Question

你好，我开始用 jest 研究单元测试，我有一个类有一个返回值的函数我想测试该函数的返回值，但我不知道这样做的正确方法是什么

>

类：

interface HelloWord {
    hello: string
}

export class HelloWordController extends Controller{
    async handle (request: HelloWord): Promise<HttpResponse> {
        return ok({message: 'hello word'})
    }
}

确定：返回：

export const ok = (data: any): HttpResponse => ({
  statusCode: 200,
  body: data
})

测试：

describe("Hello word Controller ", () => {
  it("should receive a string with name: hello, and value: hello word", () => {
        const logger = new adptLogger({})
        const hellowordController = new HelloWordController(logger)
        expect(hellowordController.handle({hello: 'hello word'})).toEqual(ok)
    });
});

我失败了：

Expected: [Function ok]
Received: {}

   7 |              const logger = new adptLogger({})
   8 |              const hellowordController = new HelloWordController(logger)
>  9 |              expect(hellowordController.handle({hello: 'hello word'})).toEqual(ok)
     |                                                                        ^
  10 |      });
  11 | });

已编辑：

describe("Hello word Controller ", () => {
  let controller = {} as HelloWordController;
  let logger: adptLogger = {} as adptLogger;
  beforeEach(() => {
    logger = new adptLogger({});
    controller = new HelloWordController(logger);
  });
  afterEach(() => {
    jest.restoreAllMocks();
  });

  it("should receive a string with name: hello, and value: hello word", async () => {
    const expedtedReturn = {
      statusCode: 200,
      body: { message: "hello word" },
    };
    expect(await controller.handle({ hello: "hello word" })).toEqual(
      expedtedReturn
    );
  });

  it("should receive a bad string, and receive a bad request", async () => {
    const expedtedError = {
      statusCode: 400,
      body: new Error(`bad Request`),
    };
    expect(await controller.handle({ hello: "aaa" })).toEqual(expedtedError);
  });
});

Answer 1

你需要监视你的方法。

如果你要添加更多的测试，用beforeEach来监听应该没问题，然后用afterEach恢复它们，这样你就可以控制返回值了。

你的方法是异步的，所以你的测试也应该，比如：

describe("Hello word Controller ", () => {
  const mockedResponse = { message: "hello word" };

  beforeEach(() => {
    const controllerSpy = jest.spyOn(HelloWordController, "handle");
    controllerSpy.mockReturnValue(Promise.resolve(mockedResponse));
  });

  afterEach(() => {
    jest.restoreAllMocks();
  });

  it("should receive a string with name: hello, and value: hello word", async () => {
        const logger = new adptLogger({})
        const hellowordController = new HelloWordController(logger)
        expect(await hellowordController.handle()).toEqual(mockedResponse);
    });
});

用玩笑检查函数返回

1 个答案: