无法在python中使用unitest来模拟类方法

时间:2016-09-22 19:33:24

标签: python python-2.7 unit-testing mocking python-unittest

模块a.ClassA

class ClassA():
    def __init__(self,callingString):
        print callingString

    def functionInClassA(self,val):
        return val

模块b.ClassB

from a.ClassA import ClassA

class ClassB():
    def __init__(self,val):
        self.value=val

    def functionInsideClassB(self):
        obj=ClassA("Calling From Class B")
        value=obj.functionInClassA(self.value)

Python unittest

import unittest
from b.ClassB import ClassB
from mock import patch, Mock, PropertyMock,mock

class Test(unittest.TestCase):
    @patch('b.ClassB.ClassA',autospec = True)
    def _test_sample(self,classAmock):
        dummyMock=Mock()
        dummyMock.functionInClassA.return_value="mocking functionInClassA"
        classAmock.return_value=dummyMock

        obj=ClassB("dummy_val")
        obj.functionInsideClassB()

        assert dummyMock.functionInClassA.assert_called_once_with("dummy_val")

断言失败。我到底哪里错了?

1 个答案:

答案 0 :(得分:1)

您已分配到return_value两次:

classAmock.return_value=dummyMock
classAmock.return_value=Mock()

第二项任务完全取消了你设置dummyMock的工作;新的Mock实例未设置functionInClassA属性。

您不需要创建新的模拟对象;只需使用默认的return_value属性值:

class Test(unittest.TestCase):
    @patch('b.ClassB.ClassA', autospec=True)
    def test_sample(self, classAmock):
        instance = classAmock.return_value
        instance.functionInClassA.return_value = "mocking functionInClassA"

        obj = ClassB("dummy_val")
        obj.functionInsideClassB()

        instance.functionInClassA.assert_called_once_with("dummy_val")

需要断言assert_called_once_with()的返回值,因为它总是None(使你的额外assert失败,总是如此)。将断言留给assert_called_once_with()方法,它会根据需要提升。

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