# testtools: tasteful testing for Python

testtools is a set of extensions to the Python standard library’s unit testing framework. These extensions have been derived from many years of experience with unit testing in Python and come from many different sources.

What better way to start than with a contrived code snippet?:

    from testtools import TestCase
    from testtools.content import Content
    from testtools.content_type import UTF8_TEXT
    from testtools.matchers import Equals

    from myproject import SillySquareServer

    class TestSillySquareServer(TestCase):

        def setUp(self):
            super(TestSillySquareServer, self).setUp()
            self.server = self.useFixture(SillySquareServer())
            self.addCleanup(self.attach_log_file)

        def attach_log_file(self):
            self.addDetail(
                'log-file',
                Content(UTF8_TEXT,
                        lambda: open(self.server.logfile, 'r').readlines()))

        def test_server_is_cool(self):
            self.assertThat(self.server.temperature, Equals("cool"))

        def test_square(self):
            self.assertThat(self.server.silly_square_of(7), Equals(49))

## Why use testtools?

### Matchers: better than assertion methods

Of course, in any serious project you want to be able to have assertions that are specific to that project and the particular problem that it is addressing. Rather than forcing you to define your own assertion methods and maintain your own inheritance hierarchy of `TestCase` classes, testtools lets you write your own “matchers”, custom predicates that can be plugged into a unit test:

    def test_response_has_bold(self):
       # The response has bold text.
       response = self.server.getResponse()
       self.assertThat(response, HTMLContains(Tag('bold', 'b')))

### More debugging info, when you need it

testtools makes it easy to add arbitrary data to your test result. If you want to know what’s in a log file when a test fails, or what the load was on the computer when a test started, or what files were open, you can add that information with `TestCase.addDetail`, and it will appear in the test results if that test fails.

### Extend unittest, but stay compatible and re-usable

testtools goes to great lengths to allow serious test authors and test framework authors to do whatever they like with their tests and their extensions while staying compatible with the standard library’s unittest.

testtools has completely parametrized how exceptions raised in tests are mapped to `TestResult` methods and how tests are actually executed (ever wanted `tearDown` to be called regardless of whether `setUp` succeeds?)

It also provides many simple but handy utilities, like the ability to clone a test, a `MultiTestResult` object that lets many result objects get the results from one test suite, adapters to bring legacy `TestResult` objects into our new golden age.

### Cross-Python compatibility

testtools gives you the very latest in unit testing technology in a way that will work with Python 3.10+ and PyPy3.

If you wish to use testtools with Python 2.4 or 2.5, then please use testtools 0.9.15.

If you wish to use testtools with Python 2.6 or 3.2, then please use testtools 1.9.0.

If you wish to use testtools with Python 3.3 or 3.4, then please use testtools 2.3.0.

If you wish to use testtools with Python 2.7 or 3.5, then please use testtools 2.4.0.