CODEWITHSUNDEEP
node.jsamazon-web-servicesamazon-dynamodbaws-sdk
Jayanth Mogadampalli
Jayanth Mogadampalli

Reputation: 71

How to mock an Amazon DynamoDB v3 in Nodejs using Jest?

I am using an Amazon DynamoDB package from aws-sdk v3 for javascript.
Here is the docs which I have followed: https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-examples.html
I have installed "@aws-sdk/client-dynamodb" package to perform CRUD operations from code.
I have imported commands from package in this way:

import { DynamoDBClient, PutItemCommand, DeleteItemCommand, UpdateItemCommand, GetItemCommand } from "@aws-sdk/client-dynamodb";
const dynamodbClient = new DynamoDBClient({ region: process.env.DYNAMODB_REGION, endpoint: process.env.DYNAMODB_ENDPOINT });
const result = await dynamodbClient.send(new PutItemCommand(params));

I have tried to mock Amazon DynamoDB following Jest docs but it was calling real Amazon DynamoDB in local.

How to mock these "@aws-sdk/client-dynamodb" package in Nodejs?
Please provide an example in Nodejs!

Upvotes: 3

Views: 6622

Answers (4)

Interlated
Interlated

Reputation: 5926

AWS recommends mocking DynamoDB and the rest of AWS with aws-sdk-client-mock with documentation included with the module.

Install aws-sdk-client-mock and probably aws-sdk-client-mock-jest

npm i aws-sdk-client-mock aws-sdk-client-mock-jest

Import the module

import {mockClient} from "aws-sdk-client-mock";
import 'aws-sdk-client-mock-jest';

Create a mock. Reset after each test

describe('Winner purge service', () => {
  const ddbMock = mockClient(DynamoDBClient)

  beforeEach(() => {
    jest.clearAllMocks()
    ddbMock.reset()
  })

Define responses

    ddbMock
        .on(ScanCommand).resolvesOnce({
        Items: [marshall(configItem, {removeUndefinedValues: true})],
        Count: 1
    })
    ddbMock.on(QueryCommand)
        .resolvesOnce({
            Items: [marshall(olderWinner)], Count: 1
        })
        .resolves({
            Items: [], Count: 0
        })

Test calls

expect(ddbMock.commandCalls(DeleteItemCommand).length).toBe(0)

Upvotes: 2

vamsiampolu
vamsiampolu

Reputation: 6622

You should install the aws dynamodb jar and use an endpoint with your dynamodb client.

You can setup a docker container to run dynamodb:

$ docker run -d -p 8000:8000 instructure/dynamo-local-admin:latest

When you setup the dynamodb client for your tests, keep using the endpoint:

import { DynamoDBClient, PutItemCommand, DeleteItemCommand, UpdateItemCommand, GetItemCommand } from "@aws-sdk/client-dynamodb";
const dynamodbClient = new DynamoDBClient({ region: process.env.DYNAMODB_REGION, endpoint: process.env.DYNAMODB_ENDPOINT });
const result = await dynamodbClient.send(new PutItemCommand(params));

After you run your tests, you can check the results on the admin UI available at localhost:8000.

Upvotes: 0

r_dmr
r_dmr

Reputation: 193

You can use AWSMock along with sinon and mock the method and response as you want. It works really great with jest and it doesn't call a real database.

Upvotes: 1

Alberto S.
Alberto S.

Reputation: 2105

This answer may come a bit late :) Currently there are two very useful package to deal with aws dynamodb mocks

I my case, I ended up using the second option, jest-dynalite since it doesnt require java and its very easy to configure :)

Upvotes: 1

Related Questions