testtools: Update to latest upstream snapshot.

[nivanova/samba-autobuild/.git] / lib / testtools / doc / overview.rst

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+======================================
+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. testtools
+also ports recent unittest changes all the way back to Python 2.4.
+
+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(TestSillySquare, 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?
+==================
+
+Better assertion methods
+------------------------
+
+The standard assertion methods that come with unittest aren't as helpful as
+they could be, and there aren't quite enough of them.  testtools adds
+``assertIn``, ``assertIs``, ``assertIsInstance`` and their negatives.
+
+
+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 2.4, 2.5, 2.6, 2.7 and 3.1.