I try to mock s3 upload function with this instruction but when I use this pattern a have an
TypeError: s3.upload is not a function
// upload.test.js
const AWS = require('aws-sdk');
jest.mock('aws-sdk', () => {
const mS3 = { upload: jest.fn().mockReturnThis(), promise: jest.fn() };
return { S3: jest.fn(() => mS3) };
});
const s3 = new AWS.S3();
s3.upload({}).promise.mockResolvedValueOnce({ Bucket: 'XXX' });
I'm using also SQS and with this pattern I have another error:
AWS.SQS is not a constructor
How I can handle with it?
// upload.js
const AWS = require('aws-sdk');
const s3 = new AWS.S3();
s3Params = {
Bucket: S3_BUCKET,
Key: `example.xml`,
ACL: 'public-read',
ContentType: 'application/json',
Body: Buffer.from(file)
}
}
await s3.upload(s3Params).promise();
Instead of aws-sdk try using aws-sdk/clients/s3.
when using Jest .mockReturnValueOnce, you need to execute the mock AFTER that value is set to be able to receive the value you defined in mockReturnValueOnce as a response,
for example, mocking S3:
// s3-mock.test.js
let AWS = require('aws-sdk');
jest.mock('aws-sdk', () => {
let instance = {
upload: jest.fn().mockReturnThis(),
promise: jest.fn(),
};
return { S3: jest.fn(() => instance) };
});
describe("setup for s3.upload testing", () => {
let testS3;
beforeEach(() => {
testS3 = new AWS.S3();
testS3.promise.mockReturnValueOnce({ Bucket: 'TestBucketName' });
})
test('returns expected upload value', async () => {
let params = {};
let result = await testS3.upload(params).promise();
expect(result).toEqual({ Bucket: 'TestBucketName' });
expect(result.Bucket).toBe("TestBucketName")
});
});
and mocking SQS:
// sqs-mock.test
let AWS = require('aws-sdk');
jest.mock('aws-sdk', () => {
let instance = {
sendMessage: jest.fn().mockReturnThis(),
promise: jest.fn(),
};
return { SQS: jest.fn(() => instance) };
});
describe("setup for sqs.sendMessage testing", () => {
let testSQS;
beforeEach(() => {
testSQS = new AWS.SQS();
testSQS.promise.mockReturnValueOnce({ MessageId: 'TestSQSId' });
})
test('returns expected message id', async () => {
let params = {};
let result = await testSQS.sendMessage(params).promise();
expect(result).toEqual({ MessageId: 'TestSQSId' });
expect(result.MessageId).toBe("TestSQSId")
});
});
working example on https://github.com/oieduardorabelo/jest-mock-aws-sdk
as you can see, they are identical, you can also use manual mocks in Jest with a folder __mocks__ with all packages you and to mock in your tests, have a look at the docs on: https://jestjs.io/docs/manual-mocks