Mocking a function that is invoked twice with different arguments

Question

Suppose I have the following function:

def function_to_test(context):
    list_of_invocations = [ func('arg%s' % number) for number in [1,2]]
    email_one = list_of_invocations[0].render(context)
    email_two = list_of_invocations[1].render(context)
    instance = class_to_mock(email_one, arg_1, arg_2)  
    instance.method_for_class(email_two, 'text/html')
    instance.send()

@mock.patch('app.foo.class_to_mock')
@mock.patch('app.foo.func')
def test_render_and_send_email(self, func_mock, mock_to_class):
    render_method = mock.Mock()
    render_method.return_value = mock.Mock()

    class_method = mock.Mock()
    class_method.return_value = mock.Mock()

    func_mock.return_value = mock.MagicMock(render=render_method)
    mock_to_class.return_value = mock.Magic(method_for_class=class_method)
    function_to_test('context goes heres')
    self.assertEqual(func_mock.call_count, 2)
    self.assertEqual(render_method.call_count, 2)
    self.assertEqual(mock_to_class.call_count, 1)
    self.assertEqual(method_class.call_count,1)

I am attempting to test this function using mocks, but I am having trouble deciding on how to test this. Two options that come to mind are using side_effector assert_has_calls. Here is the run down of what I am attempting to do.

I want to make sure that func is called twice. (Done)
I want to create a mock for each of the func invocations (Not Done)
I want to make sure that render is called twice. (Done)
I want to ensure that class_to_mock is called with email_one which is I need a mock for email_one and email_two. (Not Done)

The test would be something like this

`mock_to_class.assert_called_once_with(*MOCK EMAIL ONE*,'one', 'two')`

I want the same for '''method_for_class''' that would look like this (Not Done):

class_method.assert_called_once_with(*MOCK EMAIL TWO*, 'text/html')

Hopefully that makes sense. Basically, I need the two different invocations from func to make sure there arguments in class_to_mock and method_for_class.

score 2 · Accepted Answer · answered Jan 13 '16 at 22:30

You can use the new attribute in @patch.object:

email_one=Mock()
email_two=Mock()

func_call_count = 0
def my_func_mock():
    global func_call_count
    func_call_count += 1

    if func_call_count == 1:
        do_invocation_1()

    if func_call_count == 2:
        do_invocation_2()

def do_invocation_1():
    return [email_one, email_two]

def do_invocation_2():
    return [email_one, email_two]

@mock.patch('app.foo.class_to_mock')
@mock.patch('app.foo.func', new=my_func_mock)
def test_render_and_send_email(self, func_mock, mock_to_class):
    render_method = mock.Mock()
    render_method.return_value = mock.Mock()

    class_method = mock.Mock()
    class_method.return_value = mock.Mock()

    func_mock.return_value = mock.MagicMock(render=render_method)
    mock_to_class.return_value = mock.Magic(method_for_class=class_method)
    function_to_test('context goes heres')
    self.assertEqual(func_call_count, 2) # Use the func_call_count instead
    self.assertEqual(render_method.call_count, 2)
    mock_to_class.assert_called_once_With(email_one, email_two) # Now you can assert it is called once with email_one & two
    self.assertEqual(method_class.call_count,1)

Mocking a function that is invoked twice with different arguments

1 Answers1