http://git-wip-us.apache.org/repos/asf/incubator-atlas/blob/c219798b/src/test/mock/docs/examples.txt ---------------------------------------------------------------------- diff --git a/src/test/mock/docs/examples.txt b/src/test/mock/docs/examples.txt deleted file mode 100644 index ecb994b..0000000 --- a/src/test/mock/docs/examples.txt +++ /dev/null @@ -1,1063 +0,0 @@ -.. _further-examples: - -================== - Further Examples -================== - -.. currentmodule:: mock - -.. testsetup:: - - from datetime import date - - BackendProvider = Mock() - sys.modules['mymodule'] = mymodule = Mock(name='mymodule') - - def grob(val): - "First frob and then clear val" - mymodule.frob(val) - val.clear() - - mymodule.frob = lambda val: val - mymodule.grob = grob - mymodule.date = date - - class TestCase(unittest2.TestCase): - def run(self): - result = unittest2.TestResult() - out = unittest2.TestCase.run(self, result) - assert result.wasSuccessful() - - from mock import inPy3k - - - -For comprehensive examples, see the unit tests included in the full source -distribution. - -Here are some more examples for some slightly more advanced scenarios than in -the :ref:`getting started <getting-started>` guide. - - -Mocking chained calls -===================== - -Mocking chained calls is actually straightforward with mock once you -understand the :attr:`~Mock.return_value` attribute. When a mock is called for -the first time, or you fetch its `return_value` before it has been called, a -new `Mock` is created. - -This means that you can see how the object returned from a call to a mocked -object has been used by interrogating the `return_value` mock: - -.. doctest:: - - >>> mock = Mock() - >>> mock().foo(a=2, b=3) - <Mock name='mock().foo()' id='...'> - >>> mock.return_value.foo.assert_called_with(a=2, b=3) - -From here it is a simple step to configure and then make assertions about -chained calls. Of course another alternative is writing your code in a more -testable way in the first place... - -So, suppose we have some code that looks a little bit like this: - -.. doctest:: - - >>> class Something(object): - ... def __init__(self): - ... self.backend = BackendProvider() - ... def method(self): - ... response = self.backend.get_endpoint('foobar').create_call('spam', 'eggs').start_call() - ... # more code - -Assuming that `BackendProvider` is already well tested, how do we test -`method()`? Specifically, we want to test that the code section `# more -code` uses the response object in the correct way. - -As this chain of calls is made from an instance attribute we can monkey patch -the `backend` attribute on a `Something` instance. In this particular case -we are only interested in the return value from the final call to -`start_call` so we don't have much configuration to do. Let's assume the -object it returns is 'file-like', so we'll ensure that our response object -uses the builtin `file` as its `spec`. - -To do this we create a mock instance as our mock backend and create a mock -response object for it. To set the response as the return value for that final -`start_call` we could do this: - - `mock_backend.get_endpoint.return_value.create_call.return_value.start_call.return_value = mock_response`. - -We can do that in a slightly nicer way using the :meth:`~Mock.configure_mock` -method to directly set the return value for us: - -.. doctest:: - - >>> something = Something() - >>> mock_response = Mock(spec=file) - >>> mock_backend = Mock() - >>> config = {'get_endpoint.return_value.create_call.return_value.start_call.return_value': mock_response} - >>> mock_backend.configure_mock(**config) - -With these we monkey patch the "mock backend" in place and can make the real -call: - -.. doctest:: - - >>> something.backend = mock_backend - >>> something.method() - -Using :attr:`~Mock.mock_calls` we can check the chained call with a single -assert. A chained call is several calls in one line of code, so there will be -several entries in `mock_calls`. We can use :meth:`call.call_list` to create -this list of calls for us: - -.. doctest:: - - >>> chained = call.get_endpoint('foobar').create_call('spam', 'eggs').start_call() - >>> call_list = chained.call_list() - >>> assert mock_backend.mock_calls == call_list - - -Partial mocking -=============== - -In some tests I wanted to mock out a call to `datetime.date.today() -<http://docs.python.org/library/datetime.html#datetime.date.today>`_ to return -a known date, but I didn't want to prevent the code under test from -creating new date objects. Unfortunately `datetime.date` is written in C, and -so I couldn't just monkey-patch out the static `date.today` method. - -I found a simple way of doing this that involved effectively wrapping the date -class with a mock, but passing through calls to the constructor to the real -class (and returning real instances). - -The :func:`patch decorator <patch>` is used here to -mock out the `date` class in the module under test. The :attr:`side_effect` -attribute on the mock date class is then set to a lambda function that returns -a real date. When the mock date class is called a real date will be -constructed and returned by `side_effect`. - -.. doctest:: - - >>> from datetime import date - >>> with patch('mymodule.date') as mock_date: - ... mock_date.today.return_value = date(2010, 10, 8) - ... mock_date.side_effect = lambda *args, **kw: date(*args, **kw) - ... - ... assert mymodule.date.today() == date(2010, 10, 8) - ... assert mymodule.date(2009, 6, 8) == date(2009, 6, 8) - ... - -Note that we don't patch `datetime.date` globally, we patch `date` in the -module that *uses* it. See :ref:`where to patch <where-to-patch>`. - -When `date.today()` is called a known date is returned, but calls to the -`date(...)` constructor still return normal dates. Without this you can find -yourself having to calculate an expected result using exactly the same -algorithm as the code under test, which is a classic testing anti-pattern. - -Calls to the date constructor are recorded in the `mock_date` attributes -(`call_count` and friends) which may also be useful for your tests. - -An alternative way of dealing with mocking dates, or other builtin classes, -is discussed in `this blog entry -<http://williamjohnbert.com/2011/07/how-to-unit-testing-in-django-with-mocking-and-patching/>`_. - - -Mocking a Generator Method -========================== - -A Python generator is a function or method that uses the `yield statement -<http://docs.python.org/reference/simple_stmts.html#the-yield-statement>`_ to -return a series of values when iterated over [#]_. - -A generator method / function is called to return the generator object. It is -the generator object that is then iterated over. The protocol method for -iteration is `__iter__ -<http://docs.python.org/library/stdtypes.html#container.__iter__>`_, so we can -mock this using a `MagicMock`. - -Here's an example class with an "iter" method implemented as a generator: - -.. doctest:: - - >>> class Foo(object): - ... def iter(self): - ... for i in [1, 2, 3]: - ... yield i - ... - >>> foo = Foo() - >>> list(foo.iter()) - [1, 2, 3] - - -How would we mock this class, and in particular its "iter" method? - -To configure the values returned from the iteration (implicit in the call to -`list`), we need to configure the object returned by the call to `foo.iter()`. - -.. doctest:: - - >>> mock_foo = MagicMock() - >>> mock_foo.iter.return_value = iter([1, 2, 3]) - >>> list(mock_foo.iter()) - [1, 2, 3] - -.. [#] There are also generator expressions and more `advanced uses - <http://www.dabeaz.com/coroutines/index.html>`_ of generators, but we aren't - concerned about them here. A very good introduction to generators and how - powerful they are is: `Generator Tricks for Systems Programmers - <http://www.dabeaz.com/generators/>`_. - - -Applying the same patch to every test method -============================================ - -If you want several patches in place for multiple test methods the obvious way -is to apply the patch decorators to every method. This can feel like unnecessary -repetition. For Python 2.6 or more recent you can use `patch` (in all its -various forms) as a class decorator. This applies the patches to all test -methods on the class. A test method is identified by methods whose names start -with `test`: - -.. doctest:: - - >>> @patch('mymodule.SomeClass') - ... class MyTest(TestCase): - ... - ... def test_one(self, MockSomeClass): - ... self.assertTrue(mymodule.SomeClass is MockSomeClass) - ... - ... def test_two(self, MockSomeClass): - ... self.assertTrue(mymodule.SomeClass is MockSomeClass) - ... - ... def not_a_test(self): - ... return 'something' - ... - >>> MyTest('test_one').test_one() - >>> MyTest('test_two').test_two() - >>> MyTest('test_two').not_a_test() - 'something' - -An alternative way of managing patches is to use the :ref:`start-and-stop`. -These allow you to move the patching into your `setUp` and `tearDown` methods. - -.. doctest:: - - >>> class MyTest(TestCase): - ... def setUp(self): - ... self.patcher = patch('mymodule.foo') - ... self.mock_foo = self.patcher.start() - ... - ... def test_foo(self): - ... self.assertTrue(mymodule.foo is self.mock_foo) - ... - ... def tearDown(self): - ... self.patcher.stop() - ... - >>> MyTest('test_foo').run() - -If you use this technique you must ensure that the patching is "undone" by -calling `stop`. This can be fiddlier than you might think, because if an -exception is raised in the setUp then tearDown is not called. `unittest2 -<http://pypi.python.org/pypi/unittest2>`_ cleanup functions make this simpler: - - -.. doctest:: - - >>> class MyTest(TestCase): - ... def setUp(self): - ... patcher = patch('mymodule.foo') - ... self.addCleanup(patcher.stop) - ... self.mock_foo = patcher.start() - ... - ... def test_foo(self): - ... self.assertTrue(mymodule.foo is self.mock_foo) - ... - >>> MyTest('test_foo').run() - - -Mocking Unbound Methods -======================= - -Whilst writing tests today I needed to patch an *unbound method* (patching the -method on the class rather than on the instance). I needed self to be passed -in as the first argument because I want to make asserts about which objects -were calling this particular method. The issue is that you can't patch with a -mock for this, because if you replace an unbound method with a mock it doesn't -become a bound method when fetched from the instance, and so it doesn't get -self passed in. The workaround is to patch the unbound method with a real -function instead. The :func:`patch` decorator makes it so simple to -patch out methods with a mock that having to create a real function becomes a -nuisance. - -If you pass `autospec=True` to patch then it does the patching with a -*real* function object. This function object has the same signature as the one -it is replacing, but delegates to a mock under the hood. You still get your -mock auto-created in exactly the same way as before. What it means though, is -that if you use it to patch out an unbound method on a class the mocked -function will be turned into a bound method if it is fetched from an instance. -It will have `self` passed in as the first argument, which is exactly what I -wanted: - -.. doctest:: - - >>> class Foo(object): - ... def foo(self): - ... pass - ... - >>> with patch.object(Foo, 'foo', autospec=True) as mock_foo: - ... mock_foo.return_value = 'foo' - ... foo = Foo() - ... foo.foo() - ... - 'foo' - >>> mock_foo.assert_called_once_with(foo) - -If we don't use `autospec=True` then the unbound method is patched out -with a Mock instance instead, and isn't called with `self`. - - -Checking multiple calls with mock -================================= - -mock has a nice API for making assertions about how your mock objects are used. - -.. doctest:: - - >>> mock = Mock() - >>> mock.foo_bar.return_value = None - >>> mock.foo_bar('baz', spam='eggs') - >>> mock.foo_bar.assert_called_with('baz', spam='eggs') - -If your mock is only being called once you can use the -:meth:`assert_called_once_with` method that also asserts that the -:attr:`call_count` is one. - -.. doctest:: - - >>> mock.foo_bar.assert_called_once_with('baz', spam='eggs') - >>> mock.foo_bar() - >>> mock.foo_bar.assert_called_once_with('baz', spam='eggs') - Traceback (most recent call last): - ... - AssertionError: Expected to be called once. Called 2 times. - -Both `assert_called_with` and `assert_called_once_with` make assertions about -the *most recent* call. If your mock is going to be called several times, and -you want to make assertions about *all* those calls you can use -:attr:`~Mock.call_args_list`: - -.. doctest:: - - >>> mock = Mock(return_value=None) - >>> mock(1, 2, 3) - >>> mock(4, 5, 6) - >>> mock() - >>> mock.call_args_list - [call(1, 2, 3), call(4, 5, 6), call()] - -The :data:`call` helper makes it easy to make assertions about these calls. You -can build up a list of expected calls and compare it to `call_args_list`. This -looks remarkably similar to the repr of the `call_args_list`: - -.. doctest:: - - >>> expected = [call(1, 2, 3), call(4, 5, 6), call()] - >>> mock.call_args_list == expected - True - - -Coping with mutable arguments -============================= - -Another situation is rare, but can bite you, is when your mock is called with -mutable arguments. `call_args` and `call_args_list` store *references* to the -arguments. If the arguments are mutated by the code under test then you can no -longer make assertions about what the values were when the mock was called. - -Here's some example code that shows the problem. Imagine the following functions -defined in 'mymodule':: - - def frob(val): - pass - - def grob(val): - "First frob and then clear val" - frob(val) - val.clear() - -When we try to test that `grob` calls `frob` with the correct argument look -what happens: - -.. doctest:: - - >>> with patch('mymodule.frob') as mock_frob: - ... val = set([6]) - ... mymodule.grob(val) - ... - >>> val - set([]) - >>> mock_frob.assert_called_with(set([6])) - Traceback (most recent call last): - ... - AssertionError: Expected: ((set([6]),), {}) - Called with: ((set([]),), {}) - -One possibility would be for mock to copy the arguments you pass in. This -could then cause problems if you do assertions that rely on object identity -for equality. - -Here's one solution that uses the :attr:`side_effect` -functionality. If you provide a `side_effect` function for a mock then -`side_effect` will be called with the same args as the mock. This gives us an -opportunity to copy the arguments and store them for later assertions. In this -example I'm using *another* mock to store the arguments so that I can use the -mock methods for doing the assertion. Again a helper function sets this up for -me. - -.. doctest:: - - >>> from copy import deepcopy - >>> from mock import Mock, patch, DEFAULT - >>> def copy_call_args(mock): - ... new_mock = Mock() - ... def side_effect(*args, **kwargs): - ... args = deepcopy(args) - ... kwargs = deepcopy(kwargs) - ... new_mock(*args, **kwargs) - ... return DEFAULT - ... mock.side_effect = side_effect - ... return new_mock - ... - >>> with patch('mymodule.frob') as mock_frob: - ... new_mock = copy_call_args(mock_frob) - ... val = set([6]) - ... mymodule.grob(val) - ... - >>> new_mock.assert_called_with(set([6])) - >>> new_mock.call_args - call(set([6])) - -`copy_call_args` is called with the mock that will be called. It returns a new -mock that we do the assertion on. The `side_effect` function makes a copy of -the args and calls our `new_mock` with the copy. - -.. note:: - - If your mock is only going to be used once there is an easier way of - checking arguments at the point they are called. You can simply do the - checking inside a `side_effect` function. - - .. doctest:: - - >>> def side_effect(arg): - ... assert arg == set([6]) - ... - >>> mock = Mock(side_effect=side_effect) - >>> mock(set([6])) - >>> mock(set()) - Traceback (most recent call last): - ... - AssertionError - -An alternative approach is to create a subclass of `Mock` or `MagicMock` that -copies (using `copy.deepcopy -<http://docs.python.org/library/copy.html#copy.deepcopy>`_) the arguments. -Here's an example implementation: - -.. doctest:: - - >>> from copy import deepcopy - >>> class CopyingMock(MagicMock): - ... def __call__(self, *args, **kwargs): - ... args = deepcopy(args) - ... kwargs = deepcopy(kwargs) - ... return super(CopyingMock, self).__call__(*args, **kwargs) - ... - >>> c = CopyingMock(return_value=None) - >>> arg = set() - >>> c(arg) - >>> arg.add(1) - >>> c.assert_called_with(set()) - >>> c.assert_called_with(arg) - Traceback (most recent call last): - ... - AssertionError: Expected call: mock(set([1])) - Actual call: mock(set([])) - >>> c.foo - <CopyingMock name='mock.foo' id='...'> - -When you subclass `Mock` or `MagicMock` all dynamically created attributes, -and the `return_value` will use your subclass automatically. That means all -children of a `CopyingMock` will also have the type `CopyingMock`. - - -Raising exceptions on attribute access -====================================== - -You can use :class:`PropertyMock` to mimic the behaviour of properties. This -includes raising exceptions when an attribute is accessed. - -Here's an example raising a `ValueError` when the 'foo' attribute is accessed: - -.. doctest:: - - >>> m = MagicMock() - >>> p = PropertyMock(side_effect=ValueError) - >>> type(m).foo = p - >>> m.foo - Traceback (most recent call last): - .... - ValueError - -Because every mock object has its own type, a new subclass of whichever mock -class you're using, all mock objects are isolated from each other. You can -safely attach properties (or other descriptors or whatever you want in fact) -to `type(mock)` without affecting other mock objects. - - -Multiple calls with different effects -===================================== - -.. note:: - - In mock 1.0 the handling of iterable `side_effect` was changed. Any - exceptions in the iterable will be raised instead of returned. - -Handling code that needs to behave differently on subsequent calls during the -test can be tricky. For example you may have a function that needs to raise -an exception the first time it is called but returns a response on the second -call (testing retry behaviour). - -One approach is to use a :attr:`side_effect` function that replaces itself. The -first time it is called the `side_effect` sets a new `side_effect` that will -be used for the second call. It then raises an exception: - -.. doctest:: - - >>> def side_effect(*args): - ... def second_call(*args): - ... return 'response' - ... mock.side_effect = second_call - ... raise Exception('boom') - ... - >>> mock = Mock(side_effect=side_effect) - >>> mock('first') - Traceback (most recent call last): - ... - Exception: boom - >>> mock('second') - 'response' - >>> mock.assert_called_with('second') - -Another perfectly valid way would be to pop return values from a list. If the -return value is an exception, raise it instead of returning it: - -.. doctest:: - - >>> returns = [Exception('boom'), 'response'] - >>> def side_effect(*args): - ... result = returns.pop(0) - ... if isinstance(result, Exception): - ... raise result - ... return result - ... - >>> mock = Mock(side_effect=side_effect) - >>> mock('first') - Traceback (most recent call last): - ... - Exception: boom - >>> mock('second') - 'response' - >>> mock.assert_called_with('second') - -Which approach you prefer is a matter of taste. The first approach is actually -a line shorter but maybe the second approach is more readable. - - -Nesting Patches -=============== - -Using patch as a context manager is nice, but if you do multiple patches you -can end up with nested with statements indenting further and further to the -right: - -.. doctest:: - - >>> class MyTest(TestCase): - ... - ... def test_foo(self): - ... with patch('mymodule.Foo') as mock_foo: - ... with patch('mymodule.Bar') as mock_bar: - ... with patch('mymodule.Spam') as mock_spam: - ... assert mymodule.Foo is mock_foo - ... assert mymodule.Bar is mock_bar - ... assert mymodule.Spam is mock_spam - ... - >>> original = mymodule.Foo - >>> MyTest('test_foo').test_foo() - >>> assert mymodule.Foo is original - -With unittest2_ `cleanup` functions and the :ref:`start-and-stop` we can -achieve the same effect without the nested indentation. A simple helper -method, `create_patch`, puts the patch in place and returns the created mock -for us: - -.. doctest:: - - >>> class MyTest(TestCase): - ... - ... def create_patch(self, name): - ... patcher = patch(name) - ... thing = patcher.start() - ... self.addCleanup(patcher.stop) - ... return thing - ... - ... def test_foo(self): - ... mock_foo = self.create_patch('mymodule.Foo') - ... mock_bar = self.create_patch('mymodule.Bar') - ... mock_spam = self.create_patch('mymodule.Spam') - ... - ... assert mymodule.Foo is mock_foo - ... assert mymodule.Bar is mock_bar - ... assert mymodule.Spam is mock_spam - ... - >>> original = mymodule.Foo - >>> MyTest('test_foo').run() - >>> assert mymodule.Foo is original - - -Mocking a dictionary with MagicMock -=================================== - -You may want to mock a dictionary, or other container object, recording all -access to it whilst having it still behave like a dictionary. - -We can do this with :class:`MagicMock`, which will behave like a dictionary, -and using :data:`~Mock.side_effect` to delegate dictionary access to a real -underlying dictionary that is under our control. - -When the `__getitem__` and `__setitem__` methods of our `MagicMock` are called -(normal dictionary access) then `side_effect` is called with the key (and in -the case of `__setitem__` the value too). We can also control what is returned. - -After the `MagicMock` has been used we can use attributes like -:data:`~Mock.call_args_list` to assert about how the dictionary was used: - -.. doctest:: - - >>> my_dict = {'a': 1, 'b': 2, 'c': 3} - >>> def getitem(name): - ... return my_dict[name] - ... - >>> def setitem(name, val): - ... my_dict[name] = val - ... - >>> mock = MagicMock() - >>> mock.