Question:
Testing an s3 upload? The method to test is
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export class ProcessData { constructor() {} async process(): Promise const data = await s3Client.send(new GetObjectCommand(bucket)); await parseCsvData(data.Body) } |
This is my attempt at the test case.
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import {S3Client} from '@aws-sdk/client-s3'; jest.mock("aws-sdk/clients/s3", () => { return { S3Client: jest.fn(() => { send: jest.fn().mockImplementation(() => { data: Buffer.from(require("fs").readFileSync(path.resolve(__dirname, "test.csv"))); }) }) } }); describe("@aws-sdk/client-s3 mock", () => { test('CSV Happy path', async () => { const processData = new ProcessData() await processData.process() } } |
The process gets to the parse method and throws an error “The bucket you are attempting to access must be addressed using the specific endpoint”
Answer:
For anyone who wants to mock the client directly, you can use the library aws-sdk-client-mock which is recommended by the AWS SDK team.
Some introductory tutorial
The initial steps:
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import fs from 'fs'; import { GetObjectCommand, S3Client } from '@aws-sdk/client-s3'; import { mockClient } from 'aws-sdk-client-mock'; const mockS3Client = mockClient(S3Client); |
And then you can mock it this way
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mockS3Client.on(GetObjectCommand).resolves({ Body: fs.createReadStream('path/to/some/file.csv'), }); |
You can also spy on the client
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const s3GetObjectStub = mockS3Client.commandcalls(GetObjectCommand) // s3GetObjectStub[0] here refers to the first call of GetObjectCommand expect(s3GetObjectStub[0].args[0].input).toEqual({ Bucket: 'foo', Key: 'path/to/file.csv' }); |