javascript 模拟另一个文件中的函数 - Jest
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Mock a function from another file - Jest
提问by Dalvik
I am writing Unit test cases for my application. There is one function which is written in Utils section and Used in all files. I wanted to mock this Utils function whenever I need but I am unable to do so.
我正在为我的应用程序编写单元测试用例。有一个函数写在 Utils 部分并在所有文件中使用。我想在需要时模拟这个 Utils 函数，但我无法这样做。
Here is my code setup:
这是我的代码设置：
Utils.js
实用程序.js
> const getData = (name) => "Hello !!! " + name;
>
> const getContact = ()=> return Contacts.mobile;
>
> export {
> getData,
> getContact }
Login.js (Which uses Utils.js)
Login.js（使用Utils.js）
const welcomeMessage = (name) => {
return getData(name);
}
My Test file (Login.spec.js)
我的测试文件 (Login.spec.js)
import { getData } from '../../src/utils';
jest.mock('getData', () => jest.fn())
describe('User actions', () => {
it('should get username', () => {
const value = 'Hello !!! Jest';
expect(welcomeMessage('Jest')).toEqual(value);
});
});
When I run my test case then I am getting this error:
当我运行我的测试用例时，我收到此错误：
Cannot find module 'getData' from 'Login.spec.js'
I tried to find the solution on official Jest Documentation and on SO as well but couldn't found anything. I am unable to fix this error and mock this function.
我试图在官方 Jest 文档和 SO 上找到解决方案，但找不到任何东西。我无法修复此错误并模拟此功能。
回答by Khoa
The first argument of jest.mock(...)must be a module path:
的第一个参数jest.mock(...)必须是模块路径：
jest.mock('../../src/utils');
because the utilsmodule is your code, not a 3rd lib, so you must learn manual mock of jest:
https://facebook.github.io/jest/docs/en/manual-mocks.html
因为utils模块是你的代码，而不是第三个库，所以你必须学习手动模拟笑话：https:
//facebook.github.io/jest/docs/en/manual-mocks.html
if you had this file: src/utils.js
如果你有这个文件： src/utils.js
you can mock it by creating a file: src/__mocks__/utils.js
你可以通过创建一个文件来模拟它： src/__mocks__/utils.js
content of this file is the replication of the original but replace the implementation by getData = jest.fn()
此文件的内容是原始文件的复制，但将实现替换为 getData = jest.fn()
on you test file, just call: jest.mock('../../src/utils');at begin of file.
在您的测试文件上，只需调用：jest.mock('../../src/utils');在文件开头。
then when you're familiar with, you can call that function inside beforeEach()and call its counter jest.unmock('../../src/utils');insider afterEach()
然后当你熟悉了，你可以在里面调用那个函数beforeEach()并调用它的counter jest.unmock('../../src/utils');insiderafterEach()
An easy way to think about it is that:
一个简单的思考方式是：
when you call jest.mock('../../src/utils');, it means you tell jestthat:
当你打电话时jest.mock('../../src/utils');，这意味着你告诉jest：
hey if the running test meets the line
require('../../src/utils'), don't load it, let load../../src/__mocks__/utils.
嘿，如果运行测试符合行
require('../../src/utils')，不要加载它，让加载../../src/__mocks__/utils。
回答by Dan
another solution would fake this by doing something like:
另一种解决方案将通过执行以下操作来伪造：
window['getData'] = jest.fn();
