整个测试会话的模拟补丁

Question

tl;dr 如何让

mock.patch

持续整个测试会话，而不是仅在

@classmethod

范围或函数范围内？我想

模拟补丁

一个类方法。但是，我想在每个测试中运行 with 一次而不是一次。

目前我必须打电话

patch.object

两次

patch.object

但是，我只想打一次

class MyClass():
    @classmethod
    def print_hello(cls):
        print("hello from the real MyClass.print_hello")

    def do_something(self):
        pass


def mock_print_hello(_cls):
    print("hello from the patched mock_print_hello")


class TestMyClass(unittest.TestCase):
    def test_init(self):
        with mock.patch.object(MyClass, "print_hello", new_callable=mock_print_hello) as patch:
            MyClass.print_hello()
            MyClass()

    def test_do_something(self):
        with mock.patch.object(MyClass, "print_hello", new_callable=mock_print_hello) as patch:
            MyClass.print_hello()
            MyClass().do_something()

一次：

patch.object

实际上，在

class MyClass():
    @classmethod
    def print_hello(cls) :
        print("hello from the real MyClass.print_hello")

    def do_something(self):
        pass


def mock_print_hello(_cls):
    print("hello from the patched mock_print_hello")


class TestMyClass(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        # this patch will not remain after setUpClass returns
        patch = mock.patch.object(MyClass, "print_hello", new_callable=mock_print_hello)

    def test_init(self):
        # this calls the real MyClass.print_hello, not mock_print_hello
        MyClass.print_hello()
        MyClass()

    def test_do_something(self):
        # this calls the real MyClass.print_hello, not mock_print_hello
        MyClass.print_hello()
        MyClass().do_something()

内修补

MyClass.new

不会持续超出功能范围。换句话说，

setUpClass

和

test_init

不调用

test_do_something

，它们调用

mock_print_hello

。我怎样才能让模拟补丁超出一个函数的范围？

Answer 1

start

。仅调用 MyClass.print_hello 或

patch

返回修补程序对象，它不会开始修补。由于您无法在设置代码中使用装饰器或上下文管理器，因此您必须在相应的 setUp/tearDown 方法中启动/停止修补程序：

patch.object

如果您需要修补整个模块，您可以在相应的模块功能中执行相同的操作：

class TestMyClass(unittest.TestCase):
    patcher = None

    @classmethod
    def setUpClass(cls):
        cls.patcher = mock.patch.object(MyClass, "print_hello", new_callable=mock_print_hello)
        cls.patcher.start()

    @classmethod
    def tearDownClass(cls):
        cls.patcher.stop()

顺便说一句，如果您要使用 

patcher = None

def setUpModule():
    global patcher
    patcher = mock.patch.object(...)
    patcher.start()

def tearDownModule():
    patcher.stop()

而不是

pytest

，也可以使用固定装置中的上下文管理器来完成：unittest

或在模块情况下：

class MyClassTest:
    @pytest.fixture(scope="class", autouse=True)
    def setup(self):
        with mock.patch.object(MyClass, "print_hello", new_callable=mock_print_hello):
            yield