8 This document provides overview of the features provided by testtools. Refer
9 to the API docs (i.e. docstrings) for full details on a particular feature.
11 Extensions to TestCase
12 ----------------------
14 Controlling test execution
15 ~~~~~~~~~~~~~~~~~~~~~~~~~~
17 Testtools supports two ways to control how tests are executed. The simplest
18 is to add a new exception to self.exception_handlers::
20 >>> self.exception_handlers.insert(-1, (ExceptionClass, handler)).
22 Having done this, if any of setUp, tearDown, or the test method raise
23 ExceptionClass, handler will be called with the test case, test result and the
26 Secondly, by overriding __init__ to pass in runTest=RunTestFactory the whole
27 execution of the test can be altered. The default is testtools.runtest.RunTest
28 and calls case._run_setup, case._run_test_method and finally
29 case._run_teardown. Other methods to control what RunTest is used may be
36 addCleanup is a robust way to arrange for a cleanup function to be called
37 before tearDown. This is a powerful and simple alternative to putting cleanup
38 logic in a try/finally block or tearDown method. e.g.::
42 self.addCleanup(foo.unlock)
46 TestCase.addOnException
47 ~~~~~~~~~~~~~~~~~~~~~~~
49 addOnException adds an exception handler that will be called from the test
50 framework when it detects an exception from your test code. The handler is
51 given the exc_info for the exception, and can use this opportunity to attach
52 more data (via the addDetails API) and potentially other uses.
58 ``skip`` is a simple way to have a test stop running and be reported as a
59 skipped test, rather than a success/error/failure. This is an alternative to
60 convoluted logic during test loading, permitting later and more localized
61 decisions about the appropriateness of running a test. Many reasons exist to
62 skip a test - for instance when a dependency is missing, or if the test is
63 expensive and should not be run while on laptop battery power, or if the test
64 is testing an incomplete feature (this is sometimes called a TODO). Using this
65 feature when running your test suite with a TestResult object that is missing
66 the ``addSkip`` method will result in the ``addError`` method being invoked
73 testtools adds several assertion methods:
86 TestCase.assertRaises returns the caught exception. This is useful for
87 asserting more things about the exception than just the type::
89 error = self.assertRaises(UnauthorisedError, thing.frobnicate)
90 self.assertEqual('bob', error.username)
91 self.assertEqual('User bob cannot frobnicate', str(error))
97 assertThat is a clean way to write complex assertions without tying them to
98 the TestCase inheritance hierarchy (and thus making them easier to reuse).
100 assertThat takes an object to be matched, and a matcher, and fails if the
101 matcher does not match the matchee.
103 See pydoc testtools.Matcher for the protocol that matchers need to implement.
105 testtools includes some matchers in testtools.matchers.
106 python -c 'import testtools.matchers; print testtools.matchers.__all__' will
109 An example using the DocTestMatches matcher which uses doctests example
113 self.assertThat([1,2,3,4], DocTestMatches('[1, 2, 3, 4]'))
119 testtools.TestCase implements creation methods called ``getUniqueString`` and
120 ``getUniqueInteger``. See pages 419-423 of *xUnit Test Patterns* by Meszaros
121 for a detailed discussion of creation methods.
127 ``testtools.clone_test_with_new_id`` is a function to copy a test case
128 instance to one with a new name. This is helpful for implementing test
132 Extensions to TestResult
133 ------------------------
138 This method is called on result objects when a test skips. The
139 ``testtools.TestResult`` class records skips in its ``skip_reasons`` instance
140 dict. The can be reported on in much the same way as succesful tests.
146 This method controls the time used by a TestResult, permitting accurate
147 timing of test results gathered on different machines or in different threads.
148 See pydoc testtools.TestResult.time for more details.
151 ThreadsafeForwardingResult
152 ~~~~~~~~~~~~~~~~~~~~~~~~~~
154 A TestResult which forwards activity to another test result, but synchronises
155 on a semaphore to ensure that all the activity for a single test arrives in a
156 batch. This allows simple TestResults which do not expect concurrent test
157 reporting to be fed the activity from multiple test threads, or processes.
159 Note that when you provide multiple errors for a single test, the target sees
160 each error as a distinct complete test.
166 A TestResult that provides a text UI very similar to the Python standard
167 library UI. Key differences are that its supports the extended outcomes and
168 details API, and is completely encapsulated into the result object, permitting
169 it to be used without a 'TestRunner' object. Not all the Python 2.7 outcomes
170 are displayed (yet). It is also a 'quiet' result with no dots or verbose mode.
171 These limitations will be corrected soon.
177 In testtools.testresult.doubles there are three test doubles that testtools
178 uses for its own testing: Python26TestResult, Python27TestResult,
179 ExtendedTestResult. These TestResult objects implement a single variation of
180 the TestResult API each, and log activity to a list self._events. These are
181 made available for the convenience of people writing their own extensions.
184 startTestRun and stopTestRun
185 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
187 Python 2.7 added hooks 'startTestRun' and 'stopTestRun' which are called
188 before and after the entire test run. 'stopTestRun' is particularly useful for
189 test results that wish to produce summary output.
191 testtools.TestResult provides empty startTestRun and stopTestRun methods, and
192 the default testtools runner will call these methods appropriately.
195 Extensions to TestSuite
196 -----------------------
201 A TestSuite for parallel testing. This is used in conjuction with a helper that
202 runs a single suite in some parallel fashion (for instance, forking, handing
203 off to a subprocess, to a compute cloud, or simple threads).
204 ConcurrentTestSuite uses the helper to get a number of separate runnable
205 objects with a run(result), runs them all in threads using the
206 ThreadsafeForwardingResult to coalesce their activity.
212 Testtools provides a convenient way to run a test suite using the testtools
213 result object: python -m testtools.run testspec [testspec...].