使用Jest获得错误测试读取流响应

问题描述

测试从Google Cloud Store返回readStream的函数时，出现超时错误。

// Test case
import { createResponse } from 'node-mocks-http';
it('getImage from google cloud storage',async done => {
    let res: Response = createResponse();
    let data = await controller.getImage({ image: "text data"},object,response);
});

// Function that calls google gloud storage and return object.
public async getImage(imageReqDto,baseDto,response){
    let bucket = this.storage.bucket(process.env.IMAGE_BUCKET);
    let file = bucket.file(image);
    return file.createReadStream().pipe(response);;
}

任何解决方案在接收到缓冲区数据后如何成功通过测试用例。

解决方法

这取决于您要测试的内容。如果您只是想确保返回ReadStream，请尝试使用.toBeInstanceOf()：

it('readstream is returned,when .getImage() is invoked with image data',async () => {
    const response: Response = createResponse();

    const stream = await controller.getImage({image: "text data"},object,response);

    expect(stream).toBeInstanceOf(ReadStream)
});

但是，更好的测试方法是知道预期的响应并断言ReadStream与预期值匹配。如果图像很小，则可以加载到缓冲区中进行比较。如果图像较大，则可以考虑将其存储为base64，并将实际值与预期值进行比较。