mock test example

mock_ex.py

# https://docs.python.org/3/library/unittest.mock.html
from unittest.mock import MagicMock, Mock
from nose.tools import assert_equal, raises, assert_true, assert_raises

class A():
    def __init__(self):
        self.item = 'item'

    def return_item(self, thing = None):
        if not thing:
            return(self.item)
        else:
            return(thing)

class TestA():
    def __init__(self):
        pass

    def test_return_item(self):
        # testing `MagicMock` for methods
        t = A()
        t.return_item = MagicMock(return_value = 3)

        assert_equal(t.return_item('item'),3) ## TRUE
        assert_equal(t.return_item(),3) ## TRUE