如何使用 sinon 在单元测试中存根 Mongoose 模型方法

Question

我有一个方法getTask()，看起来像这样：

const Task = require('./model');
const User = require('../users/model')

module.exports = async function getTask (key) {
    const task = await Task.findOne({key}).exec()
    const user = await User.findById(task.author).exec()
    task.author = user
    return task
};

基本上，我只是通过key找到我的任务，在users集合中找到作者，将它们组合在一起，然后在我的端点中我这样称呼它：

app.get('/task/:key', async (req, res, next) => {
    const task = await getTask(req.params.key)
    res.status(200).json(task)
})

这就是我尝试测试此方法的方式：

const { expect } = require('chai')
const sinon = require('sinon')
const sinonTest = require('sinon-test')

const Task = require('./model');
const User = require('../users/model')
const getTask = require('./services')

const test = sinonTest(sinon);

describe('Task CRUD operations', () => {

    it('should find task and user and return together', test(async function() {
        const mockUser = new User({ id: '5e684ebacb19f70020661f44', username: 'testuser' });
        const mockTask = new Task({ id: '5e684ececb19f70020661f45', key: 'TEST-1', author: mockUser });

        const mockTaskFindOne = {
            exec: function () {
                return mockTask
            }
        };

        const mockUserFindById = {
            exec: function () {
                return mockUser
            }
        };

        this.stub(Task, 'findOne').returns(mockTaskFindOne)
        this.stub(User, 'findById').returns(mockUserFindById)
        const task = getTask('TEST-1')

        sinon.assert.calledWith(Task.findOne, { key: 'TEST-1' })
        sinon.assert.calledWith(User.findById, '5e684ebacb19f70020661f44')
        // TODO: assert returned task is what I expect
    }));
});

所以我想断言Task.findOne() 和User.findById() 是用正确的参数调用的，最后验证返回的task 数据。

现在唯一的最后一行在我断言 User.findById 被调用的地方不起作用：

  Task CRUD operations
spec.js:54
    1) should find task and user and return together
spec.js:88
  0 passing (17ms)
base.js:319
  1 failing
base.js:332
  1) Task CRUD operations
       should find task and user and return together:
     AssertError: expected findById to be called with arguments 
      at Object.fail (node_modules/sinon/lib/sinon/assert.js:107:21)
      at failAssertion (node_modules/sinon/lib/sinon/assert.js:66:16)
      at Object.assert.<computed> [as calledWith] (node_modules/sinon/lib/sinon/assert.js:92:13)
      at Context.<anonymous> (tasks/services.test.js:36:22)
      at callSandboxedFn (node_modules/sinon-test/lib/test.js:103:25)
      at Context.sinonSandboxedTest (node_modules/sinon-test/lib/test.js:131:26)
      at processImmediate (internal/timers.js:445:21)

我知道这与 Promises 等有关，但我完全是新手。

我做错了什么？

我的Task 模特：

const mongoose = require('mongoose');

let TaskSchema = new mongoose.Schema({
    key: String,
    author: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'User'
    }
});

module.exports = mongoose.model('Task', TaskSchema);

我的User 模特：

const mongoose = require('mongoose');
const passportLocalMongoose = require('passport-local-mongoose');

let UserSchema = new mongoose.Schema({
    username: String,
    password: String
});

UserSchema.plugin(passportLocalMongoose);

module.exports = mongoose.model('User', UserSchema);

Answer 1

基于getTask() 函数，User.findById() 通过task.author 调用。这意味着sinon.assert.calledWith(User.findById, mockUser)。而已。

我创建了这个没有 sinon-test 的简单示例，以确保更改正确运行。

// @file stackoverflow.spec.js
const { expect } = require('chai');
const sinon = require('sinon');

const Task = require('./task.model');
const User = require('./user.model');
const getTask = require('./services');

describe('Task CRUD operations', function () {
  const sandbox = sinon.createSandbox();
  it('should find task and user and return together', async function () {
    const mockUser = { id: '5e684ebacb19f70020661f44', username: 'testuser' };
    const mockTask = { id: '5e684ececb19f70020661f45', key: 'TEST-1', author: mockUser };

    const mockTaskFindOne = sandbox.stub(Task, 'findOne');
    mockTaskFindOne.returns({
      exec: () => mockTask,
    });

    const mockUserFindById = sandbox.stub(User, 'findById');
    mockUserFindById.returns({
      exec: () => mockUser,
    });

    const task = await getTask('TEST-1');
    // Verify task.
    expect(task).to.deep.equal(mockTask);
    // Verify stub.
    expect(mockTaskFindOne.calledOnce).to.equal(true);
    expect(mockTaskFindOne.args[0][0]).to.deep.equal({ key: 'TEST-1' });
    // This is the same with above.
    expect(mockTaskFindOne.calledWith({ key: 'TEST-1' })).to.equal(true);
    expect(mockUserFindById.calledOnce).to.equal(true);
    expect(mockUserFindById.args[0][0]).to.deep.equal(mockUser);
    // This is the same with above.
    expect(mockUserFindById.calledWith(mockUser)).to.equal(true);

    // Restore stub.
    mockTaskFindOne.restore();
    mockUserFindById.restore();
    // Restore sandbox.
    sandbox.restore();
  });
});

当我使用 mocha 运行它时通过。

$ mocha stackoverflow.spec.js 


  Task CRUD operations
    ✓ should find task and user and return together


  1 passing (11ms)

$

希望这会有所帮助。