jest-dynalite

jest-dynalite

Enchaned unit testing, with a mock DynamoDB instance

jest-dynalite is a fork of @shelf/jest-dynamodb, and allows unit tests to execute real queries against a local DynamoDB instance.

Why should I use this?

Using this library makes writing quiries with dynamodb very easy, and your tests can really check if your data is manipulated in the way you expect it to be. This in turn makes your tests much more robust.

jest-dynalite was created in an attempt to address some of the most important missing features of @shelf/jest-dynamodb

Features

• Optionally clear tables between tests
• Isolated tables between test runners
• Custom directory for config (monorepo)
• Remove requirement for java

Installation

yarn add jest-dynalite -D

Config

In your package root, create a jest-dynalite-config.json with the tables schemas, and an optional basePort to run dynalite on:

{
  "tables": [
    {
      "TableName": "table",
      "KeySchema": [{ "AttributeName": "id", "KeyType": "HASH" }],
      "AttributeDefinitions": [{ "AttributeName": "id", "AttributeType": "S" }],
      "ProvisionedThroughput": {
        "ReadCapacityUnits": 1,
        "WriteCapacityUnits": 1
      }
    }
  ],
  "basePort": 8000
}

Update your sourcecode

const client = new DocumentClient({
  ...yourConfig,
  ...(process.env.MOCK_DYNAMODB_ENDPOINT && {
    endpoint: process.env.MOCK_DYNAMODB_ENDPOINT,
    sslEnabled: false,
    region: "local"
  })
});

process.env.MOCK_DYNAMODB_ENDPOINT is unqiue to each test runner.

Jest config

Simple usage (preset)

jest.config.js

module.exports = {
  ...
  preset: "jest-dynalite"
}

The simple preset config will use the config and clear tables between tests by default.

This the recommended usage, unless you have custom setupFilesAfterEnv or testEnvironment set.

More advanced

setup.js

import "jest-dynalite/dist/setupTables";

// Optional (but recommended)
import "jest-dynalite/dist/clearAfterEach";

jest.config.js

module.exports = {
  ...
  testEnvironment: "jest-dynalite/dist/environment",
  setupFilesAfterEnv: ["./setup.js"]
}

This setup should be used if you want to override the default config of clearAfterEach.

Most advanced

Specify the config dir

setupBeforeEnv.js

import { setup } from "jest-dynalite";

// You must give it a config directory
setup(__dirname);

setupAfterEnv.js

import { startDb, stopDb, createTables, deleteTables } from "jest-dynalite";

beforeAll(startDb);

// Create tables but don't delete them after tests
beforeAll(createTables);

// or
beforeEach(createTables);
afterEach(deleteTables);

afterAll(stopDb);

jest.config.js

module.exports = {
  ...
  setupFiles: ["./setupBeforeEnv.js"],
  setupFilesAfterEnv: ["./setupAfterEnv.js"]
}

This is by far the most complicated setup, but provides the ability to specifiy an environment other than jest-dynalite, and also allows you to specify a config directory.

License

MIT