How To Mock S3 With Jest?

I am tryng to code a test for upload. But i am not understating how to properly use jest.mock('aws-sdk') export class S3Service { private readonly s3: S3; private readonly buck

Solution 1:

Here is the unit test solution:

s3Service.ts:

import { S3 } from'aws-sdk';

exportclassS3Service {
  private readonly s3: S3;
  private readonly bucket: string;
  constructor(private readonly configService) {
    this.s3 = newS3({
      accessKeyId: this.configService.get(''),
      secretAccessKey: this.configService.get(''),
      region: this.configService.get(''),
    });
    this.bucket = this.configService.get('');
  }
  public asyncupload(name: string, contentType: string, buffer: Buffer): Promise<any> {
    const bucket = this.bucket;
    const params = { Bucket: bucket, Key: 'key', Body: buffer };
    const upload = awaitthis.s3.upload(params).promise();
    return upload;
  }
}

s3Service.test.ts:

import { S3Service } from'./s3Service';

const mS3Instance = {
  upload: jest.fn().mockReturnThis(),
  promise: jest.fn(),
};

jest.mock('aws-sdk', () => {
  return { S3: jest.fn(() => mS3Instance) };
});

describe('61830632', () => {
  it('should upload correctly', async () => {
    const configService = {
      get: jest
        .fn()
        .mockReturnValueOnce('accessKeyId')
        .mockReturnValueOnce('secretAccessKey')
        .mockReturnValueOnce('us-east')
        .mockReturnValueOnce('bucket-dev'),
    };
    mS3Instance.promise.mockResolvedValueOnce('fake response');
    const s3Service = newS3Service(configService);
    const actual = await s3Service.upload('name', 'contentType', Buffer.from('ok'));
    expect(actual).toEqual('fake response');
    expect(mS3Instance.upload).toBeCalledWith({ Bucket: 'bucket-dev', Key: 'key', Body: Buffer.from('ok') });
  });
});

unit test results with 100% coverage:

 PASS  stackoverflow/61830632/s3Service.test.ts (11.362s)
  61830632
    ✓ should upload correctly (6ms)

--------------|---------|----------|---------|---------|-------------------
File          | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
--------------|---------|----------|---------|---------|-------------------
All files     |     100 |      100 |     100 |     100 |                   
 s3Service.ts |     100 |      100 |     100 |     100 |                   
--------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        12.738s

Solution 2:

Here is my solution:

jest.mock('aws-sdk', () => {
    classmockS3 {
        getSignedUrl(op, obj) {
            return'url';
        }
    }
    return {
        ...jest.requireActual('aws-sdk'),
        S3: mockS3,
    };
});

Solution 3:

If you are using NestJS, it can be easier than you think.

File Upload Module:

import { Module } from'@nestjs/common';
import { ConfigService } from'@nestjs/config';
import { TypeOrmModule } from'@nestjs/typeorm';
import { S3 } from'aws-sdk';
import { FileUploadController } from'./file-upload.controller';
import { FileUploadRepository } from'./file-upload.repository';
import { FileUploadService } from'./file-upload.service';
@Module({
  imports: [TypeOrmModule.forFeature([FileUploadRepository])],
  controllers: [FileUploadController],
  providers: [
    FileUploadService,
    {
      provide: S3,
      useFactory: (configService: ConfigService) =>
        new S3({
          accessKeyId: configService.get('AWS_ACCESS_KEY'),
          secretAccessKey: configService.get('AWS_ACCESS_SECRET'),
          region: configService.get('AWS_REGION'),
        }),
    },
  ],
})
export classFileUploadModule {}

The service itself:

import { Injectable, InternalServerErrorException } from'@nestjs/common';
import { ConfigService } from'@nestjs/config';
import { InjectRepository } from'@nestjs/typeorm';
import { S3 } from'aws-sdk';
import { v4 as uuid } from'uuid';
import { FileUpload } from'./file-upload.entity';
import { FileUploadRepository } from'./file-upload.repository';

