Question

用Mocha＆amp; amp;编写项目测试时Chai我注意到我可能会让true.should.be.false失败，但当被测变量来自一个承诺并且期望失败时，Mocha会超时：Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

以下是我尝试过的事情（以及解决方案）的示例，希望它能在未来为某人提供帮助。

const chai = require('chai');
const should = chai.should();
const assert = chai.assert;

function getFoo() {
  return new Promise((resolve, reject) => {
    resolve({bar: true});
  });
}

describe('Example for StackOverflow', function() {

  it('will fail as expected', function() {
    true.should.be.false;
  });

  it('will also fail as expected', function() {
    var foo = {
      bar: true
    };

    foo.bar.should.be.false;
  });

  it('times out instead of fails', function(done) {
    getFoo().then(data => {
      data.bar.should.be.false;
      done();
    });
  });

  it('times out instead of fails even without arrow notation', function(done) {
    getFoo().then(function(data) {
      data.bar.should.be.false;
      done();
    });
  });

  it('should throws an error when the expectation fails, but the done() in catch() doesnt seem to matter', function(done) {
    getFoo().then(data => {
      data.bar.should.be.false;
      done();
    })
    .catch(error => {
      console.error(error);
      done();
    })
    .catch(error => {
      console.error(error);
      done();
    });
  });

  it('still throws an error in the catch() if I try to use assert.fail() inside the catch to force a failure', function(done) {
    getFoo().then(data => {
      data.bar.should.be.false;
      done();
    })
    .catch(error => {
      console.error(error);
      assert.fail(0, 1);
      done();
    })
    .catch(error => {
      console.error(error);
      done();
    });
  });

});

供参考，以下是这里的版本：

node：v5.12.0
chai：v4.1.0
mocha：v3.4.2

这与node.js how to get better error messages for async tests using mocha的不同之处在于，我特别谈到should检测到失败时发生的超时，并抛出一个未被捕获的错误，因为承诺不归还。他们的解决方案侧重于使用done - 我不需要它，因为它将承诺返回给Mocha，以便它可以捕获错误。

Answer 1

解决方法是在测试函数中返回承诺 - 我没有在我的times out instead of fails示例中执行此操作，后来我在编写示例时注意到了问这个问题。

const chai = require('chai');
const should = chai.should();
const assert = chai.assert;

function getFoo() {
  return new Promise((resolve, reject) => {
    resolve({bar: true});
  });
}

describe('Example for StackOverflow', function() {

  it('needs to return the promise for the test runner to fail the test on a thrown exception - no done necessary', function() {
    return getFoo().then(data => {
      data.bar.should.be.false;
    });
  });

});

当`should`期望失败时使用带有mocha和chai的promises时出现超时错误

1 个答案: