jest-dynamodb   

> Jest preset to run DynamoDB Local

Usage

$3

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

Make sure java runtime available for running DynamoDBLocal.jar

$3

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

$3

#### 2.1 Properties

##### tables

- Type: object[]
- Required: true

Array of createTable params.

- Create Table API.

##### 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'].

- dynamodb-local
- DynamoDB Local Usage Notes

##### clientConfig

- Type: object
- Required: false

Constructor params of DynamoDB client.

- Constructor Property

##### 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
`js
/**
* @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):

`js
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" ):

`js
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

`js
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

`js
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,
},
}
);
`

$3

`js
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.

$3

`
// 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

Alternatives

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

Read

- dynamodb-local
- DynamoDB Local Usage Notes
- Create Table API

Used by

- dynamodb-parallel-scan
- @nasa-gcn/dynamodb-autoincrement

See Also

- jest-mongodb

Publish

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

License

MIT © Shelf