Checking call order across multiple mocks

Define a Mock manager and attach mocks to it via attach_mock(). Then check for the mock_calls:

@patch('module.a')
@patch('module.b')
@patch('module.c')
def test_main_routine(c, b, a):
    manager = Mock()
    manager.attach_mock(a, 'a')
    manager.attach_mock(b, 'b')
    manager.attach_mock(c, 'c')

    module.main_routine()

    expected_calls = [call.a('a'), call.b('b'), call.c('c')]
    assert manager.mock_calls == expected_calls

Just to test that it works, change the order of function calls in the main_routine() function add see that it throws AssertionError.

See more examples at Tracking order of calls and less verbose call assertions (link is dead; substitute: https://docs.python.org/3/library/unittest.mock.html#attaching-mocks-as-attributes)

Hope that helps.