949 lines
36 KiB
ReStructuredText
949 lines
36 KiB
ReStructuredText
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:mod:`unittest` --- Unit testing framework
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==========================================
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.. module:: unittest
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:synopsis: Unit testing framework for Python.
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.. moduleauthor:: Steve Purcell <stephen_purcell@yahoo.com>
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.. sectionauthor:: Steve Purcell <stephen_purcell@yahoo.com>
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.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
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.. sectionauthor:: Raymond Hettinger <python@rcn.com>
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.. versionadded:: 2.1
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The Python unit testing framework, sometimes referred to as "PyUnit," is a
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Python language version of JUnit, by Kent Beck and Erich Gamma. JUnit is, in
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turn, a Java version of Kent's Smalltalk testing framework. Each is the de
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facto standard unit testing framework for its respective language.
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:mod:`unittest` supports test automation, sharing of setup and shutdown code for
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tests, aggregation of tests into collections, and independence of the tests from
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the reporting framework. The :mod:`unittest` module provides classes that make
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it easy to support these qualities for a set of tests.
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To achieve this, :mod:`unittest` supports some important concepts:
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test fixture
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A :dfn:`test fixture` represents the preparation needed to perform one or more
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tests, and any associate cleanup actions. This may involve, for example,
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creating temporary or proxy databases, directories, or starting a server
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process.
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test case
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A :dfn:`test case` is the smallest unit of testing. It checks for a specific
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response to a particular set of inputs. :mod:`unittest` provides a base class,
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:class:`TestCase`, which may be used to create new test cases.
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test suite
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A :dfn:`test suite` is a collection of test cases, test suites, or both. It is
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used to aggregate tests that should be executed together.
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test runner
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A :dfn:`test runner` is a component which orchestrates the execution of tests
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and provides the outcome to the user. The runner may use a graphical interface,
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a textual interface, or return a special value to indicate the results of
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executing the tests.
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The test case and test fixture concepts are supported through the
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:class:`TestCase` and :class:`FunctionTestCase` classes; the former should be
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used when creating new tests, and the latter can be used when integrating
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existing test code with a :mod:`unittest`\ -driven framework. When building test
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fixtures using :class:`TestCase`, the :meth:`setUp` and :meth:`tearDown` methods
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can be overridden to provide initialization and cleanup for the fixture. With
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:class:`FunctionTestCase`, existing functions can be passed to the constructor
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for these purposes. When the test is run, the fixture initialization is run
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first; if it succeeds, the cleanup method is run after the test has been
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executed, regardless of the outcome of the test. Each instance of the
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:class:`TestCase` will only be used to run a single test method, so a new
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fixture is created for each test.
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Test suites are implemented by the :class:`TestSuite` class. This class allows
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individual tests and test suites to be aggregated; when the suite is executed,
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all tests added directly to the suite and in "child" test suites are run.
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A test runner is an object that provides a single method, :meth:`run`, which
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accepts a :class:`TestCase` or :class:`TestSuite` object as a parameter, and
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returns a result object. The class :class:`TestResult` is provided for use as
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the result object. :mod:`unittest` provides the :class:`TextTestRunner` as an
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example test runner which reports test results on the standard error stream by
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default. Alternate runners can be implemented for other environments (such as
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graphical environments) without any need to derive from a specific class.
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.. seealso::
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Module :mod:`doctest`
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Another test-support module with a very different flavor.
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`Simple Smalltalk Testing: With Patterns <http://www.XProgramming.com/testfram.htm>`_
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Kent Beck's original paper on testing frameworks using the pattern shared by
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:mod:`unittest`.
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.. _unittest-minimal-example:
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Basic example
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-------------
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The :mod:`unittest` module provides a rich set of tools for constructing and
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running tests. This section demonstrates that a small subset of the tools
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suffice to meet the needs of most users.
