笑话：如何避免 beforeEach / afterEach 中的样板

Question

我有多个服务测试几乎相等beforeEach()和afterAll() 。 可以做些什么来消除样板文件？

它看起来像这样简化：

describe('Test',()=>{
  let serverTestbed:ServerTestbed;
  let myService:MyService;
  beforeEach(()=>{
    serverTestbed= new ServerTestbed()
    serverTestbed.run()

    myService= new MyService(serverTestbed.host,serverTestbed.port) 
    //^^ this is the only line that differs from test to test
  })

  afterEach(async ()=>{
    await serverTestbed.close()

  })
})

是否可以做这样的事情，其中describeServerTest(..)包含重复的操作：

describeServerTest("test my service",(serverTestbed)=>{
  let myService:MyService
  //more varibales here

  beforeEach(()=>{
   myService= new MyService(serverTestbed.host,serverTestbed.port) 
   //other init stuff
  })

  it('test',()=>{
    myService.foo()
    expect(..)
  })
})

Answer 1

我假设您想在每个测试文件中导入describeServerTest function 而不是使用setupFilesAfterEnv配置的全局设置。

从文档定义测试中，我们知道：

必须同步定义测试，Jest 才能收集您的测试。

例如

test-utils.ts ：

const serverTestbed = {
  host: '127.0.0.1',
  port: 5432,
};
type EmptyFunction = () => void;
interface FunctionLike {
  readonly name: string;
}
export const describeServerTest = (name: number | string | Function | FunctionLike, fn: EmptyFunction): void => {
  describe(name, () => {
    beforeEach(() => {
      console.log('server testbed run');
    });

    afterEach(async () => {
      console.log('server testbed close');
    });

    fn();
  });
};

a.test.ts ：

import { describeServerTest } from './test-utils';

describeServerTest('test a service', () => {
  it('should pass', () => {
    console.log('a service test case run');
    expect(1 + 1).toEqual(2);
  });
});

b.test.ts ：

import { describeServerTest } from './test-utils';

describeServerTest('test b service', () => {
  it('should pass', () => {
    console.log('b service test case run');
    expect(1 + 1).toEqual(2);
  });
});

测试结果：

 PASS  stackoverflow/75135319/b.test.ts (8.032 s)
  ● Console

    console.log
      server testbed run

      at Object.<anonymous> (stackoverflow/75135319/test-utils.ts:12:15)

    console.log
      b service test case run

      at Object.<anonymous> (stackoverflow/75135319/b.test.ts:5:13)

    console.log
      server testbed close

      at stackoverflow/75135319/test-utils.ts:16:15

 PASS  stackoverflow/75135319/a.test.ts (8.048 s)
  ● Console

    console.log
      server testbed run

      at Object.<anonymous> (stackoverflow/75135319/test-utils.ts:12:15)

    console.log
      a service test case run

      at Object.<anonymous> (stackoverflow/75135319/a.test.ts:5:13)

    console.log
      server testbed close

      at stackoverflow/75135319/test-utils.ts:16:15


Test Suites: 2 passed, 2 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        8.997 s, estimated 10 s
Ran all test suites related to changed files.