[英]Jest : mock constructor function
I'm having trouble trying to mock a constructor Function.我在尝试模拟构造函数时遇到问题。
Here is the main class that I want to test这是我要测试的主类
// main.js
import { Handler } from './handler/handler.js';
var lh = new Handler(windowAlias, documentAlias);
// rest of code
Here is how my Handler function looks.这是我的 Handler 函数的外观。 Im trying to mock this我试图嘲笑这个
//handler.js
export function Handler(windowAlias, documentAlias) {
this.windowAlias = windowAlias;
this.documentAlias = documentAlias;
this.attachEventListners = function(globalSet) {
// do something
};
}
And the test code:和测试代码:
// main.test.js
import { Handler } from 'handlers/handler'
describe('main script', () => {
it('test handler', () => {
jest.mock('handlers/handler', () => jest.fn())
const mockEventListner = jest.fn()
Handler.mockImplementation(() => ({mockEventListner}))
//call main.js
expect(mockEventListner).toBeCalledTimes(1);
})
I referred this stack overflow and tried but now Im getting error like _handler.Handler is not a constructor on the line that does new Handler().我提到了这个堆栈溢出并尝试过,但现在我收到错误,如 _handler.Handler is not a constructor on the line that do new Handler()。 How can I mock the new Handler call when its a constructor function当它是一个构造函数时,我如何模拟新的 Handler 调用
You could use jest.mock(moduleName, factory, options) to mock ./handler/handler.js
module and Handler
class manually.您可以使用jest.mock(moduleName, factory, options)手动模拟./handler/handler.js
模块和Handler
类。
Eg例如
main.js
: main.js
:
import { Handler } from './handler/handler.js';
const windowAlias = 'windowAlias';
const documentAlias = 'documentAlias';
var lh = new Handler(windowAlias, documentAlias);
handler/handler.js
: handler/handler.js
:
export function Handler(windowAlias, documentAlias) {
this.windowAlias = windowAlias;
this.documentAlias = documentAlias;
this.attachEventListners = function(globalSet) {
// do something
};
}
main.test.js
: main.test.js
:
import './main';
import { Handler } from './handler/handler.js';
jest.mock('./handler/handler.js', () => {
return { Handler: jest.fn() };
});
describe('64382021', () => {
it('should pass', async () => {
expect(Handler).toBeCalledWith('windowAlias', 'documentAlias');
});
});
unit test result:单元测试结果:
PASS src/stackoverflow/64382021/main.test.js
64382021
✓ should pass (6ms)
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 4.093s, estimated 10s
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