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Here is a short script to test three functions from the :mod:`random` module::
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import random
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import unittest
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class TestSequenceFunctions(unittest.TestCase):
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def setUp(self):
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self.seq = range(10)
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def testshuffle(self):
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# make sure the shuffled sequence does not lose any elements
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random.shuffle(self.seq)
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self.seq.sort()
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self.assertEqual(self.seq, range(10))
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def testchoice(self):
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element = random.choice(self.seq)
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self.assert_(element in self.seq)
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def testsample(self):
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self.assertRaises(ValueError, random.sample, self.seq, 20)
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for element in random.sample(self.seq, 5):
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self.assert_(element in self.seq)
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if __name__ == '__main__':
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unittest.main()
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A testcase is created by subclassing :class:`unittest.TestCase`. The three
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individual tests are defined with methods whose names start with the letters
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``test``. This naming convention informs the test runner about which methods
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represent tests.
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The crux of each test is a call to :meth:`assertEqual` to check for an expected
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result; :meth:`assert_` to verify a condition; or :meth:`assertRaises` to verify
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that an expected exception gets raised. These methods are used instead of the
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:keyword:`assert` statement so the test runner can accumulate all test results
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and produce a report.
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When a :meth:`setUp` method is defined, the test runner will run that method
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prior to each test. Likewise, if a :meth:`tearDown` method is defined, the test
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runner will invoke that method after each test. In the example, :meth:`setUp`
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was used to create a fresh sequence for each test.
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The final block shows a simple way to run the tests. :func:`unittest.main`
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provides a command line interface to the test script. When run from the command
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line, the above script produces an output that looks like this::
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...
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----------------------------------------------------------------------
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Ran 3 tests in 0.000s
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OK
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Instead of :func:`unittest.main`, there are other ways to run the tests with a
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finer level of control, less terse output, and no requirement to be run from the
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command line. For example, the last two lines may be replaced with::
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suite = unittest.TestLoader().loadTestsFromTestCase(TestSequenceFunctions)
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unittest.TextTestRunner(verbosity=2).run(suite)
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Running the revised script from the interpreter or another script produces the
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following output::
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testchoice (__main__.TestSequenceFunctions) ... ok
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testsample (__main__.TestSequenceFunctions) ... ok
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testshuffle (__main__.TestSequenceFunctions) ... ok
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----------------------------------------------------------------------
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Ran 3 tests in 0.110s
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OK
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The above examples show the most commonly used :mod:`unittest` features which
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are sufficient to meet many everyday testing needs. The remainder of the
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documentation explores the full feature set from first principles.
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.. _organizing-tests:
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Organizing test code
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--------------------
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The basic building blocks of unit testing are :dfn:`test cases` --- single
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scenarios that must be set up and checked for correctness. In :mod:`unittest`,
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test cases are represented by instances of :mod:`unittest`'s :class:`TestCase`
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class. To make your own test cases you must write subclasses of
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:class:`TestCase`, or use :class:`FunctionTestCase`.
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An instance of a :class:`TestCase`\ -derived class is an object that can
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completely run a single test method, together with optional set-up and tidy-up
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code.
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The testing code of a :class:`TestCase` instance should be entirely self
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contained, such that it can be run either in isolation or in arbitrary
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combination with any number of other test cases.
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The simplest :class:`TestCase` subclass will simply override the :meth:`runTest`
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method in order to perform specific testing code::
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import unittest
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class DefaultWidgetSizeTestCase(unittest.TestCase):
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def runTest(self):
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widget = Widget('The widget')
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self.assertEqual(widget.size(), (50, 50), 'incorrect default size')
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Note that in order to test something, we use the one of the :meth:`assert\*` or
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:meth:`fail\*` methods provided by the :class:`TestCase` base class. If the
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test fails, an exception will be raised, and :mod:`unittest` will identify the
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test case as a :dfn:`failure`. Any other exceptions will be treated as
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:dfn:`errors`. This helps you identify where the problem is: :dfn:`failures` are
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caused by incorrect results - a 5 where you expected a 6. :dfn:`Errors` are
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caused by incorrect code - e.g., a :exc:`TypeError` caused by an incorrect
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function call.
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The way to run a test case will be described later. For now, note that to
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construct an instance of such a test case, we call its constructor without
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arguments::
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testCase = DefaultWidgetSizeTestCase()
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Now, such test cases can be numerous, and their set-up can be repetitive. In
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the above case, constructing a :class:`Widget` in each of 100 Widget test case
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subclasses would mean unsightly duplication.
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Luckily, we can factor out such set-up code by implementing a method called
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:meth:`setUp`, which the testing framework will automatically call for us when
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we run the test::
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import unittest
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class SimpleWidgetTestCase(unittest.TestCase):
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def setUp(self):
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self.widget = Widget('The widget')
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class DefaultWidgetSizeTestCase(SimpleWidgetTestCase):
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def runTest(self):
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self.failUnless(self.widget.size() == (50,50),
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'incorrect default size')
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class WidgetResizeTestCase(SimpleWidgetTestCase):
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def runTest(self):
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self.widget.resize(100,150)
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self.failUnless(self.widget.size() == (100,150),
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'wrong size after resize')
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If the :meth:`setUp` method raises an exception while the test is running, the
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framework will consider the test to have suffered an error, and the
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:meth:`runTest` method will not be executed.
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Similarly, we can provide a :meth:`tearDown` method that tidies up after the
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:meth:`runTest` method has been run::
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import unittest
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class SimpleWidgetTestCase(unittest.TestCase):
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def setUp(self):
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self.widget = Widget('The widget')
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def tearDown(self):
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self.widget.dispose()
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self.widget = None
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If :meth:`setUp` succeeded, the :meth:`tearDown` method will be run whether
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:meth:`runTest` succeeded or not.
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Such a working environment for the testing code is called a :dfn:`fixture`.
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Often, many small test cases will use the same fixture. In this case, we would
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end up subclassing :class:`SimpleWidgetTestCase` into many small one-method
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classes such as :class:`DefaultWidgetSizeTestCase`. This is time-consuming and
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discouraging, so in the same vein as JUnit, :mod:`unittest` provides a simpler
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mechanism::
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import unittest
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class WidgetTestCase(unittest.TestCase):
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def setUp(self):
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self.widget = Widget('The widget')
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def tearDown(self):
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self.widget.dispose()
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self.widget = None
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def testDefaultSize(self):
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self.failUnless(self.widget.size() == (50,50),
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'incorrect default size')
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def testResize(self):
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self.widget.resize(100,150)
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self.failUnless(self.widget.size() == (100,150),
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'wrong size after resize')
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Here we have not provided a :meth:`runTest` method, but have instead provided
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two different test methods. Class instances will now each run one of the
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:meth:`test\*` methods, with ``self.widget`` created and destroyed separately
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for each instance. When creating an instance we must specify the test method it
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is to run. We do this by passing the method name in the constructor::
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defaultSizeTestCase = WidgetTestCase('testDefaultSize')
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resizeTestCase = WidgetTestCase('testResize')
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Test case instances are grouped together according to the features they test.
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:mod:`unittest` provides a mechanism for this: the :dfn:`test suite`,
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represented by :mod:`unittest`'s :class:`TestSuite` class::
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widgetTestSuite = unittest.TestSuite()
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widgetTestSuite.addTest(WidgetTestCase('testDefaultSize'))
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widgetTestSuite.addTest(WidgetTestCase('testResize'))
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For the ease of running tests, as we will see later, it is a good idea to
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provide in each test module a callable object that returns a pre-built test
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suite::
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def suite():
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suite = unittest.TestSuite()
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suite.addTest(WidgetTestCase('testDefaultSize'))
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suite.addTest(WidgetTestCase('testResize'))
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return suite
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or even::
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def suite():
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tests = ['testDefaultSize', 'testResize']
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return unittest.TestSuite(map(WidgetTestCase, tests))
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Since it is a common pattern to create a :class:`TestCase` subclass with many
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similarly named test functions, :mod:`unittest` provides a :class:`TestLoader`
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class that can be used to automate the process of creating a test suite and
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populating it with individual tests. For example, ::
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suite = unittest.TestLoader().loadTestsFromTestCase(WidgetTestCase)
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will create a test suite that will run ``WidgetTestCase.testDefaultSize()`` and
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``WidgetTestCase.testResize``. :class:`TestLoader` uses the ``'test'`` method
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name prefix to identify test methods automatically.
