gocept.testing

This package collects various helpers for writing tests.

Contents

• assertEllipsis
• assertStartsWith, assertEndsWith
• assertNothingRaised
• mock patch context
• assertCalledWith
• Mocking properties
• Attribute patch context
• Method call patch context
• Dict patching context manager
• Temporary directory
• Comparing mtimes
• Development

assertEllipsis

An assertion which is very helpful when using Testbrowser with unittest.TestCase (instead of doctest).

Some examples:

class MyTest(unittest.TestCase, gocept.testing.assertion.Ellipsis):
# [...]


self.assertEllipsis('...bar...', 'foo bar qux')
# -> nothing happens

self.assertEllipsis('foo', 'bar')
# -> AssertionError: Differences (ndiff with -expected +actual):
     - foo
     + bar

self.assertNotEllipsis('foo', 'foo')
# -> AssertionError: "Value unexpectedly matches expression 'foo'."

To use, inherit from gocept.testing.assertion.Ellipsis in addition to unittest.TestCase.

assertStartsWith, assertEndsWith

class MyTest(unittest.TestCase, gocept.testing.assertion.String):

    def test_something(self):
        self.assertStartsWith('foo', 'foobar') # --> pass
        self.assertEndsWith('bar', 'foobar') # --> pass
        self.assertStartsWith('qux', 'foobar') # --> fail
        self.assertEndsWith('qux', 'foobar') # --> fail

assertNothingRaised

The opposite of assertRaises(), this is an assertion that makes some tests more readable. As assertRaises(), it can be used as as context manager, too:

class MyTest(unittest.TestCase, gocept.testing.assertion.Exceptions):
# [...]

self.assertNothingRaised(do_something, 1, 2, 3)

with self.assertNothingRaised():
    do_something(1, 2, 3)

mock patch context

gocept.testing.mock.Patches collects mock patches that are valid for the whole TestCase, and resets them all in one go in tearDown (this is pending inclusion upstream as mock.patcher(), see issue 30):

class MyTest(unittest.TestCase):

    def setUp(self):
        self.patches = gocept.testing.mock.Patches()

    def tearDown(self):
        self.patches.reset()

    def test_something(self):
        compile = self.patches.add('re.compile')

It offers three methods:

add:	wraps mock.patch()
add_object:	wraps mock.patch.object
add_dict:	wraps mock.patch.dict

Note that gocept.testing does not declare a dependency on mock to be as lightweight as possible, so clients need to do that themselves.

If you want to save typing, you can mix gocept.testing.mock.PatchHelper into your TestCase, it defines a setUp method that instantiates Patches and a tearDown that calls reset() on it.

assertCalledWith

This is syntactic sugar around mock.assert_called_with, so you can write:

class MyTest(unittest.TestCase, gocept.testing.mock.Assertions):

    def test_something(self):
        dummy = mock.Mock()
        dummy(True)
        self.assertCalledWith(dummy, True)

instead of:

dummy.assert_called_with(True)

Mocking properties

gocept.testing.mock.Property is syntactic sugar directly lifted from the mock documentation that allows you to patch properties like this:

class Dummy(object):

    @property
    def foo(self):
        return False


with mock.patch('Dummy.foo', gocept.testing.mock.Property()) as foo:
    foo.return_value = 'something else'

Attribute patch context

This has nothing to do with mocks, it's a convenience helper for setting and automatically resetting attributes of objects:

class MyTest(unittest.TestCase):

    def setUp(self):
        self.patches = gocept.testing.patch.Patches()
        self.subject = MyClass()

    def tearDown(self):
        self.patches.reset()

    def test_something(self):
        self.assertEqual('one', self.subject.foo)
        self.patches.set(self.subject, 'foo', 'two')
        self.assertEqual('two', self.subject.foo)

Method call patch context

This allows to call a method and reset it later on automatically. At the moment, only methods that take a single parameter are supported, by passing in both the old value (to which it should be reset) and the new value:

class MyTest(unittest.TestCase):

    def setUp(self):
        self.patches = gocept.testing.patch.Patches()

    def tearDown(self):
        self.patches.reset()

    def test_something(self):
        self.patches.call(
            zope.component.hooks, 'setSite',
            zope.component.hooks.getSite(), new_site)

Dict patching context manager

gocept.testing.patch.Dict is a context manager allowing to change values in a dict. It restores the original dict at exit. E. g. it can be used to temporarily change values in os.environ:

>>> with gocept.testing.patch.Dict(os.environ, foo='bar', qwe='asdf'):
        print os.environ.get('foo')
bar
>>> print os.environ.get('foo')
None

Temporary directory

gocept.testing.fixture.TempDir encapsulates the common pattern to create a temporary directory and delete it after the test has run. The name of the directory is avaliable as self.tmpdir. Note that since unittest.TestCase does not call super, you need to mix in TempDir first:

class MyTest(gocept.testing.fixture.TempDir, unittest.TestCase):

    def test_something(self):
        self.assertTrue(os.path.isdir(self.tmpdir))

Comparing mtimes

gocept.testing.mtime.Newer checks that generated files are at least as new as their source counterparts (similar like make works):

class MyTest(gocept.testing.mtime.Newer, unittest.TestCase):

    source_ext = '.js'
    target_ext = '.min.js'
    message = 'run jsmin to correct this'

    def test_minified_js_files_are_younger_than_non_minified_ones(self):
        self.check_files(pkg_resources.resource_filename(
            'my.package', 'resources/js'))

Development

The git repository of the source code as well as the issue tracker are available at https://github.com/minddistrict/gocept.testing.