如何使用 Sinon、aws-sdk-mock 模拟 AWS Service Comprehend？

Question

我是在 Typescript 中模拟的初学者。我想在我的单元测试中模拟AWS.Comprehend。我在 AWS Service Comprehend 中有此代码。

const comprehend = new AWS.Comprehend();

export const handler = async (): Promise<any> => {

const params = {
    JobName: "first-job",
    InputDataConfig: {
        S3Uri: "input_bucket_name",
        InputFormat: "ONE_DOC_PER_FILE"
    },
    OutputDataConfig: {
        S3Uri: "output_bucket_name"
    },
    DataAccessRoleArn: "role_arn"
};

const result = await comprehend.startDominantLanguageDetectionJob(params)
            .promise()
            .catch(error => {
                    throw error;
                }
            );

    return result.JobId;
};

我尝试为我的代码编写单元测试。

import { expect } from 'chai';
import * as AWSMock from 'aws-sdk-mock';
import * as AWS from 'aws-sdk';

describe('unitTest', () => {
    before(() => {
        AWSMock.setSDKInstance(AWS);
        AWSMock.mock('Comprehend', 'startDominantLanguageDetectionJob', (params, cb) => {
            cb(null, { jobId: 'test_job_id', JobStatus: 'SUBMITTED' });
        });
    });

    it('should pass', async () => {
        const result = await handler();

        expect(result).to.be.eql('test_job_id');
    });
});

但我的代码不起作用。在我看来，Comprehend 不是一个模拟。并且运行正常的 startDominantLanguageDetectionJob 不是模拟。 使用aws-sdk-mock 有什么错误？

Answer 1

如果我将 const comprehend = new AWS.Comprehend(); 移动到 handler():

export const handler = async (): Promise<any> => {
  const comprehend = new AWS.Comprehend();
 // something
}

我的测试有效。不移动怎么办？

Answer 2

您可以使用jest.mock(moduleName, factory, options) 模拟aws-sdk 包、Comprehend 类及其实例方法。

例如

index.ts:

import AWS from 'aws-sdk';

const comprehend = new AWS.Comprehend();

export const handler = async (): Promise<any> => {
  const params = {
    JobName: 'first-job',
    InputDataConfig: {
      S3Uri: 'input_bucket_name',
      InputFormat: 'ONE_DOC_PER_FILE',
    },
    OutputDataConfig: {
      S3Uri: 'output_bucket_name',
    },
    DataAccessRoleArn: 'role_arn',
  };

  const result = await comprehend
    .startDominantLanguageDetectionJob(params)
    .promise()
    .catch((error) => {
      throw error;
    });

  return result.JobId;
};

index.test.ts:

import MockAWS from 'aws-sdk';
import { handler } from './';

jest.mock('aws-sdk', () => {
  const mComprehend = {
    startDominantLanguageDetectionJob: jest.fn().mockReturnThis(),
    promise: jest.fn(),
  };
  return {
    Comprehend: jest.fn(() => mComprehend),
  };
});

describe('61497560', () => {
  afterEach(() => {
    jest.clearAllMocks();
  });
  it('should return job id', async () => {
    const mComprehend = new MockAWS.Comprehend();
    const mResponse = { JobId: 1 };
    (mComprehend.startDominantLanguageDetectionJob().promise as jest.Mocked<any>).mockResolvedValueOnce(mResponse);
    const actual = await handler();
    expect(actual).toBe(1);
    expect(mComprehend.startDominantLanguageDetectionJob).toBeCalledWith({
      JobName: 'first-job',
      InputDataConfig: {
        S3Uri: 'input_bucket_name',
        InputFormat: 'ONE_DOC_PER_FILE',
      },
      OutputDataConfig: {
        S3Uri: 'output_bucket_name',
      },
      DataAccessRoleArn: 'role_arn',
    });
    expect(mComprehend.startDominantLanguageDetectionJob().promise).toBeCalledTimes(1);
  });

  it('should throw error', async () => {
    const mComprehend = new MockAWS.Comprehend();
    const mError = new Error('network');
    (mComprehend.startDominantLanguageDetectionJob().promise as jest.Mocked<any>).mockRejectedValueOnce(mError);
    await expect(handler()).rejects.toThrow('network');
    expect(mComprehend.startDominantLanguageDetectionJob).toBeCalledWith({
      JobName: 'first-job',
      InputDataConfig: {
        S3Uri: 'input_bucket_name',
        InputFormat: 'ONE_DOC_PER_FILE',
      },
      OutputDataConfig: {
        S3Uri: 'output_bucket_name',
      },
      DataAccessRoleArn: 'role_arn',
    });
    expect(mComprehend.startDominantLanguageDetectionJob().promise).toBeCalledTimes(1);
  });
});

100% 覆盖率的单元测试结果：

 PASS  stackoverflow/61497560/index.test.ts (10.06s)
  61497560
    ✓ should return job id (8ms)
    ✓ should throw error (2ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |     100 |      100 |     100 |     100 |                   
 index.ts |     100 |      100 |     100 |     100 |                   
----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        11.292s