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Note that the order in which the various test cases will be run is determined by
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sorting the test function names with the built-in :func:`cmp` function.
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Often it is desirable to group suites of test cases together, so as to run tests
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for the whole system at once. This is easy, since :class:`TestSuite` instances
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can be added to a :class:`TestSuite` just as :class:`TestCase` instances can be
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added to a :class:`TestSuite`::
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suite1 = module1.TheTestSuite()
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suite2 = module2.TheTestSuite()
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alltests = unittest.TestSuite([suite1, suite2])
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You can place the definitions of test cases and test suites in the same modules
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as the code they are to test (such as :file:`widget.py`), but there are several
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advantages to placing the test code in a separate module, such as
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:file:`test_widget.py`:
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* The test module can be run standalone from the command line.
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* The test code can more easily be separated from shipped code.
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* There is less temptation to change test code to fit the code it tests without
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a good reason.
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* Test code should be modified much less frequently than the code it tests.
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* Tested code can be refactored more easily.
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* Tests for modules written in C must be in separate modules anyway, so why not
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be consistent?
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* If the testing strategy changes, there is no need to change the source code.
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.. _legacy-unit-tests:
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Re-using old test code
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----------------------
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Some users will find that they have existing test code that they would like to
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run from :mod:`unittest`, without converting every old test function to a
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:class:`TestCase` subclass.
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For this reason, :mod:`unittest` provides a :class:`FunctionTestCase` class.
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This subclass of :class:`TestCase` can be used to wrap an existing test
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function. Set-up and tear-down functions can also be provided.
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Given the following test function::
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def testSomething():
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something = makeSomething()
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assert something.name is not None
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# ...
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one can create an equivalent test case instance as follows::
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testcase = unittest.FunctionTestCase(testSomething)
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If there are additional set-up and tear-down methods that should be called as
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part of the test case's operation, they can also be provided like so::
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testcase = unittest.FunctionTestCase(testSomething,
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setUp=makeSomethingDB,
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tearDown=deleteSomethingDB)
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To make migrating existing test suites easier, :mod:`unittest` supports tests
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raising :exc:`AssertionError` to indicate test failure. However, it is
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recommended that you use the explicit :meth:`TestCase.fail\*` and
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:meth:`TestCase.assert\*` methods instead, as future versions of :mod:`unittest`
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may treat :exc:`AssertionError` differently.
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.. note::
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Even though :class:`FunctionTestCase` can be used to quickly convert an existing
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test base over to a :mod:`unittest`\ -based system, this approach is not
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recommended. Taking the time to set up proper :class:`TestCase` subclasses will
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make future test refactorings infinitely easier.
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.. _unittest-contents:
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Classes and functions
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---------------------
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.. class:: TestCase([methodName])
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Instances of the :class:`TestCase` class represent the smallest testable units
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in the :mod:`unittest` universe. This class is intended to be used as a base
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class, with specific tests being implemented by concrete subclasses. This class
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implements the interface needed by the test runner to allow it to drive the
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test, and methods that the test code can use to check for and report various
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kinds of failure.
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Each instance of :class:`TestCase` will run a single test method: the method
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named *methodName*. If you remember, we had an earlier example that went
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something like this::
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def suite():
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suite = unittest.TestSuite()
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suite.addTest(WidgetTestCase('testDefaultSize'))
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suite.addTest(WidgetTestCase('testResize'))
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return suite
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Here, we create two instances of :class:`WidgetTestCase`, each of which runs a
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single test.
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*methodName* defaults to ``'runTest'``.
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.. class:: FunctionTestCase(testFunc[, setUp[, tearDown[, description]]])
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This class implements the portion of the :class:`TestCase` interface which
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allows the test runner to drive the test, but does not provide the methods which
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test code can use to check and report errors. This is used to create test cases
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using legacy test code, allowing it to be integrated into a :mod:`unittest`\
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-based test framework.
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.. class:: TestSuite([tests])
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This class represents an aggregation of individual tests cases and test suites.
