nodejs：测试单独通过，一起运行时失败mocha、sinon、aws-sdk

如何解决nodejs：测试单独通过，一起运行时失败mocha、sinon、aws-sdk

我有以下测试：

1. 在 VS Code 中一起运行时通过
2. 在 CLI 上一起运行时失败
3. 单独运行时通过（例如mocha bogus.test.js -g "second"）

这是我能做到的最简单的代码（而且它非常简单）：

const AWS = require("aws-sdk")
const SQS = new AWS.SQS()

exports.handler = () => {
  return SQS.deleteMessage({foo: "bar"}).promise()
}

和测试：

const sinon = require("sinon")
const expect = require("chai").expect
const AWS = require("aws-sdk")

describe("Bogus Test",() => {
  let sandBox,deleteMessageStub

  beforeEach(() => {
    sandBox = sinon.createSandBox()

    deleteMessageStub = sandBox.fake.returns({ promise: () => Promise.resolve({}) })
    sandBox.stub(AWS,'SQS').returns({
      deleteMessage: deleteMessageStub
    })  
  })

  afterEach(() => { sandBox.restore() })

  it("is the first test",() => {
    const bogus = require("../bogus")
    return bogus.handler().then(() => {
      expect(deleteMessageStub.callCount).to.equal(1,'Should have called deleteMessage once')
    })
  })

  it("is the second test",'Should have called deleteMessage once')
    })
  })
})

结果：

Bogus Test
✓ is the first test
1) is the second test


1 passing (14ms)
1 failing

1) Bogus Test
is the second test:

Should have called deleteMessage once
+ expected - actual

-0
+1

at ... bogus.test.js:29:46

我会很高兴发现我正在做一些愚蠢的事情......

解决方法

require 一个模块多次，模块作用域的代码只会执行一次，因为模块缓存在require.cache对象中。

这意味着 ./bogus 模块仅加载一次，并在第二个 require.cache 期间从 require 对象中获取。 const SQS = new AWS.SQS(); 语句将只执行一次。

您通过·sinon.restore()·清除了stub的调用信息，所以第二个测试用例的·stub.callCount·为0。

解决方案：清除./bogus钩子内beforeEach()的模块缓存

例如

bogus.js：

const AWS = require('aws-sdk');
const SQS = new AWS.SQS();

exports.handler = () => {
  return SQS.deleteMessage({ foo: 'bar' }).promise();
};

bogus.test.js：

const sinon = require('sinon');
const expect = require('chai').expect;
const AWS = require('aws-sdk');

describe('Bogus Test',() => {
  let sandbox,deleteMessageStub;

  beforeEach(() => {
    sandbox = sinon.createSandbox();

    deleteMessageStub = sandbox.fake.returns({ promise: () => Promise.resolve({}) });
    sandbox.stub(AWS,'SQS').returns({
      deleteMessage: deleteMessageStub,});
    delete require.cache[require.resolve('./bogus')];
  });

  afterEach(() => {
    sandbox.restore();
  });

  it('is the first test',() => {
    const bogus = require('./bogus');
    return bogus.handler().then(() => {
      expect(deleteMessageStub.callCount).to.equal(1,'Should have called deleteMessage once');
    });
  });

  it('is the second test','Should have called deleteMessage once');
    });
  });
});

单元测试结果：

  Bogus Test
    ✓ is the first test
    ✓ is the second test


  2 passing (9ms)