__getitem__.side_effect = getitem - >>> mock.__setitem__.side_effect = setitem - -.. note:: - - An alternative to using `MagicMock` is to use `Mock` and *only* provide - the magic methods you specifically want: - - .. doctest:: - - >>> mock = Mock() - >>> mock.__setitem__ = Mock(side_effect=getitem) - >>> mock.__getitem__ = Mock(side_effect=setitem) - - A *third* option is to use `MagicMock` but passing in `dict` as the `spec` - (or `spec_set`) argument so that the `MagicMock` created only has - dictionary magic methods available: - - .. doctest:: - - >>> mock = MagicMock(spec_set=dict) - >>> mock.__getitem__.side_effect = getitem - >>> mock.__setitem__.side_effect = setitem - -With these side effect functions in place, the `mock` will behave like a normal -dictionary but recording the access. It even raises a `KeyError` if you try -to access a key that doesn't exist. - -.. doctest:: - - >>> mock['a'] - 1 - >>> mock['c'] - 3 - >>> mock['d'] - Traceback (most recent call last): - ... - KeyError: 'd' - >>> mock['b'] = 'fish' - >>> mock['d'] = 'eggs' - >>> mock['b'] - 'fish' - >>> mock['d'] - 'eggs' - -After it has been used you can make assertions about the access using the normal -mock methods and attributes: - -.. doctest:: - - >>> mock.__getitem__.call_args_list - [call('a'), call('c'), call('d'), call('b'), call('d')] - >>> mock.__setitem__.call_args_list - [call('b', 'fish'), call('d', 'eggs')] - >>> my_dict - {'a': 1, 'c': 3, 'b': 'fish', 'd': 'eggs'} - - -Mock subclasses and their attributes -==================================== - -There are various reasons why you might want to subclass `Mock`. One reason -might be to add helper methods. Here's a silly example: - -.. doctest:: - - >>> class MyMock(MagicMock): - ... def has_been_called(self): - ... return self.called - ... - >>> mymock = MyMock(return_value=None) - >>> mymock - <MyMock id='...'> - >>> mymock.has_been_called() - False - >>> mymock() - >>> mymock.has_been_called() - True - -The standard behaviour for `Mock` instances is that attributes and the return -value mocks are of the same type as the mock they are accessed on. This ensures -that `Mock` attributes are `Mocks` and `MagicMock` attributes are `MagicMocks` -[#]_. So if you're subclassing to add helper methods then they'll also be -available on the attributes and return value mock of instances of your -subclass. - -.. doctest:: - - >>> mymock.foo - <MyMock name='mock.foo' id='...'> - >>> mymock.foo.has_been_called() - False - >>> mymock.foo() - <MyMock name='mock.foo()' id='...'> - >>> mymock.foo.has_been_called() - True - -Sometimes this is inconvenient. For example, `one user -<https://code.google.com/p/mock/issues/detail?id=105>`_ is subclassing mock to -created a `Twisted adaptor -<http://twistedmatrix.com/documents/11.0.0/api/twisted.python.components.html>`_. -Having this applied to attributes too actually causes errors. - -`Mock` (in all its flavours) uses a method called `_get_child_mock` to create -these "sub-mocks" for attributes and return values. You can prevent your -subclass being used for attributes by overriding this method. The signature is -that it takes arbitrary keyword arguments (`**kwargs`) which are then passed -onto the mock constructor: - -.. doctest:: - - >>> class Subclass(MagicMock): - ... def _get_child_mock(self, **kwargs): - ... return MagicMock(**kwargs) - ... - >>> mymock = Subclass() - >>> mymock.foo - <MagicMock name='mock.foo' id='...'> - >>> assert isinstance(mymock, Subclass) - >>> assert not isinstance(mymock.foo, Subclass) - >>> assert not isinstance(mymock(), Subclass) - -.. [#] An exception to this rule are the non-callable mocks. Attributes use the - callable variant because otherwise non-callable mocks couldn't have callable - methods. - - -Mocking imports with patch.dict -=============================== - -One situation where mocking can be hard is where you have a local import inside -a function. These are harder to mock because they aren't using an object from -the module namespace that we can patch out. - -Generally local imports are to be avoided. They are sometimes done to prevent -circular dependencies, for which there is *usually* a much better way to solve -the problem (refactor the code) or to prevent "up front costs" by delaying the -import. This can also be solved in better ways than an unconditional local -import (store the module as a class or module attribute and only do the import -on first use). - -That aside there is a way to use `mock` to affect the results of an import. -Importing fetches an *object* from the `sys.modules` dictionary. Note that it -fetches an *object*, which need not be a module. Importing a module for the -first time results in a module object being put in `sys.modules`, so usually -when you import something you get a module back. This need not be the case -however. - -This means you can use :func:`patch.dict` to *temporarily* put a mock in place -in `sys.modules`. Any imports whilst this patch is active will fetch the mock. -When the patch is complete (the decorated function exits, the with statement -body is complete or `patcher.stop()` is called) then whatever was there -previously will be restored safely. - -Here's an example that mocks out the 'fooble' module. - -.. doctest:: - - >>> mock = Mock() - >>> with patch.dict('sys.modules', {'fooble': mock}): - ... import fooble - ... fooble.blob() - ... - <Mock name='mock.blob()' id='...'> - >>> assert 'fooble' not in sys.modules - >>> mock.blob.assert_called_once_with() - -As you can see the `import fooble` succeeds, but on exit there is no 'fooble' -left in `sys.modules`. - -This also works for the `from module import name` form: - -.. doctest:: - - >>> mock = Mock() - >>> with patch.dict('sys.modules', {'fooble': mock}): - ... from fooble import blob - ... blob.blip() - ... - <Mock name='mock.blob.blip()' id='...'> - >>> mock.blob.blip.assert_called_once_with() - -With slightly more work you can also mock package imports: - -.. doctest:: - - >>> mock = Mock() - >>> modules = {'package': mock, 'package.module': mock.module} - >>> with patch.dict('sys.modules', modules): - ... from package.module import fooble - ... fooble() - ... - <Mock name='mock.module.fooble()' id='...'> - >>> mock.module.fooble.assert_called_once_with() - - -Tracking order of calls and less verbose call assertions -======================================================== - -The :class:`Mock` class allows you to track the *order* of method calls on -your mock objects through the :attr:`~Mock.method_calls` attribute. This -doesn't allow you to track the order of calls between separate mock objects, -however we can use :attr:`~Mock.mock_calls` to achieve the same effect. - -Because mocks track calls to child mocks in `mock_calls`, and accessing an -arbitrary attribute of a mock creates a child mock, we can create our separate -mocks from a parent one. Calls to those child mock will then all be recorded, -in order, in the `mock_calls` of the parent: - -.. doctest:: - - >>> manager = Mock() - >>> mock_foo = manager.foo - >>> mock_bar = manager.bar - - >>> mock_foo.something() - <Mock name='mock.foo.something()' id='...'> - >>> mock_bar.other.thing() - <Mock name='mock.bar.other.thing()' id='...'> - - >>> manager.mock_calls - [call.foo.something(), call.bar.other.thing()] - -We can then assert about the calls, including the order, by comparing with -the `mock_calls` attribute on the manager mock: - -.. doctest:: - - >>> expected_calls = [call.foo.something(), call.bar.other.thing()] - >>> manager.mock_calls == expected_calls - True - -If `patch` is creating, and putting in place, your mocks then you can attach -them to a manager mock using the :meth:`~Mock.attach_mock` method. After -attaching calls will be recorded in `mock_calls` of the manager. - -.. doctest:: - - >>> manager = MagicMock() - >>> with patch('mymodule.Class1') as MockClass1: - ... with patch('mymodule.Class2') as MockClass2: - ... manager.attach_mock(MockClass1, 'MockClass1') - ... manager.attach_mock(MockClass2, 'MockClass2') - ... MockClass1().foo() - ... MockClass2().bar() - ... - <MagicMock name='mock.MockClass1().foo()' id='...'> - <MagicMock name='mock.MockClass2().bar()' id='...'> - >>> manager.mock_calls - [call.MockClass1(), - call.MockClass1().foo(), - call.MockClass2(), - call.MockClass2().bar()] - -If many calls have been made, but you're only interested in a particular -sequence of them then an alternative is to use the -:meth:`~Mock.assert_has_calls` method. This takes a list of calls (constructed -with the :data:`call` object). If that sequence of calls are in -:attr:`~Mock.mock_calls` then the assert succeeds. - -.. doctest:: - - >>> m = MagicMock() - >>> m().foo().bar().baz() - <MagicMock name='mock().foo().bar().baz()' id='...'> - >>> m.one().two().three() - <MagicMock name='mock.one().two().three()' id='...'