbersTest) (i=5) + ---------------------------------------------------------------------- + Traceback (most recent call last): + File "subtests.py", line 32, in test_even + self.assertEqual(i % 2, 0) + AssertionError: 1 != 0 + +Without using a subtest, execution would stop after the first failure, +and the error would be less easy to diagnose because the value of ``i`` +wouldn't be displayed:: + + ====================================================================== + FAIL: test_even (__main__.NumbersTest) + ---------------------------------------------------------------------- + Traceback (most recent call last): + File "subtests.py", line 32, in test_even + self.assertEqual(i % 2, 0) + AssertionError: 1 != 0 + + .. _unittest-contents: Classes and functions @@ -676,6 +738,21 @@ Test cases .. versionadded:: 3.1 + .. method:: subTest(msg=None, **params) + + Return a context manager which executes the enclosed code block as a + subtest. *msg* and *params* are optional, arbitrary values which are + displayed whenever a subtest fails, allowing you to identify them + clearly. + + A test case can contain any number of subtest declarations, and + they can be arbitrarily nested. + + See :ref:`subtests` for more information. + + .. versionadded:: 3.4 + + .. method:: debug() Run the test without collecting the result. This allows exceptions raised @@ -1500,7 +1577,9 @@ Loading and running tests 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. + will be recorded as a single error and discovery will continue. If the + import failure is due to :exc:`SkipTest` being raised, it will be recorded + as a skip instead of an error. If a test package name (directory with :file:`__init__.py`) matches the pattern then the package will be checked for a ``load_tests`` @@ -1519,6 +1598,15 @@ Loading and running tests .. versionadded:: 3.2 + .. versionchanged:: 3.4 + Modules that raise :exc:`SkipTest` on import are recorded as skips, + not errors. + + .. versionchanged:: 3.4 + Paths are sorted before being imported to ensure execution order for a + given test suite is the same even if the underlying file system's ordering + is not dependent on file name like in ext3/4. + The following attributes of a :class:`TestLoader` can be configured either by subclassing or assignment on an instance: @@ -1729,6 +1817,22 @@ Loading and running tests :attr:`unexpectedSuccesses` attribute. + .. method:: addSubTest(test, subtest, outcome) + + Called when a subtest finishes. *test* is the test case + corresponding to the test method. *subtest* is a custom + :class:`TestCase` instance describing the subtest. + + If *outcome* is :const:`None`, the subtest succeeded. Otherwise, + it failed with an exception where *outcome* is a tuple of the form + returned by :func:`sys.exc_info`: ``(type, value, traceback)``. + + The default implementation does nothing when the outcome is a + success, and records subtest failures as normal failures. + + .. versionadded:: 3.4 + + .. class:: TextTestResult(stream, descriptions, verbosity) A concrete implementation of :class:`TestResult` used by the @@ -1838,6 +1942,10 @@ Loading and running tests The *verbosity*, *failfast*, *catchbreak*, *buffer* and *warnings* parameters were added. + .. versionchanged:: 3.4 + The *defaultTest* parameter was changed to also accept an iterable of + test names. + load_tests Protocol ################### |