node.js - Mocha 测试用例在 Promise 获取数据之前执行

Question

测试用例(Test1, Test2)在promise获取数据之前执行。这是文件mockExecution.js

describe('AC 1: This is suite one', ()=>
{
    before((done)=>
    {
        promiseResp.then((data) => {
            console.log("i am in the promise");
            responseData = data;
            process.exit(0);
        }, (err) => {
            console.log('promiseResp.err', err);
            process.exit(1);
        })
        done();
    })
    it('Test1', (done)=>
    {
        expect(responseData.measure.abc).not.toBe(responseData.measure_list.abc);
        done();
    });

    it('Test2', (done)=>
    {

        expect(responseData.measure.abc).not.toBe(responseData.measure_list.abc);
        done();
    });

});

Before block 内的 PromiseResp 不执行。因此“responseData”变量没有数据，并且抛出测试用例失败。我猜想存在一些异步时间问题，但不知道如何解决它，也不知道我应该把这个“process.exit(0)”放在哪里。下面是实际输出:

AC 1: This is suite one
I am in the before
    1) Test1
    2) Test2


  0 passing (7ms)
  2 failing

  1) AC 1: This is suite one
       Test1:
     TypeError: Cannot read property 'measure' of undefined
      at Context.it (QA/mockExecution.js:160:29)

  2) AC 1: This is suite one
       Test2:
     TypeError: Cannot read property 'measure' of undefined
      at Context.it (QA/mockExecution.js:167:29)

[process business logic and prints some logs here, i can't paste here]
finished analyzing all records
i am in the promise
npm ERR! Test failed.  See above for more details.

我期望按以下顺序输出:

[process business logic and prints some logs here, I can't paste here]
finished analyzing all records
AC 1: This is suite one
    I am in the before
       I am in the promise
        1) Test1 passed
        2) Test2 paseed

Answer 1

您需要在您的then内调用done分配的responseData = data:

before((done) => {
  promiseResp.then((data) => {
    responseData = data;
    // Promise has resolved. Calling `done` to proceed to the `it` tests.
    done();
  })
  .catch((err) => {
    // Calling `done` with a truthy `err` argument, in case
    // the promise fails/rejects, to fail-early the test suite.
    done(err);
  })
})

否则，在 Promise 实际解析并分配您的 responseData 变量之前，before 会提前结束并继续进行下一个测试。

这是一个使用 before Hook 的工作示例:

const expect = require('chai').expect

const getFooValue = () => {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve('foo')
    }, 500)
  })
}

describe('#getFooValue()', function () {
  let responseData

  before(done => {
    getFooValue().then(data => {
      responseData = data
      done()
    })
    .catch(err => {
      done(err)
    })
  })

  it('response has a value of foo', () => {
    expect(responseData).to.equal('foo');
  })

  it('response is a String', () => {
    expect(responseData).to.be.a('String');
  })
})

你现在正在做的是:

• 您定义Promise。
• 您(过早地)调用 done，Mocha 继续执行 it 测试。
• it 测试在 responseData 仍未定义时运行。
• before 内的 Promise 最终解析并分配 responseData 变量。

...但那时已经太晚了。测试已经运行。