> - >>> calls = call.one().two().three().call_list() - >>> m.assert_has_calls(calls) - -Even though the chained call `m.one().two().three()` aren't the only calls that -have been made to the mock, the assert still succeeds. - -Sometimes a mock may have several calls made to it, and you are only interested -in asserting about *some* of those calls. You may not even care about the -order. In this case you can pass `any_order=True` to `assert_has_calls`: - -.. doctest:: - - >>> m = MagicMock() - >>> m(1), m.two(2, 3), m.seven(7), m.fifty('50') - (...) - >>> calls = [call.fifty('50'), call(1), call.seven(7)] - >>> m.assert_has_calls(calls, any_order=True) - - -More complex argument matching -============================== - -Using the same basic concept as `ANY` we can implement matchers to do more -complex assertions on objects used as arguments to mocks. - -Suppose we expect some object to be passed to a mock that by default -compares equal based on object identity (which is the Python default for user -defined classes). To use :meth:`~Mock.assert_called_with` we would need to pass -in the exact same object. If we are only interested in some of the attributes -of this object then we can create a matcher that will check these attributes -for us. - -You can see in this example how a 'standard' call to `assert_called_with` isn't -sufficient: - -.. doctest:: - - >>> class Foo(object): - ... def __init__(self, a, b): - ... self.a, self.b = a, b - ... - >>> mock = Mock(return_value=None) - >>> mock(Foo(1, 2)) - >>> mock.assert_called_with(Foo(1, 2)) - Traceback (most recent call last): - ... - AssertionError: Expected: call(<__main__.Foo object at 0x...>) - Actual call: call(<__main__.Foo object at 0x...>) - -A comparison function for our `Foo` class might look something like this: - -.. doctest:: - - >>> def compare(self, other): - ... if not type(self) == type(other): - ... return False - ... if self.a != other.a: - ... return False - ... if self.b != other.b: - ... return False - ... return True - ... - -And a matcher object that can use comparison functions like this for its -equality operation would look something like this: - -.. doctest:: - - >>> class Matcher(object): - ... def __init__(self, compare, some_obj): - ... self.compare = compare - ... self.some_obj = some_obj - ... def __eq__(self, other): - ... return self.compare(self.some_obj, other) - ... - -Putting all this together: - -.. doctest:: - - >>> match_foo = Matcher(compare, Foo(1, 2)) - >>> mock.assert_called_with(match_foo) - -The `Matcher` is instantiated with our compare function and the `Foo` object -we want to compare against. In `assert_called_with` the `Matcher` equality -method will be called, which compares the object the mock was called with -against the one we created our matcher with. If they match then -`assert_called_with` passes, and if they don't an `AssertionError` is raised: - -.. doctest:: - - >>> match_wrong = Matcher(compare, Foo(3, 4)) - >>> mock.assert_called_with(match_wrong) - Traceback (most recent call last): - ... - AssertionError: Expected: ((<Matcher object at 0x...>,), {}) - Called with: ((<Foo object at 0x...>,), {}) - -With a bit of tweaking you could have the comparison function raise the -`AssertionError` directly and provide a more useful failure message. - -As of version 1.5, the Python testing library `PyHamcrest -<http://pypi.python.org/pypi/PyHamcrest>`_ provides similar functionality, -that may be useful here, in the form of its equality matcher -(`hamcrest.library.integration.match_equality -<http://packages.python.org/PyHamcrest/integration.html#hamcrest.library.integration.match_equality>`_). - - -Less verbose configuration of mock objects -========================================== - -This recipe, for easier configuration of mock objects, is now part of `Mock`. -See the :meth:`~Mock.configure_mock` method. - - -Matching any argument in assertions -=================================== - -This example is now built in to mock. See :data:`ANY`. - - -Mocking Properties -================== - -This example is now built in to mock. See :class:`PropertyMock`. - - -Mocking open -============ - -This example is now built in to mock. See :func:`mock_open`. - - -Mocks without some attributes -============================= - -This example is now built in to mock. See :ref:`deleting-attributes`.
http://git-wip-us.apache.org/repos/asf/incubator-atlas/blob/c219798b/src/test/mock/docs/getting-started.txt ---------------------------------------------------------------------- diff --git a/src/test/mock/docs/getting-started.txt b/src/test/mock/docs/getting-started.txt deleted file mode 100644 index 1b5d289..0000000 --- a/src/test/mock/docs/getting-started.txt +++ /dev/null @@ -1,479 +0,0 @@ -=========================== - Getting Started with Mock -=========================== - -.. _getting-started: - -.. index:: Getting Started - -.. testsetup:: - - class SomeClass(object): - static_method = None - class_method = None - attribute = None - - sys.modules['package'] = package = Mock(name='package') - sys.modules['package.module'] = module = package.module - sys.modules['module'] = package.module - - -Using Mock -========== - -Mock Patching Methods ---------------------- - -Common uses for :class:`Mock` objects include: - -* Patching methods -* Recording method calls on objects - -You might want to replace a method on an object to check that -it is called with the correct arguments by another part of the system: - -.. doctest:: - - >>> real = SomeClass() - >>> real.method = MagicMock(name='method') - >>> real.method(3, 4, 5, key='value') - <MagicMock name='method()' id='...'> - -Once our mock has been used (`real.method` in this example) it has methods -and attributes that allow you to make assertions about how it has been used. - -.. note:: - - In most of these examples the :class:`Mock` and :class:`MagicMock` classes - are interchangeable. As the `MagicMock` is the more capable class it makes - a sensible one to use by default. - -Once the mock has been called its :attr:`~Mock.called` attribute is set to -`True`. More importantly we can use the :meth:`~Mock.assert_called_with` or -:meth:`~Mock.assert_called_once_with` method to check that it was called with -the correct arguments. - -This example tests that calling `ProductionClass().method` results in a call to -the `something` method: - -.. doctest:: - - >>> from mock import MagicMock - >>> class ProductionClass(object): - ... def method(self): - ... self.something(1, 2, 3) - ... def something(self, a, b, c): - ... pass - ... - >>> real = ProductionClass() - >>> real.something = MagicMock() - >>> real.method() - >>> real.something.assert_called_once_with(1, 2, 3) - - - -Mock for Method Calls on an Object ----------------------------------- - -In the last example we patched a method directly on an object to check that it -was called correctly. Another common use case is to pass an object into a -method (or some part of the system under test) and then check that it is used -in the correct way. - -The simple `ProductionClass` below has a `closer` method. If it is called with -an object then it calls `close` on it. - -.. doctest:: - - >>> class ProductionClass(object): - ... def closer(self, something): - ... something.close() - ... - -So to test it we need to pass in an object with a `close` method and check -that it was called correctly. - -.. doctest:: - - >>> real = ProductionClass() - >>> mock = Mock() - >>> real.closer(mock) - >>> mock.close.assert_called_with() - -We don't have to do any work to provide the 'close' method on our mock. -Accessing close creates it. So, if 'close' hasn't already been called then -accessing it in the test will create it, but :meth:`~Mock.assert_called_with` -will raise a failure exception. - - -Mocking Classes ---------------- - -A common use case is to mock out classes instantiated by your code under test. -When you patch a class, then that class is replaced with a mock. Instances -are created by *calling the class*. This means you access the "mock instance" -by looking at the return value of the mocked class. - -In the example below we have a function `some_function` that instantiates `Foo` -and calls a method on it. The call to `patch` replaces the class `Foo` with a -mock. The `Foo` instance is the result of calling the mock, so it is configured -by modifying the mock :attr:`~Mock.return_value`. - -.. doctest:: - - >>> def some_function(): - ... instance = module.Foo() - ... return instance.method() - ... - >>> with patch('module.Foo') as mock: - ... instance = mock.return_value - ... instance.method.return_value = 'the result' - ... result = some_function() - ... assert result == 'the result' - - -Naming your mocks ------------------ - -It can be useful to give your mocks a name. The name is shown in the repr of -the mock and can be helpful when the mock appears in test failure messages. The -name is also propagated to attributes or methods of the mock: - -.. doctest:: - - >>> mock = MagicMock(name='foo') - >>> mock - <MagicMock name='foo' id='...'> - >>> mock.method - <MagicMock name='foo.method' id='...'> - - -Tracking all Calls ------------------- - -Often you want to track more than a single call to a method. The -:attr:`~Mock.mock_calls` attribute records all calls -to child attributes of the mock - and also to their children. - -.. doctest:: - - >>> mock = MagicMock() - >>> mock.method() - <MagicMock name='mock.method()' id='...'> - >>> mock.attribute.method(10, x=53) - <MagicMock name='mock.attribute.method()' id='...'