ddb-local

ddb-local

A thin wrapper around AWS's DynamoDBLocal to make using it in unit tests a bit simpler.

Install

npm install --save ddb-local

Usage

Example usage with Mocha

Set an env var for your DynamoDB endpoint in your package.json test script

  "scripts": {
    "test": "NODE_ENV=test AWS_DDB_ENDPOINT=http://localhost:3547 mocha --timeout 30000"
  },

Start up DdbLocal before running your application tests, and shut it down after.

var DdbLocal = require('ddb-local');

describe('ddb', function () {
    var ddblocal = new DdbLocal();
    
    before(function (done) {
        ddblocal.start(done);
    }
    
    describe('application tests...');
    
    after(function (done) {
        ddblocal.stop(done);
    });
});

Then wihin your application code, any time you create a new DynamoDB client, set the endpoint if the env var is set.

    var dynamoParams = {
        apiVersion: '2012-08-10',
        endpoint: process.env.AWS_DDB_ENDPOINT
    };
    var dynamo = new AWS.DynamoDB(dynamoParams);

Now when you run $ npm test your application will be using DynamoDBLocal instead of the real DynamoDB. Keep in mind that if your application code assumes your DynamoDB tables already exist, you'll have to create them in your test setup.

Options

ddb-local supports a few configuration options via both env var and constructor params new DdbLocal(options)

• Download path for the DynamoDBLocal jar file. Set with options.jarDir or by setting DEFAULT_DOWNLOAD_PATH env var
• Port for DynamoDBLocal to listen on. Set with options.port or DDB_PORT
• Endpoint for DynamoDBLocal to use. Overrides the Port option. Set with AWS_DDB_ENDPOINT
• Whether to store data in memory (default) or files. Set options.inMemory=false or DDB_LOCAL_IN_MEMORY=false to use files.

Self-contained Example (no test framework)

var AWS = require('aws-sdk');
var DdbLocal = require('ddb-local');
var assert = require('assert');

var localdb = new DdbLocal();
localdb.start(function (err) {
    assert.ifError(err);
    // Now use DynamoDB normally, just set the endpoint to localdb.endpoint
    var AWS = require('aws-sdk');
    
    var dynamoParams = {
        apiVersion: '2012-08-10',
        endpoint: localdb.endpoint
    };
    var client = new AWS.DynamoDB(dynamoParams);
    var tableParams = {
        TableName: 'test',
		AttributeDefinitions: [
			{
				AttributeName: 'id',
				AttributeType: 'S'
			}
		],
		KeySchema: [
			{
				AttributeName: 'id',
				KeyType: 'HASH'
			}
		],
		ProvisionedThroughput: {
			ReadCapacityUnits: 5,
			WriteCapacityUnits: 5
		}
    };
    client.createTable(tableParams, function (err, result) {
        assert.ifError(err);
        assert.equal(result.TableDescription.TableName, tableParams.TableName);
        done();
    });
    
    // Stop LocalDB when you're done
    localdb.stop();
});