@Injectable()
exportclassFileUploadService {
  constructor(@InjectRepository(FileUploadRepository)
    privatereadonly publicFileRepository: FileUploadRepository,
    privatereadonly configService: ConfigService,
    privatereadonly s3: S3,
  ) {}

  asyncuploadPublicFile(
    dataBuffer: Buffer,
    filename: string,
  ): Promise<FileUpload> {
    const uploadResult = awaitthis.s3
      .upload({
        Bucket: this.configService.get('AWS_BUCKET_NAME'),
        Body: dataBuffer,
        Key: `${uuid()}-${filename}`,
      })
      .promise();

    const createdFile = this.publicFileRepository.create({
      key: uploadResult.Key,
      url: uploadResult.Location,
    });
    awaitthis.publicFileRepository.save(createdFile);
    return createdFile;
  }

  asyncdeletePublicFile(
    publicFileId: string,
    publicFileKey: string,
  ): Promise<FileUpload> {
    const response = awaitthis.s3
      .deleteObject({
        Bucket: this.configService.get('AWS_BUCKET_NAME'),
        Key: publicFileKey,
      })
      .promise();
    if (!response) {
      thrownewInternalServerErrorException(
        `Could not delete file ${publicFileKey}`,
      );
    }
    const { raw: deletedItem } = awaitthis.publicFileRepository.delete(
      publicFileId,
    );
    return deletedItem;
  }
}

and then finally the test:

import { InternalServerErrorException } from'@nestjs/common';
import { ConfigService } from'@nestjs/config';
import { Test, TestingModule } from'@nestjs/testing';
import { S3 } from'aws-sdk';
import { mockFileUpload } from'./file-upload.mock';
import { FileUploadRepository } from'./file-upload.repository';
import { FileUploadService } from'./file-upload.service';

exportconstmockFileUploadRepository = () => ({
  create: jest.fn(),
  save: jest.fn(),
  delete: jest.fn(),
});

const mS3Instance = {
  upload: jest.fn().mockReturnThis(),
  promise: jest.fn(),
  deleteObject: jest.fn().mockReturnThis(),
};

describe('FileUploadService', () => {
  letservice: FileUploadService;
  let repository;
  let s3Service;

  beforeEach(async () => {
    constmodule: TestingModule = awaitTest.createTestingModule({
      providers: [
        FileUploadService,
        {
          provide: FileUploadRepository,
          useFactory: mockFileUploadRepository,
        },
        {
          provide: ConfigService,
          useValue: {
            get: jest.fn(),
          },
        },
        {
          provide: S3,
          useFactory: () => mS3Instance,
        },
      ],
    }).compile();

    service = module.get<FileUploadService>(FileUploadService);
    repository = module.get<FileUploadRepository>(FileUploadRepository);
    repository = module.get<FileUploadRepository>(FileUploadRepository);
    s3Service = module.get<S3>(S3);
  });

  describe('FileUploadService.uploadPublicFile', () => {
    it('should create public file and throw no error', async () => {
      repository.create.mockResolvedValue(mockFileUpload);
      repository.save.mockResolvedValue(mockFileUpload);

      s3Service.promise = jest.fn().mockResolvedValue({
        Key: 'some-key',
        Location: 'some-location',
      });

      const file = Buffer.alloc(513, '0');
      const response = await service.uploadPublicFile(file, 'somefilename');
      expect(response).toBeDefined();
    });
  });

  describe('FileUploadService.deletePublicFile', () => {
    it('should delete public file and throw no error', async () => {
      repository.delete.mockResolvedValue({ raw: mockFileUpload });
      repository.save.mockResolvedValue(mockFileUpload);

      s3Service.promise = jest.fn().mockResolvedValue({
        Key: 'some-key',
        Location: 'some-location',
      });

      const response = await service.deletePublicFile('someid', 'somefilename');
      expect(response).toBeDefined();
    });

    it('should not delete public file and throw InternalServerErrorException', async () => {
      repository.delete.mockResolvedValue({ raw: mockFileUpload });
      repository.save.mockResolvedValue(mockFileUpload);

      s3Service.promise = jest.fn().mockResolvedValue(null);

      const promise = service.deletePublicFile('someid', 'somefilename');
      expect(promise).rejects.toThrow(InternalServerErrorException);
    });
  });
});