> - >>> mock.mock_calls - [call.method(), call.attribute.method(10, x=53)] - -If you make an assertion about `mock_calls` and any unexpected methods -have been called, then the assertion will fail. This is useful because as well -as asserting that the calls you expected have been made, you are also checking -that they were made in the right order and with no additional calls: - -You use the :data:`call` object to construct lists for comparing with -`mock_calls`: - -.. doctest:: - - >>> expected = [call.method(), call.attribute.method(10, x=53)] - >>> mock.mock_calls == expected - True - - -Setting Return Values and Attributes ------------------------------------- - -Setting the return values on a mock object is trivially easy: - -.. doctest:: - - >>> mock = Mock() - >>> mock.return_value = 3 - >>> mock() - 3 - -Of course you can do the same for methods on the mock: - -.. doctest:: - - >>> mock = Mock() - >>> mock.method.return_value = 3 - >>> mock.method() - 3 - -The return value can also be set in the constructor: - -.. doctest:: - - >>> mock = Mock(return_value=3) - >>> mock() - 3 - -If you need an attribute setting on your mock, just do it: - -.. doctest:: - - >>> mock = Mock() - >>> mock.x = 3 - >>> mock.x - 3 - -Sometimes you want to mock up a more complex situation, like for example -`mock.connection.cursor().execute("SELECT 1")`. If we wanted this call to -return a list, then we have to configure the result of the nested call. - -We can use :data:`call` to construct the set of calls in a "chained call" like -this for easy assertion afterwards: - - -.. doctest:: - - >>> mock = Mock() - >>> cursor = mock.connection.cursor.return_value - >>> cursor.execute.return_value = ['foo'] - >>> mock.connection.cursor().execute("SELECT 1") - ['foo'] - >>> expected = call.connection.cursor().execute("SELECT 1").call_list() - >>> mock.mock_calls - [call.connection.cursor(), call.connection.cursor().execute('SELECT 1')] - >>> mock.mock_calls == expected - True - -It is the call to `.call_list()` that turns our call object into a list of -calls representing the chained calls. - - - -Raising exceptions with mocks ------------------------------ - -A useful attribute is :attr:`~Mock.side_effect`. If you set this to an -exception class or instance then the exception will be raised when the mock -is called. - -.. doctest:: - - >>> mock = Mock(side_effect=Exception('Boom!')) - >>> mock() - Traceback (most recent call last): - ... - Exception: Boom! - - -Side effect functions and iterables ------------------------------------ - -`side_effect` can also be set to a function or an iterable. The use case for -`side_effect` as an iterable is where your mock is going to be called several -times, and you want each call to return a different value. When you set -`side_effect` to an iterable every call to the mock returns the next value -from the iterable: - -.. doctest:: - - >>> mock = MagicMock(side_effect=[4, 5, 6]) - >>> mock() - 4 - >>> mock() - 5 - >>> mock() - 6 - - -For more advanced use cases, like dynamically varying the return values -depending on what the mock is called with, `side_effect` can be a function. -The function will be called with the same arguments as the mock. Whatever the -function returns is what the call returns: - -.. doctest:: - - >>> vals = {(1, 2): 1, (2, 3): 2} - >>> def side_effect(*args): - ... return vals[args] - ... - >>> mock = MagicMock(side_effect=side_effect) - >>> mock(1, 2) - 1 - >>> mock(2, 3) - 2 - - -Creating a Mock from an Existing Object ---------------------------------------- - -One problem with over use of mocking is that it couples your tests to the -implementation of your mocks rather than your real code. Suppose you have a -class that implements `some_method`. In a test for another class, you -provide a mock of this object that *also* provides `some_method`. If later -you refactor the first class, so that it no longer has `some_method` - then -your tests will continue to pass even though your code is now broken! - -`Mock` allows you to provide an object as a specification for the mock, -using the `spec` keyword argument. Accessing methods / attributes on the -mock that don't exist on your specification object will immediately raise an -attribute error. If you change the implementation of your specification, then -tests that use that class will start failing immediately without you having to -instantiate the class in those tests. - -.. doctest:: - - >>> mock = Mock(spec=SomeClass) - >>> mock.old_method() - Traceback (most recent call last): - ... - AttributeError: object has no attribute 'old_method' - -If you want a stronger form of specification that prevents the setting -of arbitrary attributes as well as the getting of them then you can use -`spec_set` instead of `spec`. - - - -Patch Decorators -================ - -.. note:: - - With `patch` it matters that you patch objects in the namespace where they - are looked up. This is normally straightforward, but for a quick guide - read :ref:`where to patch <where-to-patch>`. - - -A common need in tests is to patch a class attribute or a module attribute, -for example patching a builtin or patching a class in a module to test that it -is instantiated. Modules and classes are effectively global, so patching on -them has to be undone after the test or the patch will persist into other -tests and cause hard to diagnose problems. - -mock provides three convenient decorators for this: `patch`, `patch.object` and -`patch.dict`. `patch` takes a single string, of the form -`package.module.Class.attribute` to specify the attribute you are patching. It -also optionally takes a value that you want the attribute (or class or -whatever) to be replaced with. 'patch.object' takes an object and the name of -the attribute you would like patched, plus optionally the value to patch it -with. - -`patch.object`: - -.. doctest:: - - >>> original = SomeClass.attribute - >>> @patch.object(SomeClass, 'attribute', sentinel.attribute) - ... def test(): - ... assert SomeClass.attribute == sentinel.attribute - ... - >>> test() - >>> assert SomeClass.attribute == original - - >>> @patch('package.module.attribute', sentinel.attribute) - ... def test(): - ... from package.module import attribute - ... assert attribute is sentinel.attribute - ... - >>> test() - -If you are patching a module (including `__builtin__`) then use `patch` -instead of `patch.object`: - -.. doctest:: - - >>> mock = MagicMock(return_value = sentinel.file_handle) - >>> with patch('__builtin__.open', mock): - ... handle = open('filename', 'r') - ... - >>> mock.assert_called_with('filename', 'r') - >>> assert handle == sentinel.file_handle, "incorrect file handle returned" - -The module name can be 'dotted', in the form `package.module` if needed: - -.. doctest:: - - >>> @patch('package.module.ClassName.attribute', sentinel.attribute) - ... def test(): - ... from package.module import ClassName - ... assert ClassName.attribute == sentinel.attribute - ... - >>> test() - -A nice pattern is to actually decorate test methods themselves: - -.. doctest:: - - >>> class MyTest(unittest2.TestCase): - ... @patch.object(SomeClass, 'attribute', sentinel.attribute) - ... def test_something(self): - ... self.assertEqual(SomeClass.attribute, sentinel.attribute) - ... - >>> original = SomeClass.attribute - >>> MyTest('test_something').test_something() - >>> assert SomeClass.attribute == original - -If you want to patch with a Mock, you can use `patch` with only one argument -(or `patch.object` with two arguments). The mock will be created for you and -passed into the test function / method: - -.. doctest:: - - >>> class MyTest(unittest2.TestCase): - ... @patch.object(SomeClass, 'static_method') - ... def test_something(self, mock_method): - ... SomeClass.static_method() - ... mock_method.assert_called_with() - ... - >>> MyTest('test_something').test_something() - -You can stack up multiple patch decorators using this pattern: - -.. doctest:: - - >>> class MyTest(unittest2.TestCase): - ... @patch('package.module.ClassName1') - ... @patch('package.module.ClassName2') - ... def test_something(self, MockClass2, MockClass1): - ... self.assertTrue(package.module.ClassName1 is MockClass1) - ... self.assertTrue(package.module.ClassName2 is MockClass2) - ... - >>> MyTest('test_something').test_something() - -When you nest patch decorators the mocks are passed in to the decorated -function in the same order they applied (the normal *python* order that -decorators are applied). This means from the bottom up, so in the example -above the mock for `test_module.ClassName2` is passed in first. - -There is also :func:`patch.dict` for setting values in a dictionary just -during a scope and restoring the dictionary to its original state when the test -ends: - -.. doctest:: - - >>> foo = {'key': 'value'} - >>> original = foo.copy() - >>> with patch.dict(foo, {'newkey': 'newvalue'}, clear=True): - ... assert foo == {'newkey': 'newvalue'} - ... - >>> assert foo == original - -`patch`, `patch.object` and `patch.dict` can all be used as context managers. - -Where you use `patch` to create a mock for you, you can get a reference to the -mock using the "as" form of the with statement: - -.. doctest:: - - >>> class ProductionClass(object): - ... def method(self): - ... pass - ... - >>> with patch.object(ProductionClass, 'method') as mock_method: - ... mock_method.return_value = None - ... real = ProductionClass() - ... real.method(1, 2, 3) - ... - >>> mock_method.assert_called_with(1, 2, 3) - - -As an alternative `patch`, `patch.object` and `patch.dict` can be used as -class decorators. When used in this way it is the same as applying the -decorator indvidually to every method whose name starts with "test". - -For some more advanced examples, see the :ref:`further-examples` page. http://git-wip-us.apache.org/repos/asf/incubator-atlas/blob/c219798b/src/test/mock/docs/helpers.txt ---------------------------------------------------------------------- diff --git a/src/test/mock/docs/helpers.txt b/src/test/mock/docs/helpers.txt deleted file mode 100644 index 571b71d..0000000 --- a/src/test/mock/docs/helpers.txt +++ /dev/null @@ -1,583 +0,0 @@ -========= - Helpers -========= - -.. currentmodule:: mock - -.. testsetup:: - - mock.FILTER_DIR = True - from pprint import pprint as pp - original_dir = dir - def dir(obj): - print pp(original_dir(obj)) - - import urllib2 - __main__.urllib2 = urllib2 - -.. testcleanup:: - - dir = original_dir - mock.FILTER_DIR = True - - - -call -==== - -.. function:: call(*args, **kwargs) - - `call` is a helper object for making simpler assertions, for comparing - with :attr:`~Mock.call_args`, :attr:`~Mock.call_args_list`, - :attr:`~Mock.mock_calls` and :attr: `~Mock.method_calls`. `call` can also be - used with :meth:`~Mock.assert_has_calls`. - - .. doctest:: - - >>> m = MagicMock(return_value=None) - >>> m(1, 2, a='foo', b='bar') - >>> m() - >>> m.call_args_list == [call(1, 2, a='foo', b='bar'), call()] - True - -.. method:: call.call_list() - - For a call object that represents multiple calls, `call_list` - returns a list of all the intermediate calls as well as the - final call. - -`call_list` is particularly useful for making assertions on "chained calls". A -chained call is multiple calls on a single line of code. This results in -multiple entries in :attr:`~Mock.mock_calls` on a mock. Manually constructing -the sequence of calls can be tedious. - -:meth:`~call.call_list` can construct the sequence of calls from the same -chained call: - -.. doctest:: - - >>> m = MagicMock() - >>> m(1).method(arg='foo').other('bar')(2.0) - <MagicMock name='mock().method().other()()' id='...'