Building Applications with TypeScript - Snippet 20

bawts-20.js

/*
 * Import the libaries that we're using.
 * This is a test of API code, so any libraries
 * specified in package.json should be available
 * for import here.
 */
import chai = require('chai');
import chaiAsPromised = require("chai-as-promised");
import sinon = require('sinon');

// Bring in the Mongo client since we're going to stub it out.
import Mongo = require('mongodb');

// Bring in the class we want to test.
import {EnvDataConfig, MongoDataDriver} from '../api/db';

// Augment our pre-orders and our test expectations.
chai.use(chaiAsPromised);
var expect = chai.expect;

describe('MongoDataDriver', () => {
    var driver,
        connectStub;

    beforeEach(() => {
        driver = new MongoDataDriver(EnvDataConfig.getInstance());
        connectStub = sinon.stub(Mongo.MongoClient, 'connect');
    });

    afterEach(() => {
        /*
         * When you stub a method using Sinon, it attaches
         * a 'restore' method that you'll need to call after
         * your test finishes as part of cleanup. Of course,
         * that's not part of the type associated with MongoClient,
         * so the TypeScript compiler will complain about this
         * unless we access the restore method using an object key.
         */
        Mongo.MongoClient.connect['restore']();
    });

    describe('getConnection', () => {
        it('should reject the promise if an error occurs on connect', () => {
            connectStub.callsArgWith(1, {});

            expect(driver.getConnection()).to.eventually.be.rejected;
        });

        it('should resolve the promise if no error occurred on connect', () => {
            connectStub.callsArgWith(1, undefined);

            expect(driver.getConnection()).to.eventually.be.fulfilled;
        });

        it('should resolve the promise with the connection from the Mongo driver', () => {
            var expected = {};

            connectStub.callsArgWith(1, undefined, expected);

            expect(driver.getConnection()).to.eventually.equal(expected);
        });
    });
});