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  • License MIT

Run your tests using Jest & DynamoDB local

Package Exports

  • @shelf/jest-dynamodb/jest-preset
  • @shelf/jest-dynamodb/jest-preset.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@shelf/jest-dynamodb) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

jest-dynamodb CircleCI npm (scoped)

Jest preset to run DynamoDB Local

Usage

0. Install

$ yarn add @shelf/jest-dynamodb --dev

Make sure java runtime available for running DynamoDBLocal.jar

1. Create jest.config.js

module.exports = {
  preset: '@shelf/jest-dynamodb',
};

2. Create jest-dynamodb-config.js

2.1 Properties

tables
  • Type: object[]
  • Required: true

Array of createTable params.

port
  • Type: number
  • Required: false

Port number. The default port number is 8000.

hostname
  • Type: string
  • Required: false

Hostname. The default hostname is localhost.

options
  • Type: string[]
  • Required: false

Additional arguments for dynamodb-local. The default value is ['-sharedDb'].

clientConfig
  • Type: object
  • Required: false

Constructor params of DynamoDB client.

installerConfig

  • Type: {installPath?: string, downloadUrl?: string}

  • Required: false

  • installPath defines the location where dynamodb-local is installed or will be installed.

  • downloadUrl defines the url of dynamodb-local package.

The default value is defined at https://github.com/rynop/dynamodb-local/blob/2e6c1cb2edde4de0dc51a71c193c510b939d4352/index.js#L16-L19

2.2 Examples

You can set up tables as an object:

Whole list of config properties can be found here

/**
 * @type {import('@shelf/jest-dynamodb/lib').Config}')}
 */
const config = {
  tables: [
    {
      TableName: `files`,
      KeySchema: [{AttributeName: 'id', KeyType: 'HASH'}],
      AttributeDefinitions: [{AttributeName: 'id', AttributeType: 'S'}],
      ProvisionedThroughput: {ReadCapacityUnits: 1, WriteCapacityUnits: 1},
    },
    // etc
  ],
  port: 8000,
};
module.exports = config;

Or as an async function (particularly useful when resolving DynamoDB setup dynamically from serverless.yml):

module.exports = async () => {
  const serverless = new (require('serverless'))();
  // If using monorepo where DynamoDB serverless.yml is in another directory
  // const serverless = new (require('serverless'))({ servicePath: '../../../core/data' });

  await serverless.init();
  const service = await serverless.variables.populateService();
  const resources = service.resources.filter(r => Object.keys(r).includes('Resources'))[0];

  const tables = Object.keys(resources)
    .map(name => resources[name])
    .filter(r => r.Type === 'AWS::DynamoDB::Table')
    .map(r => r.Properties);

  return {
    tables,
    port: 8000,
  };
};

Or read table definitions from a CloudFormation template (example handles a !Sub on TableName, i.e. TableName: !Sub "${env}-users" ):

const yaml = require('js-yaml');
const fs = require('fs');
const {CLOUDFORMATION_SCHEMA} = require('cloudformation-js-yaml-schema');

module.exports = async () => {
  const cf = yaml.load(fs.readFileSync('../cf-templates/example-stack.yaml', 'utf8'), {
    schema: CLOUDFORMATION_SCHEMA,
  });
  var tables = [];
  Object.keys(cf.Resources).forEach(item => {
    tables.push(cf.Resources[item]);
  });

  tables = tables
    .filter(r => r.Type === 'AWS::DynamoDB::Table')
    .map(r => {
      let table = r.Properties;
      if (typeof r.TableName === 'object') {
        table.TableName = table.TableName.data.replace('${env}', 'test');
      }
      delete table.TimeToLiveSpecification; //errors on dynamo-local
      return table;
    });

  return {
    tables,
    port: 8000,
  };
};

3.1 Configure DynamoDB client (from aws-sdk v2)

const {DocumentClient} = require('aws-sdk/clients/dynamodb');

const isTest = process.env.JEST_WORKER_ID;
const config = {
  convertEmptyValues: true,
  ...(isTest && {
    endpoint: 'localhost:8000',
    sslEnabled: false,
    region: 'local-env',
    credentials: {
      accessKeyId: 'fakeMyKeyId',
      secretAccessKey: 'fakeSecretAccessKey',
    },
  }),
};

const ddb = new DocumentClient(config);

3.2 Configure DynamoDB client (from aws-sdk v3)

const {DynamoDB} = require('@aws-sdk/client-dynamodb');
const {DynamoDBDocument} = require('@aws-sdk/lib-dynamodb');

const isTest = process.env.JEST_WORKER_ID;

const ddb = DynamoDBDocument.from(
  new DynamoDB({
    ...(isTest && {
      endpoint: 'http://localhost:8000',
      region: 'local-env',
      credentials: {
        accessKeyId: 'fakeMyKeyId',
        secretAccessKey: 'fakeSecretAccessKey',
      },
    }),
  }),
  {
    marshallOptions: {
      convertEmptyValues: true,
    },
  }
);

4. PROFIT! Write tests

it('should insert item into table', async () => {
  await ddb.put({TableName: 'files', Item: {id: '1', hello: 'world'}}).promise();

  const {Item} = await ddb.get({TableName: 'files', Key: {id: '1'}}).promise();

  expect(Item).toEqual({
    id: '1',
    hello: 'world',
  });
});

Monorepo Support

By default the jest-dynamodb-config.js is read from cwd directory, but this might not be suitable for monorepos with nested jest projects with nested jest.config.* files nested in subdirectories.

If your jest-dynamodb-config.js file is not located at {cwd}/jest-dynamodb-config.js or you are using nested jest projects, you can define the environment variable JEST_DYNAMODB_CONFIG with the absolute path of the respective jest-dynamodb-config.js file.

Example Using JEST_DYNAMODB_CONFIG in nested project

// src/nested/project/jest.config.js
const path = require('path');

// Define path of project level config - extension not required as file will be imported via `require(process.env.JEST_DYNAMODB_CONFIG)`
process.env.JEST_DYNAMODB_CONFIG = path.resolve(__dirname, './jest-dynamodb-config');

module.exports = {
  preset: '@shelf/jest-dynamodb'
  displayName: 'nested-project',
};

Troubleshooting

UnknownError: Not Found

Perhaps something is using your port specified in jest-dynamodb-config.js.

com.almworks.sqlite4java.Internal log WARNING: [sqlite] cannot open DB[1]:

See https://www.josephso.dev/using-jest-dynamodb-in-apple-silicon-platform-workaround/#community-build

Alternatives

  • jest-dynalite - a much lighter version which spins up an instance for each runner & doesn't depend on Java

Read

Used by

See Also

Publish

$ git checkout master
$ yarn version
$ yarn publish
$ git push origin master --tags

License

MIT © Shelf