> - >>> kall = call(1).method(arg='foo').other('bar')(2.0) - >>> kall.call_list() - [call(1), - call().method(arg='foo'), - call().method().other('bar'), - call().method().other()(2.0)] - >>> m.mock_calls == kall.call_list() - True - -.. _calls-as-tuples: - -A `call` object is either a tuple of (positional args, keyword args) or -(name, positional args, keyword args) depending on how it was constructed. When -you construct them yourself this isn't particularly interesting, but the `call` -objects that are in the :attr:`Mock.call_args`, :attr:`Mock.call_args_list` and -:attr:`Mock.mock_calls` attributes can be introspected to get at the individual -arguments they contain. - -The `call` objects in :attr:`Mock.call_args` and :attr:`Mock.call_args_list` -are two-tuples of (positional args, keyword args) whereas the `call` objects -in :attr:`Mock.mock_calls`, along with ones you construct yourself, are -three-tuples of (name, positional args, keyword args). - -You can use their "tupleness" to pull out the individual arguments for more -complex introspection and assertions. The positional arguments are a tuple -(an empty tuple if there are no positional arguments) and the keyword -arguments are a dictionary: - -.. doctest:: - - >>> m = MagicMock(return_value=None) - >>> m(1, 2, 3, arg='one', arg2='two') - >>> kall = m.call_args - >>> args, kwargs = kall - >>> args - (1, 2, 3) - >>> kwargs - {'arg2': 'two', 'arg': 'one'} - >>> args is kall[0] - True - >>> kwargs is kall[1] - True - - >>> m = MagicMock() - >>> m.foo(4, 5, 6, arg='two', arg2='three') - <MagicMock name='mock.foo()' id='...'> - >>> kall = m.mock_calls[0] - >>> name, args, kwargs = kall - >>> name - 'foo' - >>> args - (4, 5, 6) - >>> kwargs - {'arg2': 'three', 'arg': 'two'} - >>> name is m.mock_calls[0][0] - True - - -create_autospec -=============== - -.. function:: create_autospec(spec, spec_set=False, instance=False, **kwargs) - - Create a mock object using another object as a spec. Attributes on the - mock will use the corresponding attribute on the `spec` object as their - spec. - - Functions or methods being mocked will have their arguments checked to - ensure that they are called with the correct signature. - - If `spec_set` is `True` then attempting to set attributes that don't exist - on the spec object will raise an `AttributeError`. - - If a class is used as a spec then the return value of the mock (the - instance of the class) will have the same spec. You can use a class as the - spec for an instance object by passing `instance=True`. The returned mock - will only be callable if instances of the mock are callable. - - `create_autospec` also takes arbitrary keyword arguments that are passed to - the constructor of the created mock. - -See :ref:`auto-speccing` for examples of how to use auto-speccing with -`create_autospec` and the `autospec` argument to :func:`patch`. - - -ANY -=== - -.. data:: ANY - -Sometimes you may need to make assertions about *some* of the arguments in a -call to mock, but either not care about some of the arguments or want to pull -them individually out of :attr:`~Mock.call_args` and make more complex -assertions on them. - -To ignore certain arguments you can pass in objects that compare equal to -*everything*. Calls to :meth:`~Mock.assert_called_with` and -:meth:`~Mock.assert_called_once_with` will then succeed no matter what was -passed in. - -.. doctest:: - - >>> mock = Mock(return_value=None) - >>> mock('foo', bar=object()) - >>> mock.assert_called_once_with('foo', bar=ANY) - -`ANY` can also be used in comparisons with call lists like -:attr:`~Mock.mock_calls`: - -.. doctest:: - - >>> m = MagicMock(return_value=None) - >>> m(1) - >>> m(1, 2) - >>> m(object()) - >>> m.mock_calls == [call(1), call(1, 2), ANY] - True - - - -FILTER_DIR -========== - -.. data:: FILTER_DIR - -`FILTER_DIR` is a module level variable that controls the way mock objects -respond to `dir` (only for Python 2.6 or more recent). The default is `True`, -which uses the filtering described below, to only show useful members. If you -dislike this filtering, or need to switch it off for diagnostic purposes, then -set `mock.FILTER_DIR = False`. - -With filtering on, `dir(some_mock)` shows only useful attributes and will -include any dynamically created attributes that wouldn't normally be shown. -If the mock was created with a `spec` (or `autospec` of course) then all the -attributes from the original are shown, even if they haven't been accessed -yet: - -.. doctest:: - - >>> dir(Mock()) - ['assert_any_call', - 'assert_called_once_with', - 'assert_called_with', - 'assert_has_calls', - 'attach_mock', - ... - >>> import urllib2 - >>> dir(Mock(spec=urllib2)) - ['AbstractBasicAuthHandler', - 'AbstractDigestAuthHandler', - 'AbstractHTTPHandler', - 'BaseHandler', - ... - -Many of the not-very-useful (private to `Mock` rather than the thing being -mocked) underscore and double underscore prefixed attributes have been -filtered from the result of calling `dir` on a `Mock`. If you dislike this -behaviour you can switch it off by setting the module level switch -`FILTER_DIR`: - -.. doctest:: - - >>> import mock - >>> mock.FILTER_DIR = False - >>> dir(mock.Mock()) - ['_NonCallableMock__get_return_value', - '_NonCallableMock__get_side_effect', - '_NonCallableMock__return_value_doc', - '_NonCallableMock__set_return_value', - '_NonCallableMock__set_side_effect', - '__call__', - '__class__', - ... - -Alternatively you can just use `vars(my_mock)` (instance members) and -`dir(type(my_mock))` (type members) to bypass the filtering irrespective of -`mock.FILTER_DIR`. - - -mock_open -========= - -.. function:: mock_open(mock=None, read_data=None) - - A helper function to create a mock to replace the use of `open`. It works - for `open` called directly or used as a context manager. - - The `mock` argument is the mock object to configure. If `None` (the - default) then a `MagicMock` will be created for you, with the API limited - to methods or attributes available on standard file handles. - - `read_data` is a string for the `read` method of the file handle to return. - This is an empty string by default. - -Using `open` as a context manager is a great way to ensure your file handles -are closed properly and is becoming common:: - - with open('/some/path', 'w') as f: - f.write('something') - -The issue is that even if you mock out the call to `open` it is the -*returned object* that is used as a context manager (and has `__enter__` and -`__exit__` called). - -Mocking context managers with a :class:`MagicMock` is common enough and fiddly -enough that a helper function is useful. - -.. doctest:: - - >>> from mock import mock_open - >>> m = mock_open() - >>> with patch('__main__.open', m, create=True): - ... with open('foo', 'w') as h: - ... h.write('some stuff') - ... - >>> m.mock_calls - [call('foo', 'w'), - call().__enter__(), - call().write('some stuff'), - call().__exit__(None, None, None)] - >>> m.assert_called_once_with('foo', 'w') - >>> handle = m() - >>> handle.write.assert_called_once_with('some stuff') - -And for reading files: - -.. doctest:: - - >>> with patch('__main__.open', mock_open(read_data='bibble'), create=True) as m: - ... with open('foo') as h: - ... result = h.read() - ... - >>> m.assert_called_once_with('foo') - >>> assert result == 'bibble' - - -.. _auto-speccing: - -Autospeccing -============ - -Autospeccing is based on the existing `spec` feature of mock. It limits the -api of mocks to the api of an original object (the spec), but it is recursive -(implemented lazily) so that attributes of mocks only have the same api as -the attributes of the spec. In addition mocked functions / methods have the -same call signature as the original so they raise a `TypeError` if they are -called incorrectly. - -Before I explain how auto-speccing works, here's why it is needed. - -`Mock` is a very powerful and flexible object, but it suffers from two flaws -when used to mock out objects from a system under test. One of these flaws is -specific to the `Mock` api and the other is a more general problem with using -mock objects. - -First the problem specific to `Mock`. `Mock` has two assert methods that are -extremely handy: :meth:`~Mock.assert_called_with` and -:meth:`~Mock.assert_called_once_with`. - -.. doctest:: - - >>> mock = Mock(name='Thing', return_value=None) - >>> mock(1, 2, 3) - >>> mock.assert_called_once_with(1, 2, 3) - >>> mock(1, 2, 3) - >>> mock.assert_called_once_with(1, 2, 3) - Traceback (most recent call last): - ... - AssertionError: Expected to be called once. Called 2 times. - -Because mocks auto-create attributes on demand, and allow you to call them -with arbitrary arguments, if you misspell one of these assert methods then -your assertion is gone: - -.. code-block:: pycon - - >>> mock = Mock(name='Thing', return_value=None) - >>> mock(1, 2, 3) - >>> mock.assret_called_once_with(4, 5, 6) - -Your tests can pass silently and incorrectly because of the typo. - -The second issue is more general to mocking. If you refactor some of your -code, rename members and so on, any tests for code that is still using the -*old api* but uses mocks instead of the real objects will still pass. This -means your tests can all pass even though your code is broken. - -Note that this is another reason why you need integration tests as well as -unit tests. Testing everything in isolation is all fine and dandy, but if you -don't test how your units are "wired together" there is still lots of room -for bugs that tests might have caught. - -`mock` already provides a feature to help with this, called speccing. If you -use a class or instance as the `spec` for a mock then you can only access -attributes on the mock that exist on the real class: - -.. doctest:: - - >>> import urllib2 - >>> mock = Mock(spec=urllib2.Request) - >>> mock.assret_called_with - Traceback (most recent call last): - ... - AttributeError: Mock object has no attribute 'assret_called_with' - -The spec only applies to the mock itself, so we still have the same issue -with any methods on the mock: - -.. code-block:: pycon - - >>> mock.has_data() - <mock.Mock object at 0x...> - >>> mock.has_data.assret_called_with() - -Auto-speccing solves this problem. You can either pass `autospec=True` to -`patch` / `patch.object` or use the `create_autospec` function to create a -mock with a spec. If you use the `autospec=True` argument to `patch` then the -object that is being replaced will be used as the spec object. Because the -speccing is done "lazily" (the spec is created as attributes on the mock are -accessed) you can use it with very complex or deeply nested objects (like -modules that import modules that import modules) without a big performance -hit. - -Here's an example of it in use: - -.. doctest:: - - >>> import urllib2 - >>> patcher = patch('__main__.urllib2', autospec=True) - >>> mock_urllib2 = patcher.start() - >>> urllib2 is mock_urllib2 - True - >>> urllib2.Request - <MagicMock name='urllib2.Request' spec='Request' id='...'