Add tests to ensure ItemNotFoundException inherits from Error

JakeChampion commented 5 years ago

Currently if an item does not exist in the dynamodb table an error is thrown but the error that is thrown is not inheriting from the error class they are constructed from. It turns out this is a bug/intential-change in TypeScript. TypeScript have a page on their Wiki which explains how to extend from Error correctly -- https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#extending-built-ins-like-error-array-and-map-may-no-longer-work

import {
    DataMapper,
    DynamoDbSchema,
    DynamoDbTable,
} from '@aws/dynamodb-data-mapper';
import DynamoDB = require('aws-sdk/clients/dynamodb');

const client = new DynamoDB({
    region: 'us-west-2'
});
const mapper = new DataMapper({
    client
});

class MyDomainModel {
    id: string;
}

Object.defineProperties(MyDomainModel.prototype, {
    [DynamoDbTable]: {
        value: 'MyTable'
    },
    [DynamoDbSchema]: {
        value: {
            id: {
                type: 'String',
                keyType: 'HASH'
            },
        },
    },
});

async function main() {
    // delete an object
    const toDelete = new MyDomainModel();
    toDelete.id = 'DELETE_ME';
    // this throws as it's fetching an object that does not exist,
    // the error should be an instance of ItemNotFoundException
    await mapper.get(toDelete)
        .catch(err => console.log(err instanceof ItemNotFoundException)); // <---- This should be true but currently is false
}

main();