如何从beforeEach()中传递值进行测试?摩卡/柴 [英] How do I pass value from beforeEach() to test? Mocha/Chai

问题描述

如何将 dom 对象从我的beforeEach()函数传递到测试中?

How do I pass the dom object, from my beforeEach() function, to my tests?

例如:

describe('2) Key DOM elements exist', function() {

beforeEach(function(done){
    JSDOM.fromURL('http://localhost:3000/', ).then(dom => {
        this.hello = dom;
    });
    done();
  });

  it('a) Header element is present', function() {
        console.log(hello);
        const header = dom.window.document.getElementById('header');
        expect(header).to.exist;
 })
});

推荐答案

问题是 this 未绑定到传递给 beforeEach .解决方案是使用 .bind(this)，使用箭头函数或使用作用域为 describe 回调块的变量.

The issue is that this is not bound to the callback function passed to beforeEach. The solution is to .bind(this), use an arrow function or use a variable scoped to the describe callback block.

下面是使用箭头功能的示例:

Here's an example using an arrow function:

describe('tests', () => {
  beforeEach(async () =>
    Promise.resolve('foo').then(result => {
      this.dom = result;
    })
  );

  it('works', () => {
    console.log(this.dom); // => foo
  });
});

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