Mocking imported class in Python











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I am trying to mock a class which is called in a module which imports said class, which I want to test.



# application.py
from my_module.my_submodule import MyClass

def my_function(var1):
instance = MyClass()

instance.some_function(var1)


and my testing file



# test_application.py
import mock
import application

def test_my_function():
with mock.patch('my_module.my_submodule.MyClass') as MockClass:
application.my_function(var1)

MockClass.assert_called()


This gives an error saying MockClass was not called.



Now, by looking at this question: Why python mock patch doesn't work?, I was inspired to change the application.py import to this



# application.py
import my_module.my_submodule as mysub

def my_function(var1):
instance = mysub.MyClass()

instance.some_function(var1)


that is, I don't directly import the class that I want to mock in the test. Now it works.



My question is, if this is working as intended, or I am doing something wrong in the original way? Is it really necessary to always import modules like this, if I want to mock a class used in a module I want to test?










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    up vote
    0
    down vote

    favorite












    I am trying to mock a class which is called in a module which imports said class, which I want to test.



    # application.py
    from my_module.my_submodule import MyClass

    def my_function(var1):
    instance = MyClass()

    instance.some_function(var1)


    and my testing file



    # test_application.py
    import mock
    import application

    def test_my_function():
    with mock.patch('my_module.my_submodule.MyClass') as MockClass:
    application.my_function(var1)

    MockClass.assert_called()


    This gives an error saying MockClass was not called.



    Now, by looking at this question: Why python mock patch doesn't work?, I was inspired to change the application.py import to this



    # application.py
    import my_module.my_submodule as mysub

    def my_function(var1):
    instance = mysub.MyClass()

    instance.some_function(var1)


    that is, I don't directly import the class that I want to mock in the test. Now it works.



    My question is, if this is working as intended, or I am doing something wrong in the original way? Is it really necessary to always import modules like this, if I want to mock a class used in a module I want to test?










    share|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I am trying to mock a class which is called in a module which imports said class, which I want to test.



      # application.py
      from my_module.my_submodule import MyClass

      def my_function(var1):
      instance = MyClass()

      instance.some_function(var1)


      and my testing file



      # test_application.py
      import mock
      import application

      def test_my_function():
      with mock.patch('my_module.my_submodule.MyClass') as MockClass:
      application.my_function(var1)

      MockClass.assert_called()


      This gives an error saying MockClass was not called.



      Now, by looking at this question: Why python mock patch doesn't work?, I was inspired to change the application.py import to this



      # application.py
      import my_module.my_submodule as mysub

      def my_function(var1):
      instance = mysub.MyClass()

      instance.some_function(var1)


      that is, I don't directly import the class that I want to mock in the test. Now it works.



      My question is, if this is working as intended, or I am doing something wrong in the original way? Is it really necessary to always import modules like this, if I want to mock a class used in a module I want to test?










      share|improve this question













      I am trying to mock a class which is called in a module which imports said class, which I want to test.



      # application.py
      from my_module.my_submodule import MyClass

      def my_function(var1):
      instance = MyClass()

      instance.some_function(var1)


      and my testing file



      # test_application.py
      import mock
      import application

      def test_my_function():
      with mock.patch('my_module.my_submodule.MyClass') as MockClass:
      application.my_function(var1)

      MockClass.assert_called()


      This gives an error saying MockClass was not called.



      Now, by looking at this question: Why python mock patch doesn't work?, I was inspired to change the application.py import to this



      # application.py
      import my_module.my_submodule as mysub

      def my_function(var1):
      instance = mysub.MyClass()

      instance.some_function(var1)


      that is, I don't directly import the class that I want to mock in the test. Now it works.



      My question is, if this is working as intended, or I am doing something wrong in the original way? Is it really necessary to always import modules like this, if I want to mock a class used in a module I want to test?







      python testing






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      share|improve this question











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      share|improve this question










      asked Nov 22 at 14:35









      Kaspar H

      276




      276
























          1 Answer
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          down vote



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          Yes it is working as intended, but you patched the wrong target.
          Try patching application.MyClass.



          application is not using my_module.my_submodule.MyClass anywhere,
          but MyClass alias instead.






          share|improve this answer





















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            1 Answer
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            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted










            Yes it is working as intended, but you patched the wrong target.
            Try patching application.MyClass.



            application is not using my_module.my_submodule.MyClass anywhere,
            but MyClass alias instead.






            share|improve this answer

























              up vote
              1
              down vote



              accepted










              Yes it is working as intended, but you patched the wrong target.
              Try patching application.MyClass.



              application is not using my_module.my_submodule.MyClass anywhere,
              but MyClass alias instead.






              share|improve this answer























                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted






                Yes it is working as intended, but you patched the wrong target.
                Try patching application.MyClass.



                application is not using my_module.my_submodule.MyClass anywhere,
                but MyClass alias instead.






                share|improve this answer












                Yes it is working as intended, but you patched the wrong target.
                Try patching application.MyClass.



                application is not using my_module.my_submodule.MyClass anywhere,
                but MyClass alias instead.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 22 at 15:52









                progmatico

                1,7511512




                1,7511512






























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