如何使用Node-fetch，supertest和打字稿设置莫克

Question

我正在尝试为我的Node typescipt项目添加一些开玩笑的测试。我想使用supertest调用我的koa路由器，但也使用fetch mock来模拟使用node-fetch提出的请求。

到目前为止，我的解决方案在下面，但是我的路由器中的获取并不使用带有Fetch Mock的模拟提取设置。单位测试失败，因为我嘲笑的预期响应未返回。我已经尝试按照文档进行嘲弄，但没有成功，打字稿使得很难遵循我发现的非typecript解决方案。如果可能的话，我想避免使用非全球沙箱，因为我必须重新编写大量代码才能传递。

server.spec.ts

import * as fetchMock from 'fetch-mock';
import * as request from 'supertest';
import server from './server';
afterEach(() => {
  server.close();
  fetchMock.reset();
});
describe('router', () => {
  test('GET: should return data', async () => {
    const expectedResponse = { test: 'TEST' };
    fetchMock.get('https://myapi.com/test', expectedResponse);
    const response = await request(server).get('/test');
    expect(response.status).toEqual(200);
    expect(response.body).toMatchObject(expectedResponse);
  });
});

server.ts

import * as Koa from 'koa';
import * as Router from 'koa-router';
import fetch from 'node-fetch';
const app = new Koa();
const router = new Router();
router.get('/test', async ctx => {
  const options = { method: 'GET' };
  try {
    const response = await fetch('https://myapi.com/test', options);
    ctx.body = await response.json();
  } catch (error) {
    error.fetchUrl = url;
    throw error;
  }
});
app.use(router.routes());
const server = app.listen(3000);
export default server;

Answer 1

您可以自己手动嘲笑node-fetch模块。这是解决方案：

server.ts：

import Koa from 'koa';
import Router from 'koa-router';
import fetch from 'node-fetch';
const app = new Koa();
const router = new Router();
router.get('/test', async ctx => {
  const options = { method: 'GET' };
  const url = 'https://myapi.com/test';
  try {
    const response = await fetch(url, options);
    ctx.body = await response.json();
  } catch (error) {
    error.fetchUrl = url;
    throw error;
  }
});
app.use(router.routes());
function createHttpServer() {
  return app.listen(3000);
}
if (require.main === module) {
  createHttpServer();
}
export default createHttpServer;

server.spec.ts：

import request from 'supertest';
import createHttpServer from './server';
import fetch from 'node-fetch';
const { Response } = jest.requireActual('node-fetch');
const server = createHttpServer();
jest.mock('node-fetch', () => jest.fn());
afterAll(done => {
  server.close(done);
});
describe('router', () => {
  test('GET: should return data', async () => {
    const expectedResponse = { test: 'TEST' };
    (fetch as jest.MockedFunction<typeof fetch>).mockResolvedValueOnce(new Response(JSON.stringify(expectedResponse)));
    const response = await request(server).get('/test');
    expect(response.status).toEqual(200);
    expect(response.body).toEqual(expectedResponse);
  });
  test('GET: should throw error', async () => {
    const mockedFetchError = new Error('some error');
    (fetch as jest.MockedFunction<typeof fetch>).mockRejectedValueOnce(mockedFetchError);
    const response = await request(server).get('/test');
    expect(response.status).toEqual(500);
  });
});

带有覆盖范围报告的单位测试结果：

 PASS  src/stackoverflow/56735795/server.spec.ts (8.487s)
  router
    ✓ GET: should return data (51ms)
    ✓ GET: should throw error (15ms)
  console.error node_modules/koa/lib/application.js:200
    undefined
  console.error node_modules/koa/lib/application.js:201
      Error: some error
          at Object.<anonymous> (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/56735795/server.spec.ts:26:30)
          at step (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/56735795/server.spec.ts:32:23)
          at Object.next (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/56735795/server.spec.ts:13:53)
          at /Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/56735795/server.spec.ts:7:71
          at new Promise (<anonymous>)
          at Object.<anonymous>.__awaiter (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/56735795/server.spec.ts:3:12)
          at Object.<anonymous> (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/src/stackoverflow/56735795/server.spec.ts:25:35)
          at Object.asyncJestTest (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/jasmineAsyncInstall.js:102:37)
          at resolve (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/queueRunner.js:43:12)
          at new Promise (<anonymous>)
          at mapper (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/queueRunner.js:26:19)
          at promise.then (/Users/ldu020/workspace/github.com/mrdulin/jest-codelab/node_modules/jest-jasmine2/build/queueRunner.js:73:41)
          at process._tickCallback (internal/process/next_tick.js:68:7)
  console.error node_modules/koa/lib/application.js:202
    undefined
-----------|----------|----------|----------|----------|-------------------|
File       |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-----------|----------|----------|----------|----------|-------------------|
All files  |    95.24 |       50 |      100 |    94.12 |                   |
 server.ts |    95.24 |       50 |      100 |    94.12 |                28 |
-----------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        10.36s

这是完整的演示：https：//github.com/mrdulin/jest-codelab/tree/master/master/src/stackoverflow/56735795

Answer 2

我试图使用手动全局模拟与jest和打字稿一起使用node-fetch模拟，以及其他答案中建议的一堆不同的软件包。这是对我有用的唯一一件事；

安装'开玩笑莫克'

创建测试;

// To mock fetch we need to import and enable before all other imports
import { enableFetchMocks } from 'jest-fetch-mock';
enableFetchMocks();
import ...
import ...
import ...
import fetch from 'node-fetch';
describe("I lost too many hours on this", () => {
    let spyFetch;
    beforeAll(() => {
        spyFetch = (fetch as jest.MockedFunction<typeof fetch>);
        spyFetch.mockImplementation(() => Promise.resolve({json: () => 'YMMV'}));
    });
    afterEach(() => {
        spyFetch.mockClear();
    });
    it("Call method which contains fetch", async () => {
        // Setup
        ...
        await exampleClass.methodContainingFetch('TestUrl');
        expect(spyFetch.mock.calls[0][0]).toBe('TestUrl');
    });
});

如果您有打字稿类型的构图问题，我使用了

spyFetch = (fetch as any)

上面缺少超级巨星，但我怀疑人们遇到这个问题的问题是否有问题。