Pytest：为什么我的模拟函数没有被调用？答案

【问题标题】：Pytest: Why is my mocked functions not called?Pytest：为什么我的模拟函数没有被调用？
【发布时间】：2020-08-31 18:45:17
【问题描述】：

我正在尝试为我的代码编写单元测试。但是我得到了没有调用模拟的断言错误。如何解决这个问题？

在我的code.py

from SDK import ManagementClient

def init_client():
    MGMT_CLIENT = ManagementClient(credentials) 
    # ManagementClient is an imported module, MGMT_CLIENT is a global variable
    

def add_db(ids):
    for id in ids:
        db_connection = MGMT_CLIENT.databases
        db_connection.database_operations.create()

在test.py


@pytest.fixture()
def database_operations_mock():
    with mock.patch("code.MGMT_CLIENT.databases") as database_operations_mock:
        yield database_operations_mock

@pytest.fixutre
def client_mock():
        with mock.patch("code.ManagementClient") as client_mock:
        yield client_mock


def test_add():
    # prepare test data
    ids_mock = ['1','2'] 
    # update global variable for code.py to run add_db() 
    code.MGMT_CLIENT = client_mock()  
    # run actual functions
    code.add_db(ids_mock)  
    assert database_operations_mock.call_count == len(ids_mock)

我收到了这个错误：

>       assert database_operations_mock.call_count == len(ids_mock)
E       assert 0 == 2
E         +0
E         -2

【问题讨论】：

标签： unit-testing pytest python-unittest

【解决方案1】：

您只需要第二个模拟。另外，我认为您不太了解对模拟的调用是如何工作的，调用计数对应于调用的方法，在您的情况下它是 db_connection.database_operations.create。此外，您不能从测试脚本更新实际 Python 脚本中的全局变量，Python 不能那样工作。如果我理解正确，您的代码应该如下所示。

def test_add(client_mock):
    # prepare test data
    ids_mock = ['1','2']
    # make the mock return itself when we call ManagementClient(credentials)
    # this will allow us to validate call counts
    client_mock.return_value = client_mock
    # since ManagementClient is mocked the `add_db` function should already call the mock
    code.add_db(ids_mock)
    # we have to check that `create` is being called
    assert client_mock.databases.database_operations.create == len(ids_mock)

【讨论】：