使用Mocha和Chai测试异步方法

Question

Hi guys I'm having troubles to test an async function with a fetch to a server inside. I'm using mocha with chai-as-promised. The test that is failing is: 'return proper title' I guess I would have to mock the fetch call or something, or maybe the problem is that I'm calling an async function, and as I'm executing a unit test and I don't resolve the promise. I'm not pretty sure how to achieve that. Could you help me?

The function to test is:

    import React from 'react'
import Technologies from './Technologies'
import fetch from '../../core/fetch'
let title= 'Technologies'
export default {

  path: '/technologies',

  async action () {
    const resp = await fetch('/graphql', {
      method: 'post',
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        query: '{technologies{name,icon,url}}',
      }),
      credentials: 'include',
    })
    let { data, } = await resp.json()
    if (!data || !data.technologies) throw new Error('Failed to load technologies.')
    return {
      title:title,
      component: <Technologies title={title} technologies={data.technologies} />,
    }
  },

}

And my tests:

describe('Route', () => {

  it('has right path', () => {
    expect(Route.path === '/technologies').to.be.true
  })


  it('return proper title', () => {
    const title = 'Technologies'
    expect(Route.action().title === title).to.be.true
  })
})

Answer 1

try with:

describe('Route', () => {

  it('has right path', () => {
    return expect(Route.path === '/technologies').to.be.true
  })


  it('return proper title', () => {
    const title = 'Technologies'
    return  expect(Route.action().title === title).to.be.true
  })
})

Answer 2

The first strategy suggested in the mocha documentation is using the 'done' callback. This is an extra argument to the callback in the it . You call it after the last assertion in your test.

for example, for your test you have forget to return the function in expect :

describe('Route', () => {

      it('has right path', (done) => {
        return expect(Route.path === '/technologies').to.be.true
        done();
      })


      it('return proper title', (done) => {
        const title = 'Technologies'
        return expect(Route.action().title === title).to.be.true
        done();
      })
    })