如何窥探类构造函数的玩笑? [英] How to spy on a class constructor jest?

问题描述

export class Foo {
    public static bar() {
        doSomething();
    }

    constructor(paramA, paramB) {

    } 
}

对于类中的方法，我们可以使用jest.spyOn(Foo, 'bar') 监视方法.构造函数呢?我们如何监视对象是如何实例化的?

For a method in a class, we can use jest.spyOn(Foo, 'bar') to spy on the method. How about constructor? How do we spy how the object is instantiated?

推荐答案

@gillyb 是对的，只是忘了mock" Foo 模块

@gillyb is right just forgot to "mock" the Foo module

// Foo.js
export class Foo {
    public static bar() {
        doSomething();
    }

    constructor(paramA, paramB) {

    } 
}

// Foo.spec.js
import Foo from './Foo.js';
jest.mock('./Foo.js');

it('test something...', () => {
    // Assuming we did something that called our constructor
    expect(Foo).toHaveBeenCalledTimes(1);
});

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