如何在每次测试中更改笑话模拟函数的返回值? [英] how to change jest mock function return value in each test?

问题描述

我的组件测试文件中有一个类似这样的模拟模块

I have a mock module like this in my component test file

  jest.mock('../../../magic/index', () => ({
    navigationEnabled: () => true,
    guidanceEnabled: () => true
  }));

这些函数将在我的组件的渲染函数中调用，以隐藏和显示某些特定功能.

these functions will be called in render function of my component to hide and show some specific feature.

我想对这些模拟函数的返回值的不同组合进行快照.

I want to take a snapshot on different combinations of the return value of those mock functions.

假设我有一个这样的测试用例

for suppose I have a test case like this

 it('RowListItem should not render navigation and guidance options', () => {
    const wrapper = shallow(
      <RowListItem type="regularList" {...props} />
    );
    expect(enzymeToJson(wrapper)).toMatchSnapshot();
  });

要运行此测试用例，我想动态地将模拟模块函数的返回值更改为false

to run this test case I want to change the mock module functions return values to false like this dynamically

jest.mock('../../../magic/index', () => ({
    navigationEnabled: () => false,
    guidanceEnabled: () => false
  }));

因为我已经一次导入了RowListItem组件，所以我的模拟模块不会再次重新导入.所以它不会改变.我该如何解决?

because i am importing RowListItem component already once so my mock module wont re import again. so it wont change. how can i solve this ?

推荐答案

您可以模拟该模块，以便它返回间谍并将其导入到您的测试中:

You can mock the module so it returns spies and import it into your test:

import {navigationEnabled, guidanceEnabled} from '../../../magic/index'

jest.mock('../../../magic/index', () => ({
    navigationEnabled: jest.fn(),
    guidanceEnabled: jest.fn()
}));

然后稍后您可以使用mockImplementation

navigationEnabled.mockImplementation(()=> true)
//or
navigationEnabled.mockReturnValueOnce(true);

并在下一个测试中

navigationEnabled.mockImplementation(()=> false)
//or
navigationEnabled.mockReturnValueOnce(false);

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