Exploring NestJs: A comprehensive guide to testing response controllers

Question

Exploring NestJs: A comprehensive guide to testing response controllers

I am looking to use Jest to test the responses from my API. This method is from my controller.

  @Post('send-banana')
  async sendBanana(
    @Body() request: BananaRequest,
    @Res() res: Response,
  ) {
    const responseCodeService = await this.bananaService.sendBanana(
      request,
    )

    res.status(responseCodeService).send({
      code: responseCodeService,
      message: HttpStatus[responseCodeService],
    })
  }

Here is the test I have written:

  describe('Banana Controller', () => {
    fit('should return httpcode(201)', async () => {
      const result = await Promise['']

      const request = {
        origin: 'dummy origin',
        receiver: 'dummy@dummy',
        data: {
          name: 'Elsa Pallo',
        },
      } as BananaRequest

      const response = jest.fn((resObj) => ({
        status: jest.fn((status) => ({
          res: { ...resObj, statusCode: status },
        })),
      }))

      jest
        .spyOn(bananaService, 'sendBanana')
        .mockImplementation(() => result)

      expect(
        await bananaController.sendBanana(request, response),
      ).toBe(result)
    })
  })

I encountered an error:

https://i.sstatic.net/Q64MB.png

Could anyone provide guidance on how I can mock the response?

typescript express testing nestjs

Answer 1

Answer №1

To mock the response, you should do the following:

const mockStatusResponse = {
  send: jest.fn((data) => data),
}

const mockResponse = {
  status: jest.fn((code) => mockStatusResponse),
  send: jest.fn((data) => data),
} as unknown as Response

Answer 2

To mock the response, you should do the following:

const mockStatusResponse = {
  send: jest.fn((data) => data),
}

const mockResponse = {
  status: jest.fn((code) => mockStatusResponse),
  send: jest.fn((data) => data),
} as unknown as Response

Answer 3

Answer №2

If you are utilizing foo.pipe(res), here is a custom class I created to test it:

class ResponseMock extends Writable {
    private responseText = '';

    public _write(
        chunk: string,
        encoding: BufferEncoding,
        callback: (error?: Error | null) => void
    ): void {
        this.responseText += chunk;
        callback();
    }

    /**
     * Retrieve the complete response when ready
     */
    public async getResponse(): Promise<string> {
        return await new Promise<string>((resolve): void => {
            this.on('finish', (): void => {
                resolve(this.responseText);
            });
        });
    }
}

This class can be utilized as follows:

import { Response } from 'express';

const responseMock = new ResponseMock();

await controller.query(
    param1,
    param2,
    responseMock as unknown as Response
);

await expect(responseMock.getResponse()).resolves.toEqual('foo');

Answer 4

If you are utilizing foo.pipe(res), here is a custom class I created to test it:

class ResponseMock extends Writable {
    private responseText = '';

    public _write(
        chunk: string,
        encoding: BufferEncoding,
        callback: (error?: Error | null) => void
    ): void {
        this.responseText += chunk;
        callback();
    }

    /**
     * Retrieve the complete response when ready
     */
    public async getResponse(): Promise<string> {
        return await new Promise<string>((resolve): void => {
            this.on('finish', (): void => {
                resolve(this.responseText);
            });
        });
    }
}

This class can be utilized as follows:

import { Response } from 'express';

const responseMock = new ResponseMock();

await controller.query(
    param1,
    param2,
    responseMock as unknown as Response
);

await expect(responseMock.getResponse()).resolves.toEqual('foo');

Exploring NestJs: A comprehensive guide to testing response controllers

Answer №1

Answer №2

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