> - -You can see that `urllib2.Request` has a spec. `urllib2.Request` takes two -arguments in the constructor (one of which is `self`). Here's what happens if -we try to call it incorrectly: - -.. doctest:: - - >>> req = urllib2.Request() - Traceback (most recent call last): - ... - TypeError: <lambda>() takes at least 2 arguments (1 given) - -The spec also applies to instantiated classes (i.e. the return value of -specced mocks): - -.. doctest:: - - >>> req = urllib2.Request('foo') - >>> req - <NonCallableMagicMock name='urllib2.Request()' spec='Request' id='...'> - -`Request` objects are not callable, so the return value of instantiating our -mocked out `urllib2.Request` is a non-callable mock. With the spec in place -any typos in our asserts will raise the correct error: - -.. doctest:: - - >>> req.add_header('spam', 'eggs') - <MagicMock name='urllib2.Request().add_header()' id='...'> - >>> req.add_header.assret_called_with - Traceback (most recent call last): - ... - AttributeError: Mock object has no attribute 'assret_called_with' - >>> req.add_header.assert_called_with('spam', 'eggs') - -In many cases you will just be able to add `autospec=True` to your existing -`patch` calls and then be protected against bugs due to typos and api -changes. - -As well as using `autospec` through `patch` there is a -:func:`create_autospec` for creating autospecced mocks directly: - -.. doctest:: - - >>> import urllib2 - >>> mock_urllib2 = create_autospec(urllib2) - >>> mock_urllib2.Request('foo', 'bar') - <NonCallableMagicMock name='mock.Request()' spec='Request' id='...'> - -This isn't without caveats and limitations however, which is why it is not -the default behaviour. In order to know what attributes are available on the -spec object, autospec has to introspect (access attributes) the spec. As you -traverse attributes on the mock a corresponding traversal of the original -object is happening under the hood. If any of your specced objects have -properties or descriptors that can trigger code execution then you may not be -able to use autospec. On the other hand it is much better to design your -objects so that introspection is safe [#]_. - -A more serious problem is that it is common for instance attributes to be -created in the `__init__` method and not to exist on the class at all. -`autospec` can't know about any dynamically created attributes and restricts -the api to visible attributes. - -.. doctest:: - - >>> class Something(object): - ... def __init__(self): - ... self.a = 33 - ... - >>> with patch('__main__.Something', autospec=True): - ... thing = Something() - ... thing.a - ... - Traceback (most recent call last): - ... - AttributeError: Mock object has no attribute 'a' - -There are a few different ways of resolving this problem. The easiest, but -not necessarily the least annoying, way is to simply set the required -attributes on the mock after creation. Just because `autospec` doesn't allow -you to fetch attributes that don't exist on the spec it doesn't prevent you -setting them: - -.. doctest:: - - >>> with patch('__main__.Something', autospec=True): - ... thing = Something() - ... thing.a = 33 - ... - -There is a more aggressive version of both `spec` and `autospec` that *does* -prevent you setting non-existent attributes. This is useful if you want to -ensure your code only *sets* valid attributes too, but obviously it prevents -this particular scenario: - -.. doctest:: - - >>> with patch('__main__.Something', autospec=True, spec_set=True): - ... thing = Something() - ... thing.a = 33 - ... - Traceback (most recent call last): - ... - AttributeError: Mock object has no attribute 'a' - -Probably the best way of solving the problem is to add class attributes as -default values for instance members initialised in `__init__`. Note that if -you are only setting default attributes in `__init__` then providing them via -class attributes (shared between instances of course) is faster too. e.g. - -.. code-block:: python - - class Something(object): - a = 33 - -This brings up another issue. It is relatively common to provide a default -value of `None` for members that will later be an object of a different type. -`None` would be useless as a spec because it wouldn't let you access *any* -attributes or methods on it. As `None` is *never* going to be useful as a -spec, and probably indicates a member that will normally of some other type, -`autospec` doesn't use a spec for members that are set to `None`. These will -just be ordinary mocks (well - `MagicMocks`): - -.. doctest:: - - >>> class Something(object): - ... member = None - ... - >>> mock = create_autospec(Something) - >>> mock.member.foo.bar.baz() - <MagicMock name='mock.member.foo.bar.baz()' id='...'> - -If modifying your production classes to add defaults isn't to your liking -then there are more options. One of these is simply to use an instance as the -spec rather than the class. The other is to create a subclass of the -production class and add the defaults to the subclass without affecting the -production class. Both of these require you to use an alternative object as -the spec. Thankfully `patch` supports this - you can simply pass the -alternative object as the `autospec` argument: - -.. doctest:: - - >>> class Something(object): - ... def __init__(self): - ... self.a = 33 - ... - >>> class SomethingForTest(Something): - ... a = 33 - ... - >>> p = patch('__main__.Something', autospec=SomethingForTest) - >>> mock = p.start() - >>> mock.a - <NonCallableMagicMock name='Something.a' spec='int' id='...'> - -.. note:: - - An additional limitation (currently) with `autospec` is that unbound - methods on mocked classes *don't* take an "explicit self" as the first - argument - so this usage will fail with `autospec`. - - .. doctest:: - - >>> class Foo(object): - ... def foo(self): - ... pass - ... - >>> Foo.foo(Foo()) - >>> MockFoo = create_autospec(Foo) - >>> MockFoo.foo(MockFoo()) - Traceback (most recent call last): - ... - TypeError: <lambda>() takes exactly 1 argument (2 given) - - The reason is that its very hard to tell the difference between functions, - unbound methods and staticmethods across Python 2 & 3 and the alternative - implementations. This restriction may be fixed in future versions. - - ------- - -.. [#] This only applies to classes or already instantiated objects. Calling - a mocked class to create a mock instance *does not* create a real instance. - It is only attribute lookups - along with calls to `dir` - that are done. A - way round this problem would have been to use `getattr_static - <http://docs.python.org/dev/library/inspect.html#inspect.getattr_static>`_, - which can fetch attributes without triggering code execution. Descriptors - like `classmethod` and `staticmethod` *need* to be fetched correctly though, - so that their signatures can be mocked correctly. http://git-wip-us.apache.org/repos/asf/incubator-atlas/blob/c219798b/src/test/mock/docs/index.txt ---------------------------------------------------------------------- diff --git a/src/test/mock/docs/index.txt b/src/test/mock/docs/index.txt deleted file mode 100644 index fe89925..0000000 --- a/src/test/mock/docs/index.txt +++ /dev/null @@ -1,411 +0,0 @@ -==================================== - Mock - Mocking and Testing Library -==================================== - -.. currentmodule:: mock - -:Author: `Michael Foord - <http://www.voidspace.org.uk/python/weblog/index.shtml>`_ -:Version: |release| -:Date: 2012/10/07 -:Homepage: `Mock Homepage`_ -:Download: `Mock on PyPI`_ -:Documentation: `PDF Documentation - <http://www.voidspace.org.uk/downloads/mock-1.0.1.pdf>`_ -:License: `BSD License`_ -:Support: `Mailing list (testing-in-pyt...@lists.idyll.org) - <http://lists.idyll.org/listinfo/testing-in-python>`_ -:Issue tracker: `Google code project - <http://code.google.com/p/mock/issues/list>`_ - -.. _Mock Homepage: http://www.voidspace.org.uk/python/mock/ -.. _BSD License: http://www.voidspace.org.uk/python/license.shtml - - -.. currentmodule:: mock - -.. module:: mock - :synopsis: Mock object and testing library. - -.. index:: introduction - -mock is a library for testing in Python. It allows you to replace parts of -your system under test with mock objects and make assertions about how they -have been used. - -mock is now part of the Python standard library, available as `unittest.mock -<http://docs.python.org/py3k/library/unittest.mock.html#module-unittest.mock>`_ -in Python 3.3 onwards. - -mock provides a core :class:`Mock` class removing the need to create a host -of stubs throughout your test suite. After performing an action, you can make -assertions about which methods / attributes were used and arguments they were -called with. You can also specify return values and set needed attributes in -the normal way. - -Additionally, mock provides a :func:`patch` decorator that handles patching -module and class level attributes within the scope of a test, along with -:const:`sentinel` for creating unique objects. See the `quick guide`_ for -some examples of how to use :class:`Mock`, :class:`MagicMock` and -:func:`patch`. - -Mock is very easy to use and is designed for use with -`unittest <http://pypi.python.org/pypi/unittest2>`_. Mock is based on -the 'action -> assertion' pattern instead of `'record -> replay'` used by many -mocking frameworks. - -mock is tested on Python versions 2.4-2.7, Python 3 plus the latest versions of -Jython and PyPy. - - -.. testsetup:: - - class ProductionClass(object): - def method(self, *args): - pass - - module = sys.modules['module'] = ProductionClass - ProductionClass.ClassName1 = ProductionClass - ProductionClass.ClassName2 = ProductionClass - - - -API Documentation -================= - -.. toctree:: - :maxdepth: 2 - - mock - patch - helpers - sentinel - magicmock - - -User Guide -========== - -.. toctree:: - :maxdepth: 2 - - getting-started - examples - compare - changelog - - -.. index:: installing - -Installing -========== - -The current version is |release|. Mock is stable and widely used. If you do -find any bugs, or have suggestions for improvements / extensions -then please contact us. - -* `mock on PyPI <http://pypi.python.org/pypi/mock>`_ -* `mock documentation as PDF - <http://www.voidspace.org.uk/downloads/mock-1.0.1.pdf>`_ -* `Google Code Home & Mercurial Repository <http://code.google.com/p/mock/>`_ - -.. index:: repository -.. index:: hg - -You can checkout the