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The class presents the interface needed by the test runner to allow it to be run
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as any other test case. Running a :class:`TestSuite` instance is the same as
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iterating over the suite, running each test individually.
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If *tests* is given, it must be an iterable of individual test cases or other
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test suites that will be used to build the suite initially. Additional methods
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are provided to add test cases and suites to the collection later on.
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.. class:: TestLoader()
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This class is responsible for loading tests according to various criteria and
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returning them wrapped in a :class:`TestSuite`. It can load all tests within a
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given module or :class:`TestCase` subclass.
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.. class:: TestResult()
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This class is used to compile information about which tests have succeeded and
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which have failed.
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.. data:: defaultTestLoader
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Instance of the :class:`TestLoader` class intended to be shared. If no
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customization of the :class:`TestLoader` is needed, this instance can be used
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instead of repeatedly creating new instances.
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.. class:: TextTestRunner([stream[, descriptions[, verbosity]]])
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A basic test runner implementation which prints results on standard error. It
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has a few configurable parameters, but is essentially very simple. Graphical
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applications which run test suites should provide alternate implementations.
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.. function:: main([module[, defaultTest[, argv[, testRunner[, testLoader]]]]])
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A command-line program that runs a set of tests; this is primarily for making
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test modules conveniently executable. The simplest use for this function is to
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include the following line at the end of a test script::
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if __name__ == '__main__':
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unittest.main()
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The *testRunner* argument can either be a test runner class or an already
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created instance of it.
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In some cases, the existing tests may have been written using the :mod:`doctest`
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module. If so, that module provides a :class:`DocTestSuite` class that can
|
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automatically build :class:`unittest.TestSuite` instances from the existing
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:mod:`doctest`\ -based tests.
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.. versionadded:: 2.3
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.. _testcase-objects:
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TestCase Objects
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----------------
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Each :class:`TestCase` instance represents a single test, but each concrete
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subclass may be used to define multiple tests --- the concrete class represents
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a single test fixture. The fixture is created and cleaned up for each test
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case.
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:class:`TestCase` instances provide three groups of methods: one group used to
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run the test, another used by the test implementation to check conditions and
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report failures, and some inquiry methods allowing information about the test
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itself to be gathered.
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Methods in the first group (running the test) are:
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.. method:: TestCase.setUp()
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Method called to prepare the test fixture. This is called immediately before
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calling the test method; any exception raised by this method will be considered
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an error rather than a test failure. The default implementation does nothing.
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.. method:: TestCase.tearDown()
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Method called immediately after the test method has been called and the result
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recorded. This is called even if the test method raised an exception, so the
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implementation in subclasses may need to be particularly careful about checking
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internal state. Any exception raised by this method will be considered an error
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rather than a test failure. This method will only be called if the
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:meth:`setUp` succeeds, regardless of the outcome of the test method. The
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default implementation does nothing.
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.. method:: TestCase.run([result])
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Run the test, collecting the result into the test result object passed as
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*result*. If *result* is omitted or :const:`None`, a temporary result object is
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created (by calling the :meth:`defaultTestCase` method) and used; this result
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object is not returned to :meth:`run`'s caller.
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The same effect may be had by simply calling the :class:`TestCase` instance.
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.. method:: TestCase.debug()
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Run the test without collecting the result. This allows exceptions raised by
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the test to be propagated to the caller, and can be used to support running
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tests under a debugger.
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The test code can use any of the following methods to check for and report
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failures.
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.. method:: TestCase.assert_(expr[, msg])
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TestCase.failUnless(expr[, msg])
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TestCase.assertTrue(expr[, msg])
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Signal a test failure if *expr* is false; the explanation for the error will be
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*msg* if given, otherwise it will be :const:`None`.
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.. method:: TestCase.assertEqual(first, second[, msg])
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TestCase.failUnlessEqual(first, second[, msg])
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Test that *first* and *second* are equal. If the values do not compare equal,
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the test will fail with the explanation given by *msg*, or :const:`None`. Note
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that using :meth:`failUnlessEqual` improves upon doing the comparison as the
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first parameter to :meth:`failUnless`: the default value for *msg* can be
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computed to include representations of both *first* and *second*.
