出现笑话错误：“TypeError：文章不是构造函数”

Question

我试图找出为什么article.service.js 文件测试失败并出现以下错误：

TypeError: Article is not a constructor

      17 |    */
      18 |   static async saveArticle(userId, articleObj) {
    > 19 |     const newArticle = new Article();

但是，我找不到原因。

我将

Article

中的

article.model.js

声明为基于正常模式的正常 Mongoose 模型：

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const articleSchema = new Schema(
  {
    slug: { type: String },
    title: { type: String, required: true },
    description: { type: String, required: true },
    body: { type: String, required: true },
    tagList: [String],
    favoritesCount: { type: Number, default: 0 },
    comments: [{ type: mongoose.Types.ObjectId, ref: 'Comment' }],
    author: { type: mongoose.Types.ObjectId, ref: 'User' },
  },
  { timestamps: true }
);

const Article = mongoose.model('Article', articleSchema);
module.exports.Article = Article;

然后我在

article.service.js

中加载并使用它：

const { Article } = require('../models/article.model');
const { currentUser } = require('../services/user.service');
const { slugify } = require('../helpers/slugify.helper');

class ArticleService {
  static async saveArticle(userId, articleObj) {
    const newArticle = new Article();

    // ...more code here...
  }
}

我在测试中触发（

article.service.test.js

）为：

const slugifyHelper = require('../../../helpers/slugify.helper');
const currentUserService = require('../../../services/user.service');
const { Article } = require('../../../models/article.model');

const mockUser = {
  _id: "6368ad4347dkhs",
  email: "[email protected]"
};

const mockArticle = {
  title: "Sample article title",
  description: "Sample article description",
  body: "Sample article body",
  tagList: ['tag1', 'tag2']
};

// Mock the Article model
jest.mock('../../../models/article.model', () => ({
  save: jest.fn().mockResolvedValue(mockUser)
}));

const slugifySpy = jest.spyOn(slugifyHelper, "slugify").mockReturnValue('mocked-slug');
const currentUserSpy = jest.spyOn(currentUserService, "currentUser").mockResolvedValue(mockUser);

describe("Unit tests for article.service.js file", () => {
  beforeEach(() => {
    jest.clearAllMocks();
  });
  describe("saveArticle tests", () => {
    test("If user can save an article", async () => {
      //Arrange
      const { saveArticle } = require("../../../services/article.service");

      //Act
      const result = await saveArticle(mockUser._id, mockArticle);

      //Assert
      expect(Article).toHaveBeenCalledTimes(1);
      expect(slugifySpy).toHaveBeenCalledTimes(1);
      expect(slugifySpy).toHaveBeenCalledWith(mockArticle.title);
      expect(currentUserSpy).toHaveBeenCalledTimes(1);
      expect(currentUserSpy).toHaveBeenCalledWith(mockUser._id);
    });
  });
});

我想编写用于单元测试 saveArticle 函数的测试套件。在该测试套件中，我尝试测试 slugify 和 currentUser 函数至少被调用一次并带有必要的参数。

Answer 1

您没有正确模拟

article.model.js

模块。

article.model.js

：

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const articleSchema = new Schema(
  {
    slug: { type: String },
  },
  { timestamps: true },
);

const Article = mongoose.model('Article', articleSchema);
module.exports.Article = Article;

article.service.js

：

const { Article } = require('./article.model');

class ArticleService {
  static async saveArticle(userId, articleObj) {
    const newArticle = new Article();
    return newArticle.save();
    // ...more code here...
  }
}

module.exports = ArticleService;

const { Article } = require('./article.model');

const mockUser = {
  _id: '6368ad4347dkhs',
  email: '[email protected]',
};

const mockArticle = {
  title: 'Sample article title',
  description: 'Sample article description',
  body: 'Sample article body',
  tagList: ['tag1', 'tag2'],
};

// Mock the Article model
jest.mock('./article.model', () => {
  return {
    Article: jest.fn().mockImplementation(() => ({
      save: jest.fn().mockResolvedValue(mockUser),
    })),
  };
});

describe('Unit tests for article.service.js file', () => {
  beforeEach(() => {
    jest.clearAllMocks();
  });
  describe('saveArticle tests', () => {
    test('If user can save an article', async () => {
      const ArticleService = require('./article.service');
      const actual = await ArticleService.saveArticle(mockUser._id, mockArticle);

      expect(Article).toHaveBeenCalledTimes(1);
      expect(actual).toEqual(mockUser);
    });
  });
});