jest-dynamodb 
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 -
installPathdefines the location where dynamodb-local is installed or will be installed. -
downloadUrldefines 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: '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',
});
});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 --tagsLicense
MIT © Shelf