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.. method:: TestCase.assertNotEqual(first, second[, msg])
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TestCase.failIfEqual(first, second[, msg])
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Test that *first* and *second* are not equal. If the values do compare equal,
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the test will fail with the explanation given by *msg*, or :const:`None`. Note
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that using :meth:`failIfEqual` improves upon doing the comparison as the first
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parameter to :meth:`failUnless` is that the default value for *msg* can be
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computed to include representations of both *first* and *second*.
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.. method:: TestCase.assertAlmostEqual(first, second[, places[, msg]])
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TestCase.failUnlessAlmostEqual(first, second[, places[, msg]])
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Test that *first* and *second* are approximately equal by computing the
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difference, rounding to the given number of decimal *places* (default 7),
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and comparing to zero.
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Note that comparing a given number of decimal places is not the same as
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comparing a given number of significant digits. If the values do not compare
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equal, the test will fail with the explanation given by *msg*, or :const:`None`.
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.. method:: TestCase.assertNotAlmostEqual(first, second[, places[, msg]])
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TestCase.failIfAlmostEqual(first, second[, places[, msg]])
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Test that *first* and *second* are not approximately equal by computing the
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difference, rounding to the given number of decimal *places* (default 7),
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and comparing to zero.
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Note that comparing a given number of decimal places is not the same as
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comparing a given number of significant digits. If the values do not compare
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equal, the test will fail with the explanation given by *msg*, or :const:`None`.
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.. method:: TestCase.assertRaises(exception[, callable, ...])
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TestCase.failUnlessRaises(exception[, callable, ...])
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Test that an exception is raised when *callable* is called with any positional
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or keyword arguments that are also passed to :meth:`assertRaises`. The test
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passes if *exception* is raised, is an error if another exception is raised, or
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fails if no exception is raised. To catch any of a group of exceptions, a tuple
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containing the exception classes may be passed as *exception*.
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.. versionchanged:: 2.7
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If *callable* is omitted or None, returns a context manager so that the code
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under test can be written inline rather than as a function::
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with self.failUnlessRaises(some_error_class):
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do_something()
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.. method:: TestCase.failIf(expr[, msg])
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TestCase.assertFalse(expr[, msg])
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The inverse of the :meth:`failUnless` method is the :meth:`failIf` method. This
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signals a test failure if *expr* is true, with *msg* or :const:`None` for the
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error message.
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.. method:: TestCase.fail([msg])
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Signals a test failure unconditionally, with *msg* or :const:`None` for the
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error message.
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.. attribute:: TestCase.failureException
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This class attribute gives the exception raised by the :meth:`test` method. If
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a test framework needs to use a specialized exception, possibly to carry
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additional information, it must subclass this exception in order to "play fair"
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with the framework. The initial value of this attribute is
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:exc:`AssertionError`.
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Testing frameworks can use the following methods to collect information on the
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test:
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.. method:: TestCase.countTestCases()
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Return the number of tests represented by this test object. For
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:class:`TestCase` instances, this will always be ``1``.
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.. method:: TestCase.defaultTestResult()
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Return an instance of the test result class that should be used for this test
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case class (if no other result instance is provided to the :meth:`run` method).
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For :class:`TestCase` instances, this will always be an instance of
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:class:`TestResult`; subclasses of :class:`TestCase` should override this as
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necessary.
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.. method:: TestCase.id()
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Return a string identifying the specific test case. This is usually the full
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name of the test method, including the module and class name.
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.. method:: TestCase.shortDescription()
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Returns a one-line description of the test, or :const:`None` if no description
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has been provided. The default implementation of this method returns the first
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line of the test method's docstring, if available, or :const:`None`.
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.. _testsuite-objects:
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TestSuite Objects
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-----------------
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:class:`TestSuite` objects behave much like :class:`TestCase` objects, except
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they do not actually implement a test. Instead, they are used to aggregate
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tests into groups of tests that should be run together. Some additional methods
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are available to add tests to :class:`TestSuite` instances:
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.. method:: TestSuite.addTest(test)
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Add a :class:`TestCase` or :class:`TestSuite` to the suite.
