Code Coverage
=============

If the --coverage option is used, test coverage reports will be generated.  The
directory name given as the parameter will be used to hold the reports.


    >>> import os.path, sys
    >>> directory_with_tests = os.path.join(this_directory, 'testrunner-ex')
    >>> defaults = [
    ...     '--path', directory_with_tests,
    ...     '--tests-pattern', '^sampletestsf?$',
    ...     ]

    >>> sys.argv = 'test --coverage=coverage_dir'.split()

    >>> from zope.testing import testrunner
    >>> testrunner.run_internal(defaults)
    Running samplelayers.Layer1 tests:
      Set up samplelayers.Layer1 in 0.000 seconds.
      Ran 9 tests with 0 failures and 0 errors in 0.000 seconds.
    Running samplelayers.Layer11 tests:
      Set up samplelayers.Layer11 in 0.000 seconds.
      Ran 34 tests with 0 failures and 0 errors in 0.125 seconds.
    Running samplelayers.Layer111 tests:
      Set up samplelayers.Layerx in 0.000 seconds.
      Set up samplelayers.Layer111 in 0.000 seconds.
      Ran 34 tests with 0 failures and 0 errors in 0.125 seconds.
    Running samplelayers.Layer112 tests:
      Tear down samplelayers.Layer111 in 0.000 seconds.
      Set up samplelayers.Layer112 in 0.000 seconds.
      Ran 34 tests with 0 failures and 0 errors in 0.125 seconds.
    Running samplelayers.Layer12 tests:
      Tear down samplelayers.Layer112 in 0.000 seconds.
      Tear down samplelayers.Layerx in 0.000 seconds.
      Tear down samplelayers.Layer11 in 0.000 seconds.
      Set up samplelayers.Layer12 in 0.000 seconds.
      Ran 34 tests with 0 failures and 0 errors in 0.140 seconds.
    Running samplelayers.Layer121 tests:
      Set up samplelayers.Layer121 in 0.000 seconds.
      Ran 34 tests with 0 failures and 0 errors in 0.125 seconds.
    Running samplelayers.Layer122 tests:
      Tear down samplelayers.Layer121 in 0.000 seconds.
      Set up samplelayers.Layer122 in 0.000 seconds.
      Ran 34 tests with 0 failures and 0 errors in 0.125 seconds.
    Running zope.testing.testrunner.layer.UnitTests tests:
      Tear down samplelayers.Layer122 in 0.000 seconds.
      Tear down samplelayers.Layer12 in 0.000 seconds.
      Tear down samplelayers.Layer1 in 0.000 seconds.
      Set up zope.testing.testrunner.layer.UnitTests in 0.000 seconds.
      Ran 192 tests with 0 failures and 0 errors in 0.687 seconds.
    Tearing down left over layers:
      Tear down zope.testing.testrunner.layer.UnitTests in 0.000 seconds.
    lines   cov%   module   (path)
    ...
       48   100%   sampletests.test1   (testrunner-ex/sampletests/test1.py)
       74   100%   sampletests.test11   (testrunner-ex/sampletests/test11.py)
       74   100%   sampletests.test111   (testrunner-ex/sampletests/test111.py)
       76   100%   sampletests.test112   (testrunner-ex/sampletests/test112.py)
       74   100%   sampletests.test12   (testrunner-ex/sampletests/test12.py)
       74   100%   sampletests.test121   (testrunner-ex/sampletests/test121.py)
       74   100%   sampletests.test122   (testrunner-ex/sampletests/test122.py)
       48   100%   sampletests.test_one   (testrunner-ex/sampletests/test_one.py)
      112    95%   sampletestsf   (testrunner-ex/sampletestsf.py)
    Total: 405 tests, 0 failures, 0 errors in 0.630 seconds.
    False

The directory specified with the --coverage option will have been created and
will hold the coverage reports.

    >>> os.path.exists('coverage_dir')
    True
    >>> os.listdir('coverage_dir')
    [...]

(We should clean up after ourselves.)

    >>> import shutil
    >>> shutil.rmtree('coverage_dir')


Ignoring Tests
--------------

The ``trace`` module supports ignoring directories and modules based the test
selection. Only directories selected for testing should report coverage. The
test runner provides a custom implementation of the relevant API.

The ``TestIgnore`` class, the class managing the ignoring, is initialized by
passing the command line options. It uses the options to determine the
directories that should be covered.

  >>> class FauxOptions(object):
  ...   package = None
  ...   test_path = [('/myproject/src/blah/foo', ''),
  ...                ('/myproject/src/blah/bar', '')]
  >>> from zope.testing.testrunner import coverage
  >>> from zope.testing.testrunner.find import test_dirs
  >>> ignore = coverage.TestIgnore(test_dirs(FauxOptions(), {}))
  >>> ignore._test_dirs
  ['/myproject/src/blah/foo/', '/myproject/src/blah/bar/']

We can now ask whether a particular module should be ignored:

  >>> ignore.names('/myproject/src/blah/foo/baz.py', 'baz')
  False
  >>> ignore.names('/myproject/src/blah/bar/mine.py', 'mine')
  False
  >>> ignore.names('/myproject/src/blah/foo/__init__.py', 'foo')
  False
  >>> ignore.names('/myproject/src/blah/hello.py', 'hello')
  True

When running the test runner, modules are sometimes created from text
strings. Those should *always* be ignored:

  >>> ignore.names('/myproject/src/blah/hello.txt', '<string>')
  True

To make this check fast, the class implements a cache. In an early
implementation, the result was cached by the module name, which was a problem,
since a lot of modules carry the same name (not the Python dotted name
here!). So just because a module has the same name in an ignored and tested
directory, does not mean it is always ignored:

  >>> ignore.names('/myproject/src/blah/module.py', 'module')
  True
  >>> ignore.names('/myproject/src/blah/foo/module.py', 'module')
  False