MongoDB Test Hook

mongo-hook.js

const co = require('co');
const portfinder = require('portfinder');
const mongoServer = require('mongodb-prebuilt');
const tmp = require('tmp');
tmp.setGracefulCleanup();

var db, mongoDataTmp;

before(() => co(function*() {
  const dsn = process.env.MONGO_DB_DSN || (yield startMongoServer());

  db = yield cb => require('mongodb').MongoClient
    .connect(dsn, cb);

  console.log(`MongoDB is up and running at ${dsn}`);
}));

function startMongoServer() {
  return co(function* () {
    const dbPort = yield cb => portfinder.getPort(cb);
    console.log(`Starting MongoDB server on ${dbPort}...`);

    // Create a mongo data dir
    mongoDataTmp = yield cb => tmp.dir({ unsafeCleanup: true },
      (err, path, cleanup) => cb(err, { path, cleanup })
    );

    // Start the mongo server
    const mongoStatus = mongoServer.start_server({
      args: { port: dbPort, dbpath: mongoDataTmp.path },
      auto_shutdown: true
    }, errorCode => {
      // Sometimes mongoServer sends errors here
      // (but not successes)
      if (errorCode) {
        console.error(`mongo exited with ${errorCode}`)
      }
    });
    // mongodb-prebuilt has crappy error handling
    if (mongoStatus !== 0) {
      throw new Error(`Failed to start mongodb server`);
    }

    return `mongodb://localhost:${dbPort}/test_db`;
  })
}

// Reset DB after each test, so we can start with a clean slate.
afterEach((done) => db.dropDatabase(done));

// Destroy the MongoDB server
after(() => {
  try {
    // Delete the data dir
    mongoDataTmp.cleanup();
  }
  catch (err) {
    // This happens sometimes, but I don't want it to break tests.
    console.warn(`Failed to delete temp mongo data dir at ${mongoDataTmp.path}`);
  }
  mongoServer.shutdown();
});

module.exports = function getDb() {
  return db;
}

Mocha hook to spin up a MongoDB server for tests.