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  • License MIT

Run your tests using Jest & DynamoDB local

Package Exports

  • @shelf/jest-dynamodb/jest-preset

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 aws-sdk is installed as a peer dependency. And 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.

options
  • Type: string[]
  • Required: false

Addtional 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:

module.exports = {
  tables: [
    {
      TableName: `files`,
      KeySchema: [{AttributeName: 'id', KeyType: 'HASH'}],
      AttributeDefinitions: [{AttributeName: 'id', AttributeType: 'S'}],
      ProvisionedThroughput: {ReadCapacityUnits: 1, WriteCapacityUnits: 1}
    }
    // etc
  ],
  port: 8000
};

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.safeLoad(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'})
};

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: 'localhost:8000',
      sslEnabled: false,
      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'
  });
});

Troubleshooting

UnknownError: Not Found

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

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