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.. method:: TestSuite.addTests(tests)
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Add all the tests from an iterable of :class:`TestCase` and :class:`TestSuite`
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instances to this test suite.
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This is equivalent to iterating over *tests*, calling :meth:`addTest` for each
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element.
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:class:`TestSuite` shares the following methods with :class:`TestCase`:
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.. method:: TestSuite.run(result)
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Run the tests associated with this suite, collecting the result into the test
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result object passed as *result*. Note that unlike :meth:`TestCase.run`,
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:meth:`TestSuite.run` requires the result object to be passed in.
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.. method:: TestSuite.debug()
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Run the tests associated with this suite without collecting the result. This
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allows exceptions raised by the test to be propagated to the caller and can be
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used to support running tests under a debugger.
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.. method:: TestSuite.countTestCases()
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Return the number of tests represented by this test object, including all
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individual tests and sub-suites.
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In the typical usage of a :class:`TestSuite` object, the :meth:`run` method is
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invoked by a :class:`TestRunner` rather than by the end-user test harness.
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.. _testresult-objects:
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TestResult Objects
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------------------
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A :class:`TestResult` object stores the results of a set of tests. The
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:class:`TestCase` and :class:`TestSuite` classes ensure that results are
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properly recorded; test authors do not need to worry about recording the outcome
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of tests.
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Testing frameworks built on top of :mod:`unittest` may want access to the
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:class:`TestResult` object generated by running a set of tests for reporting
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purposes; a :class:`TestResult` instance is returned by the
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:meth:`TestRunner.run` method for this purpose.
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:class:`TestResult` instances have the following attributes that will be of
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interest when inspecting the results of running a set of tests:
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.. attribute:: TestResult.errors
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A list containing 2-tuples of :class:`TestCase` instances and strings holding
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formatted tracebacks. Each tuple represents a test which raised an unexpected
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exception.
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.. versionchanged:: 2.2
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Contains formatted tracebacks instead of :func:`sys.exc_info` results.
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.. attribute:: TestResult.failures
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A list containing 2-tuples of :class:`TestCase` instances and strings holding
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formatted tracebacks. Each tuple represents a test where a failure was
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explicitly signalled using the :meth:`TestCase.fail\*` or
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:meth:`TestCase.assert\*` methods.
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.. versionchanged:: 2.2
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Contains formatted tracebacks instead of :func:`sys.exc_info` results.
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.. attribute:: TestResult.testsRun
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The total number of tests run so far.
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.. method:: TestResult.wasSuccessful()
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Returns :const:`True` if all tests run so far have passed, otherwise returns
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:const:`False`.
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.. method:: TestResult.stop()
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This method can be called to signal that the set of tests being run should be
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aborted by setting the :class:`TestResult`'s ``shouldStop`` attribute to
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:const:`True`. :class:`TestRunner` objects should respect this flag and return
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without running any additional tests.
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For example, this feature is used by the :class:`TextTestRunner` class to stop
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the test framework when the user signals an interrupt from the keyboard.
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Interactive tools which provide :class:`TestRunner` implementations can use this
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in a similar manner.
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The following methods of the :class:`TestResult` class are used to maintain the
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internal data structures, and may be extended in subclasses to support
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additional reporting requirements. This is particularly useful in building
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tools which support interactive reporting while tests are being run.
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.. method:: TestResult.startTest(test)
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Called when the test case *test* is about to be run.
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The default implementation simply increments the instance's ``testsRun``
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counter.
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.. method:: TestResult.stopTest(test)
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Called after the test case *test* has been executed, regardless of the outcome.
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The default implementation does nothing.
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.. method:: TestResult.addError(test, err)
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Called when the test case *test* raises an unexpected exception *err* is a tuple
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of the form returned by :func:`sys.exc_info`: ``(type, value, traceback)``.
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The default implementation appends a tuple ``(test, formatted_err)`` to the
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instance's ``errors`` attribute, where *formatted_err* is a formatted
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traceback derived from *err*.
