pythonunit-testing

How to mock.patch a class imported in another module

I have a python class with such a module:

xy.py

from a.b import ClassA

class ClassB:
  def method_1():
    a = ClassA()
    a.method2()

then I have ClassA defined as:

b.py

from c import ClassC

class ClassA:
  def method2():
      c = ClassC()
      c.method3()

Now in this code, when writing test for xy.py I want to mock.patch ClassC, is there a way to achieve that in python?

obviously I tried:

mock.patch('a.b.ClassA.ClassC')

and

mock.patch('a.b.c.ClassC')

None of these worked.

Solution

  • You need to patch where ClassC is located so that's ClassC in b:

    mock.patch('b.ClassC')

    Or, in other words, ClassC is imported into module b and so that's the scope in which ClassC needs to be patched.