mocha async/await 测试因超时而失败

Question

我想用 Mocha 测试异步代码。

我遵循了本教程 testing-promises-with-mocha。最后，它说最好的方法是async/await。

以下是我的代码，我打算将 setTimeout 设置得比 Mocha 默认值长。

describe('features', () => {
  it('assertion success', async() => {
    const resolvingPromise = new Promise( resolve => {
      setTimeout(() => {
        resolve('promise resolved')
      }, 3000)
    })

    const result = await resolvingPromise
    expect(result).to.equal('promise resolved')
  })
})

Mocha 给我的错误如下：

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

如何解决错误？简单设置mocha --timeout 10000更长？

感谢您的宝贵时间！

Mocha: 5.2.0
Chai: 4.2.0

Answer 1

对于异步测试，您应该调用 done() 回调。

describe('features', () => {
  it('assertion success', async(done) => { // pass done here
    const resolvingPromise = new Promise( resolve => {
      setTimeout(() => {
        resolve('promise resolved')
      }, 3000)
    })

    const result = await resolvingPromise
    expect(result).to.equal('promise resolved')
    done() // invoke at end
  })
})

Answer 2

Mocha 有超时控制。 Mocha docs

语法是：

it('should take less than 500ms', function(done) {
  this.timeout(5000); // 5 seconds
  setTimeout(done, 3000);
});

你的例子：

describe('features', () => {
  it('assertion success', async (done) => {
    this.timeout(5000);
    const resolvingPromise = new Promise(resolve => {
      setTimeout(() => resolve('promise resolved'), 3000)
    });

    const result = await resolvingPromise();
    expect(result).to.equal('promise resolved');
    done();
  });
});

Answer 3

正如您提到的，--timeout 标志可以完成这项工作。

node ./node_modules/mocha/bin/mocha --timeout <milliseconds>

如果要在整个项目中设置默认超时，您还可以检查：Change default timeout for mocha。

mocha async/await 测试因超时而失败

mocha async/await test failed with timeout

mocha.js

async-await