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.. method:: TestResult.addFailure(test, err)
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Called when the test case *test* signals a failure. *err* is a tuple of the form
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returned by :func:`sys.exc_info`: ``(type, value, traceback)``.
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The default implementation appends a tuple ``(test, formatted_err)`` to the
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instance's ``failures`` attribute, where *formatted_err* is a formatted
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traceback derived from *err*.
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.. method:: TestResult.addSuccess(test)
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Called when the test case *test* succeeds.
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The default implementation does nothing.
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.. _testloader-objects:
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TestLoader Objects
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------------------
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The :class:`TestLoader` class is used to create test suites from classes and
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modules. Normally, there is no need to create an instance of this class; the
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:mod:`unittest` module provides an instance that can be shared as
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``unittest.defaultTestLoader``. Using a subclass or instance, however, allows
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customization of some configurable properties.
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:class:`TestLoader` objects have the following methods:
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.. method:: TestLoader.loadTestsFromTestCase(testCaseClass)
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Return a suite of all tests cases contained in the :class:`TestCase`\ -derived
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:class:`testCaseClass`.
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.. method:: TestLoader.loadTestsFromModule(module)
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Return a suite of all tests cases contained in the given module. This method
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searches *module* for classes derived from :class:`TestCase` and creates an
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instance of the class for each test method defined for the class.
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.. warning::
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While using a hierarchy of :class:`TestCase`\ -derived classes can be convenient
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in sharing fixtures and helper functions, defining test methods on base classes
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that are not intended to be instantiated directly does not play well with this
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method. Doing so, however, can be useful when the fixtures are different and
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defined in subclasses.
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.. method:: TestLoader.loadTestsFromName(name[, module])
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Return a suite of all tests cases given a string specifier.
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The specifier *name* is a "dotted name" that may resolve either to a module, a
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test case class, a test method within a test case class, a :class:`TestSuite`
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instance, or a callable object which returns a :class:`TestCase` or
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:class:`TestSuite` instance. These checks are applied in the order listed here;
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that is, a method on a possible test case class will be picked up as "a test
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method within a test case class", rather than "a callable object".
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For example, if you have a module :mod:`SampleTests` containing a
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:class:`TestCase`\ -derived class :class:`SampleTestCase` with three test
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methods (:meth:`test_one`, :meth:`test_two`, and :meth:`test_three`), the
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specifier ``'SampleTests.SampleTestCase'`` would cause this method to return a
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suite which will run all three test methods. Using the specifier
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``'SampleTests.SampleTestCase.test_two'`` would cause it to return a test suite
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which will run only the :meth:`test_two` test method. The specifier can refer
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to modules and packages which have not been imported; they will be imported as a
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side-effect.
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The method optionally resolves *name* relative to the given *module*.
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.. method:: TestLoader.loadTestsFromNames(names[, module])
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Similar to :meth:`loadTestsFromName`, but takes a sequence of names rather than
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a single name. The return value is a test suite which supports all the tests
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defined for each name.
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.. method:: TestLoader.getTestCaseNames(testCaseClass)
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Return a sorted sequence of method names found within *testCaseClass*; this
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should be a subclass of :class:`TestCase`.
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The following attributes of a :class:`TestLoader` can be configured either by
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subclassing or assignment on an instance:
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.. attribute:: TestLoader.testMethodPrefix
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String giving the prefix of method names which will be interpreted as test
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methods. The default value is ``'test'``.
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This affects :meth:`getTestCaseNames` and all the :meth:`loadTestsFrom\*`
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methods.
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.. attribute:: TestLoader.sortTestMethodsUsing
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Function to be used to compare method names when sorting them in
|
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:meth:`getTestCaseNames` and all the :meth:`loadTestsFrom\*` methods. The
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default value is the built-in :func:`cmp` function; the attribute can also be
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set to :const:`None` to disable the sort.
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.. attribute:: TestLoader.suiteClass
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Callable object that constructs a test suite from a list of tests. No methods on
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the resulting object are needed. The default value is the :class:`TestSuite`
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class.
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This affects all the :meth:`loadTestsFrom\*` methods.
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