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

Question

我有以下测试：

1. 在VS代码中一起运行时通过
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"(

这是我能做的最简单的代码(而且非常简单(：

const AWS = require("aws-sdk")
const SQS = new AWS.SQS()
exports.handler = () => {
return SQS.deleteMessage({foo: "bar"}).promise()
}

以及测试：

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", () => {
const bogus = require("../bogus")
return bogus.handler().then(() => {
expect(deleteMessageStub.callCount).to.equal(1, '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

如果我发现自己在做一些愚蠢的事情，我会很高兴。。。

Answer 1

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

这意味着./bogus模块只加载一次，并且是在第二个require期间从require.cache对象获得的。const SQS = new AWS.SQS();语句将只执行一次。

您通过sinon.restore()清除了存根的调用信息，因此第二个测试用例的stub.callCount是0。

解决方案：清除beforeEach()钩子内./bogus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', () => {
const bogus = require('./bogus');
return bogus.handler().then(() => {
expect(deleteMessageStub.callCount).to.equal(1, 'Should have called deleteMessage once');
});
});
});

单元测试结果：

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

2 passing (9ms)