Assert a function method was not called using Mock

Question

I m using the Mock library to test my application  but I want to assert that some function was not called  Mock docs talk about methods like mock assert called with and mock assert called once with  but I didn t find anything like mock assert not called or something related to verify mock was NOT called   I could go with something like the following  though it doesn t seem cool nor pythonic   def test something        some actions     with patch  something   as my var          try                args are not important  func should never be called in this test             my var assert called with some  args          except AssertionError              pass    this error being raised means it s ok       other stuff   Any ideas how to accomplish this

User · Answer

You can check the called attribute  but if your assertion fails  the next thing you ll want to know is something about the unexpected call  so you may as well arrange for that information to be displayed from the start  Using unittest  you can check the contents of call args list instead   self assertItemsEqual my var call args list        When it fails  it gives a message like this    AssertionError  Element counts were not equal  First has 0  Second has 1   call  first argument   4

User · Answer

Though an old question  I would like to add that currently mock library  backport of unittest mock  supports assert not called method   Just upgrade yours   pip install mock --upgrade

User · Answer

With python  gt   3 5 you can use mock object assert not called

User · Answer

When you test using class inherits unittest TestCase you can simply use methods like    assertTrue assertFalse assertEqual   and similar  in python documentation you find the rest    In your example we can simply assert if mock method called property is False  which means that method was not called   import unittest from unittest import mock  import my module  class A unittest TestCase       def setUp self           self message    Method should not be called  Called  times  times         mock patch  my module method to mock       def test self  mock method           my module method to mock            self assertFalse mock method called                           self message format times mock method call count

User · Answer

Judging from other answers  no one except  rob-kennedy talked about the call args list   It s a powerful tool for that you can implement the exact contrary of MagicMock assert called with    call args list is a list of call objects  Each call object represents a call made on a mocked callable    gt  gt  gt  from unittest mock import MagicMock  gt  gt  gt  m   MagicMock    gt  gt  gt  m call args list     gt  gt  gt  m 42   lt MagicMock name  mock    id  139675158423872  gt   gt  gt  gt  m call args list  call 42    gt  gt  gt  m 42  30   lt MagicMock name  mock    id  139675158423872  gt   gt  gt  gt  m call args list  call 42   call 42  30     Consuming a call object is easy  since you can compare it with a tuple of length 2 where the first component is a tuple containing all the positional arguments of the related call  while the second component is a dictionary of the keyword arguments    gt  gt  gt    42     in m call args list True  gt  gt  gt  m 42  foo  bar    lt MagicMock name  mock    id  139675158423872  gt   gt  gt  gt    42      foo    bar    in m call args list True  gt  gt  gt  m foo  bar    lt MagicMock name  mock    id  139675158423872  gt   gt  gt  gt         foo    bar    in m call args list True   So  a way to address the specific problem of the OP is  def test something        with patch  something   as my var          assert   some  args    not in my var call args list   Note that this way  instead of just checking if a mocked callable has been called  via MagicMock called  you can now check if it has been called with a specific set of arguments   That s useful  Say you want to test a function that takes a list and call another function  compute    for each of the value of the list only if they satisfy a specific condition   You can now mock compute  and test if it has been called on some value but not on others

User · Answer

This should work for your case   assert not my var called   method should not have been called    Sample    gt  gt  gt  mock Mock    gt  gt  gt  mock a    lt Mock name  mock a    id  4349129872  gt   gt  gt  gt  assert not mock b called   b was called and should not have been   gt  gt  gt  assert not mock a called   a was called and should not have been  Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt  AssertionError  a was called and should not have been

[python] Assert a function/method was not called using Mock

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