latest development version from the Google Code Mercurial -repository with the following command: - - ``hg clone https://mock.googlecode.com/hg/ mock`` - - -.. index:: pip -.. index:: easy_install -.. index:: setuptools - -If you have pip, setuptools or distribute you can install mock with: - - | ``easy_install -U mock`` - | ``pip install -U mock`` - -Alternatively you can download the mock distribution from PyPI and after -unpacking run: - - ``python setup.py install`` - - -Quick Guide -=========== - -:class:`Mock` and :class:`MagicMock` objects create all attributes and -methods as you access them and store details of how they have been used. You -can configure them, to specify return values or limit what attributes are -available, and then make assertions about how they have been used: - -.. doctest:: - - >>> from mock import MagicMock - >>> thing = ProductionClass() - >>> thing.method = MagicMock(return_value=3) - >>> thing.method(3, 4, 5, key='value') - 3 - >>> thing.method.assert_called_with(3, 4, 5, key='value') - -:attr:`side_effect` allows you to perform side effects, including raising an -exception when a mock is called: - -.. doctest:: - - >>> mock = Mock(side_effect=KeyError('foo')) - >>> mock() - Traceback (most recent call last): - ... - KeyError: 'foo' - - >>> values = {'a': 1, 'b': 2, 'c': 3} - >>> def side_effect(arg): - ... return values[arg] - ... - >>> mock.side_effect = side_effect - >>> mock('a'), mock('b'), mock('c') - (1, 2, 3) - >>> mock.side_effect = [5, 4, 3, 2, 1] - >>> mock(), mock(), mock() - (5, 4, 3) - -Mock has many other ways you can configure it and control its behaviour. For -example the `spec` argument configures the mock to take its specification -from another object. Attempting to access attributes or methods on the mock -that don't exist on the spec will fail with an `AttributeError`. - -The :func:`patch` decorator / context manager makes it easy to mock classes or -objects in a module under test. The object you specify will be replaced with a -mock (or other object) during the test and restored when the test ends: - -.. doctest:: - - >>> from mock import patch - >>> @patch('module.ClassName2') - ... @patch('module.ClassName1') - ... def test(MockClass1, MockClass2): - ... module.ClassName1() - ... module.ClassName2() - - ... assert MockClass1 is module.ClassName1 - ... assert MockClass2 is module.ClassName2 - ... assert MockClass1.called - ... assert MockClass2.called - ... - >>> test() - -.. note:: - - When you nest patch decorators the mocks are passed in to the decorated - function in the same order they applied (the normal *python* order that - decorators are applied). This means from the bottom up, so in the example - above the mock for `module.ClassName1` is passed in first. - - With `patch` it matters that you patch objects in the namespace where they - are looked up. This is normally straightforward, but for a quick guide - read :ref:`where to patch <where-to-patch>`. - -As well as a decorator `patch` can be used as a context manager in a with -statement: - -.. doctest:: - - >>> with patch.object(ProductionClass, 'method', return_value=None) as mock_method: - ... thing = ProductionClass() - ... thing.method(1, 2, 3) - ... - >>> mock_method.assert_called_once_with(1, 2, 3) - - -There is also :func:`patch.dict` for setting values in a dictionary just -during a scope and restoring the dictionary to its original state when the test -ends: - -.. doctest:: - - >>> foo = {'key': 'value'} - >>> original = foo.copy() - >>> with patch.dict(foo, {'newkey': 'newvalue'}, clear=True): - ... assert foo == {'newkey': 'newvalue'} - ... - >>> assert foo == original - -Mock supports the mocking of Python :ref:`magic methods <magic-methods>`. The -easiest way of using magic methods is with the :class:`MagicMock` class. It -allows you to do things like: - -.. doctest:: - - >>> mock = MagicMock() - >>> mock.__str__.return_value = 'foobarbaz' - >>> str(mock) - 'foobarbaz' - >>> mock.__str__.assert_called_with() - -Mock allows you to assign functions (or other Mock instances) to magic methods -and they will be called appropriately. The `MagicMock` class is just a Mock -variant that has all of the magic methods pre-created for you (well, all the -useful ones anyway). - -The following is an example of using magic methods with the ordinary Mock -class: - -.. doctest:: - - >>> mock = Mock() - >>> mock.__str__ = Mock(return_value='wheeeeee') - >>> str(mock) - 'wheeeeee' - -For ensuring that the mock objects in your tests have the same api as the -objects they are replacing, you can use :ref:`auto-speccing <auto-speccing>`. -Auto-speccing can be done through the `autospec` argument to patch, or the -:func:`create_autospec` function. Auto-speccing creates mock objects that -have the same attributes and methods as the objects they are replacing, and -any functions and methods (including constructors) have the same call -signature as the real object. - -This ensures that your mocks will fail in the same way as your production -code if they are used incorrectly: - -.. doctest:: - - >>> from mock import create_autospec - >>> def function(a, b, c): - ... pass - ... - >>> mock_function = create_autospec(function, return_value='fishy') - >>> mock_function(1, 2, 3) - 'fishy' - >>> mock_function.assert_called_once_with(1, 2, 3) - >>> mock_function('wrong arguments') - Traceback (most recent call last): - ... - TypeError: <lambda>() takes exactly 3 arguments (1 given) - -`create_autospec` can also be used on classes, where it copies the signature of -the `__init__` method, and on callable objects where it copies the signature of -the `__call__` method. - - -.. index:: references -.. index:: articles - -References -========== - -Articles, blog entries and other stuff related to testing with Mock: - -* `Imposing a No DB Discipline on Django unit tests - <https://github.com/carljm/django-testing-slides/blob/master/models/30_no_database.md>`_ -* `mock-django: tools for mocking the Django ORM and models - <https://github.com/dcramer/mock-django>`_ -* `PyCon 2011 Video: Testing with mock <https://blip.tv/file/4881513>`_ -* `Mock objects in Python - <http://noopenblockers.com/2012/01/06/mock-objects-in-python/>`_ -* `Python: Injecting Mock Objects for Powerful Testing - <http://blueprintforge.com/blog/2012/01/08/python-injecting-mock-objects-for-powerful-testing/>`_ -* `Python Mock: How to assert a substring of logger output - <http://www.michaelpollmeier.com/python-mock-how-to-assert-a-substring-of-logger-output/>`_ -* `Mocking Django <http://www.mattjmorrison.com/2011/09/mocking-django.html>`_ -* `Mocking dates and other classes that can't be modified - <http://williamjohnbert.com/2011/07/how-to-unit-testing-in-django-with-mocking-and-patching/>`_ -* `Mock recipes <http://konryd.blogspot.com/2010/06/mock-recipies.html>`_ -* `Mockity mock mock - some love for the mock module - <http://konryd.blogspot.com/2010/05/mockity-mock-mock-some-love-for-mock.html>`_ -* `Coverage and Mock (with django) - <http://mattsnider.com/python/mock-and-coverage/>`_ -* `Python Unit Testing with Mock <http://www.insomnihack.com/?p=194>`_ -* `Getting started with Python Mock - <http://myadventuresincoding.wordpress.com/2011/02/26/python-python-mock-cheat-sheet/>`_ -* `Smart Parameter Checks with mock - <http://tobyho.com/2011/03/24/smart-parameter-checks-in/>`_ -* `Python mock testing techniques and tools - <http://agiletesting.blogspot.com/2009/07/python-mock-testing-techniques-and.html>`_ -* `How To Test Django Template Tags - <http://techblog.ironfroggy.com/2008/10/how-to-test.html>`_ -* `A presentation on Unit Testing with Mock - <http://pypap.blogspot.com/2008/10/newbie-nugget-unit-testing-with-mock.html>`_ -* `Mocking with Django and Google AppEngine - <http://michael-a-nelson.blogspot.com/2008/09/mocking-with-django-and-google-app.html>`_ - - -.. index:: tests -.. index:: unittest2 - -Tests -===== - -Mock uses `unittest2 <http://pypi.python.org/pypi/unittest2>`_ for its own -test suite. In order to run it, use the `unit2` script that comes with -`unittest2` module on a checkout of the source repository: - - `unit2 discover` - -If you have `setuptools <http://pypi.python.org/pypi/distribute>`_ as well as -unittest2 you can run: - - ``python setup.py test`` - -On Python 3.2 you can use ``unittest`` module from the standard library. - - ``python3.2 -m unittest discover`` - -.. index:: Python 3 - -On Python 3 the tests for unicode are skipped as they are not relevant. On -Python 2.4 tests that use the with statements are skipped as the with statement -is invalid syntax on Python 2.4. - - -.. index:: older versions - -Older Versions -============== - -Documentation for older versions of mock: - -* `mock 0.8 <http://www.voidspace.org.uk/python/mock/0.8/>`_ -* `mock 0.7 <http://www.voidspace.org.uk/python/mock/0.7/>`_ -* `mock 0.6 <http://www.voidspace.org.uk/python/mock/0.6.0/>`_ - -Docs from the in-development version of `mock` can be found at -`mock.readthedocs.org <http://mock.readthedocs.org>`_. - - -Terminology -=========== - -Terminology for objects used to replace other ones can be confusing. Terms -like double, fake, mock, stub, and spy are all used with varying meanings. - -In `classic mock terminology -<http://xunitpatterns.com/Mocks,%20Fakes,%20Stubs%20and%20Dummies.html>`_ -:class:`mock.Mock` is a `spy <http://xunitpatterns.com/Test%20Spy.html>`_ that -allows for *post-mortem* examination. This is what I call the "action -> -assertion" [#]_ pattern of testing. - -I'm not however a fan of this "statically typed mocking terminology" -promulgated by `Martin Fowler -<http://martinfowler.com/articles/mocksArentStubs.html>`_. It confuses usage -patterns with implementation and prevents you from using natural terminology -when discussing mocking. - -I much prefer duck typing, if an object used in your test suite looks like a -mock object and quacks like a mock object then it's fine to call it a mock, no -matter what the implementation looks like. - -This terminology is perhaps more useful in less capable languages where -different usage patterns will *require* different implementations. -`mock.Mock()` is capable of being used in most of the different roles -described by Fowler, except (annoyingly / frustratingly / ironically) a Mock -itself! - -How about a simpler definition: a "mock object" is an object used to replace a -real one in a system under test. - -.. [#] This pattern is called "AAA" by some members of the testing community; - "Arrange - Act - Assert".
