如何使用Await使用Mocha测试异步代码

Question

如何使用Mocha测试异步代码？我想使用多个await内部摩卡咖啡

var assert = require('assert');

async function callAsync1() {
  // async stuff
}

async function callAsync2() {
  return true;
}

describe('test', function () {
  it('should resolve', async (done) => {
      await callAsync1();
      let res = await callAsync2();
      assert.equal(res, true);
      done();
      });
});

这将产生以下错误：

  1) test
       should resolve:
     Error: Resolution method is overspecified. Specify a callback *or* return a Promise; not both.
      at Context.it (test.js:8:4)

如果删除done（），我得到：

  1) test
       should resolve:
     Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (/tmp/test/test.js)

Answer 1

async函数返回，Promises因此您可以执行以下操作：

describe('test', function () {
  it('should resolve', () => {
    return callAsync();
  });
});

Mocha supports Promises out-of-the-box, you just have to return the Promise. If it resolves then the test passes otherwise it fails.

You don't need done nor async for your it.

If you really want to use await:

And here's an example using async it callbacks.

async function getFoo() {
  return 'foo'
}

async function getBar() {
  return 'bar'
}

describe('Foos and Bars', () => {
  it('#returns foos and bars', async () => {
    var foo = await getFoo()
    assert.equal(foo, 'foo');

    var bar = await getBar()
    assert.equal(bar, 'bar');
  })
})

Do not declare done as an argument

If you use any of the methods described above you need to remove done completely from your code. Passing done as an argument to it() hints to Mocha that you intent to eventually call it.