Question

所以，我正在尝试做表面上应该非常简单的事情...

我在下面定义了一些常量： ` //constants.js

module.exports = {
 MY_CONSTANT: "TEST"
}

` 我有一个要测试的文件，该文件具有这样的分支语句：

`

//file to test
//...

if(CONSTANTS.MY_CONSTANT === "TEST")
{...}
...

`

我有一个像这样的测试： `

//test


 it("Should do something when MY_CONSTANT === "TEST, () => {
    //This is fine as it is exported as TEST
    })


 it("Should do something else when MY_CONSTANT !== "TEST, () => {
    //This seems annoyingly difficult to get working...
    })

`

I've tried this -运气不好，它不会改变实际值

我尝试将常量导出更改为导出对象（无效）

我尝试在测试文件中为常量添加jest.mock（..），并在测试中取消模拟，而无需模拟它们。

我尝试在测试函数中添加一个jest.doMock（...），我需要更改该值。（以及jest.resetModules和其他要求）

我尝试将jest.doMock（...）添加到beforeEach的测试中（以及jest.resetModules和其他要求）

我真的很茫然...我要做的就是在测试运行前更改属性值

更新所以我已经提出了一些建议：

我现在在常量文件夹旁边有一个 mocks 文件夹它包含一个与实际常量文件相同名称的文件和一个自定义导出

然后我在测试中添加了jest.mock("../constants);。

然后我还在测试中添加了const funcImTesting = require("../../file").testFunction。

常量仍然保持不变并且测试失败

Answer 1

仅针对一个测试进行模拟：

https://jestjs.io/docs/en/manual-mocks

为每个测试提供一个模拟：

为您要模拟的模块创建一个jest.mock('./constants.js', () => ({ MY_CONSTANT: 'something fake' }));目录 adiacent
提供实施方式
在测试中致电__mocks__

https://jestjs.io/docs/en/manual-mocks#mocking-user-modules

Answer 2

我只是复制常量，并在每个测试用例之后分配它们。

const constants = require('./constants');
const original = {...constants};
afterEach(() => {
    Object.assign(constants, original);
});
test('test1', () => {
    constants.ABC = 'whatever';
});
test('test2', () => {
    // constants.ABC is set back to original
});

Answer 3

遵循doc on jest.doMock()的指导

config.js文件：

export const env = 'test';

myComponent.js文件：

import {env} from './config.js';

export const MyComponent = () => {
  if (env === 'prod') {
    return (<Text>Prod Env</Text>);
  } else if (env === 'test'){
    return (<Text>Test Env</Text>);
  } else {
    return (<Text>Dev Env</Text>);
  }
};

myComponent.test.js文件：

describe('Test MyComponent', () => {
  test('Test in prod env', () => {
    jest.doMock('./config', () => ({env: 'prod'}));
    const {MyComponent} = require('./myComponent.js');
    const myComp = mount(<MyComponent />);
    expect(myComp.find('Text')).toHaveText('Prod Env');
  });

  test('Test in test env', () => {
    jest.doMock('./config', () => ({env: 'test'}));
    const {MyComponent} = require('./myComponent.js');
    const myComp = mount(<MyComponent />);
    expect(myComp.find('Text')).toHaveText('Test Env');
  });

  test('Test in dev env', () => {
    jest.doMock('./config', () => ({env: 'dev'}));
    const {MyComponent} = require('./myComponent.js');
    const myComp = mount(<MyComponent />);
    expect(myComp.find('Text')).toHaveText('Dev Env');
  });
});

Answer 4

我通过在减速器中初始化ContstantsFile.js中的常量来解决此问题。并将其放在redux存储中。由于jest.mock无法模拟contstantsFile.js

https://stackoverflow.com/a/63064505/3412268
https://docs.aws.amazon.com/quicksight/latest/user/windowMax-function.html
https://docs.aws.amazon.com/quicksight/latest/user/countOver-function.html
https://docs.aws.amazon.com/quicksight/latest/user/level-aware-aggregations.html

现在，我们可以轻松地在test.jsx中模拟存储并将值提供给所需的常量。

constantsFile.js
-----------------
const MY_CONSTANTS = {
MY_CONSTANT1: "TEST",
MY_CONSTANT2: "BEST",
};
export defualt MY_CONSTANTS;

reducers/index.js
-----------------
import MY_CONST from "./constantsFile";

const initialState = {
...MY_CONST
}
export const AbcReducer = (state = initialState, action) => {.....}

ABC.jsx
------------
import { useSelector } from 'react-redux';
const ABC = () => {
const const1 = useSelector(state) => state. AbcReducer. MY_CONSTANT1:
const const2 = useSelector(state) => state. AbcReducer. MY_CONSTANT2:
.......

现在，当测试运行时，它将始终从模拟存储中选择常量值。

Answer 5

导出要模拟的常量的文件：

// utils/deviceTypeUtils file
import DeviceInfo from 'react-native-device-info';

export const isTablet = DeviceInfo.isTablet();

在测试文件中，我用它来模拟常量isTablet：

// file: deviceTypeUtils.spec
const DeviceTypeUtilsMock = jest.requireMock('../utils/deviceTypeUtils');
jest.mock('../utils/deviceTypeUtils', () => ({
  isTablet: false,
}));

describe('mock const example', () => {
  it('mock const `isTablet` to the value `true`', () => {
    DeviceTypeUtilsMock.isTablet = true;
  });

  it('mock const `isTablet` to the value `false`', () => {
    DeviceTypeUtilsMock.isTablet = false;
  });
});

Answer 6

通过关注 https://mikeborozdin.com/post/changing-jest-mocks-between-tests/

上的帖子，我已经能够做类似的事情

这会创建一个模拟，然后为每个测试更改它。

import * as constants from './constants'

jest.mock('./constants', () => ({
  __esModule: true,
  MY_CONSTANT: 'SOME OTHER DEFAULT',
}))

it("Should do something when MY_CONSTANT === "TEST, () => {
  constant.MY_CONSTANT = 'TEST'
  expect(constant.MY_CONSTANT).toBe('TEST')
})

it("Should do something else when MY_CONSTANT !== "TEST, () => {
  constant.MY_CONSTANT = 'NOT A TEST'
  expect(constant.MY_CONSTANT).toBe('NOT A TEST')
})

如果您使用的是打字稿，则需要转换模拟以修改模拟值：

const mockConstants = constants as { MY_CONSTANT: string }
mockConstants.MY_CONSTANT = 'TEST'

开玩笑-模拟模块的常数属性以进行特定测试

6 个答案: