Question

我一直很难找到有关如何使用jest.fn()来模拟类上的打字稿类和方法的良好资源（例如表达'Request，Response和{{ 1}}和猫鼬模型上的NextFunction方法。）

举个例子，假设我有以下模型和控制器：

模型/ Foo.ts：

save()

控制器/ foo.ts：

import * as mongoose from "mongoose"

export type FooModel = mongoose.Document & {
  owner: mongoose.Schema.Types.ObjectId,
  bars: string[]
}

const fooSchema = new mongoose.Schema({
  owner: { type: mongoose.Schema.Types.ObjectId, ref: "User", index: true },
  bars: [String]
}

export const Foo = mongoose.model<FooModel>("Foo", fooSchema)

我想添加一些单元测试：

import { Request, Response, NextFunction } from "express";
import { Foo, FooModel } from "../models/Foo";

export let createFoo = async (req: Request, res: Response, next: NextFunction) => {
  try {
    const foo = new Foo({
      owner: req.user._id,
      bars: req.body.bars
    });
    await foo.save();
    res.status(200).json(foo);
  } catch (err) {
    next(err)
  }
}

我遇到的主要问题是注释掉的部分：我还没弄清楚如何实际模拟import { Request, Response, NextFunction } from "express"; import { Foo } from "../../src/models/Foo"; import * as fooController from "../../src/controllers/foo"; import {} from "jest"; describe("createFoo", async () => { let req: Request; let res: Response; let next: NextFunction; const bars = ["baz", "qux", "quux"]; beforeEach(() => { // Mock req, res and next // Set req.body.bars equal to bars // Stub out Foo.save() so that we don't actually save to the db }); it("should add bars to the foo", async () => { await fooController.createFoo(req, res, next); responseData = JSON.parse(res.json) expect(responseData.bars).toEqual(bars); }); it("should save the foo", async () => { await fooController.createFoo(req, res, next); expect(Foo.prototype.save).toHaveBeenCalled(); } it("should call next on error", async () => { const err = new Error(); // Set up Foo.save() to throw err await fooController.createFoo(req, res, next); expect(next).toHaveBeenCalledWith(err); } });，req和res，或者如何存根退出next或使其抛出错误。我怎么能做到这一点？

Answer 1

要模拟请求和响应对象，只需将它们与所使用的值一起传递即可。您的情况如下：

import { Request, Response, NextFunction } from 'express';
import { Foo } from '../../src/models/Foo';
import * as fooController from '../../src/controllers/foo';
import { doesNotReject } from 'assert';

describe('createFoo', async () => {
  it('should add bars to the foo', async () => {
    /**
     * Spy on the model save function and return a completed promise.
     * We are not testing the model here, only the controller so this is ok.
     */
    jest.spyOn(Foo.prototype, 'save').mockImplementationOnce(() => Promise.resolve());

    /**
     * Create a mock request and set type to any to tell typescript to ignore type checking
     */
    const mockRequest: any = {
      user: {
        _id: 1234,
      },
      body: {
        bars: ['baz', 'qux', 'quux'],
      },
    };

    /**
     * Create a mock repsonse with only the methods that are called in the controller and
     * record their output with jest.fn()
     */
    const mockResponse: any = {
      status: jest.fn(),
      json: jest.fn(),
    };

    /**
     * Create a mock next function. It is okay to set its type to Express's NextFunction because
     * we are mocking the entire function.
     */
    const mockNext: NextFunction = jest.fn();

    await fooController.createFoo(mockRequest, mockResponse, mockNext);

    expect(mockResponse.json).toHaveBeenCalledTimes(1);
    expect(mockResponse.json).toHaveBeenCalledWith('bars');

    expect(mockResponse.status).toHaveBeenCalledTimes(1);
    expect(mockResponse.status).toHaveBeenCalledWith(200);
  });
});

我希望这会有所帮助！

在打字稿中嘲笑表达和猫鼬

1 个答案: