Automated Testing with Databases - node.js

Question

I'm fairly new to automated testing and was wondering how I should go about writing tests for the database. The project I'm working on right now is running PostgreSQL with Sequelize as the ORM on a Node.JS environment. If it matters, I'm also using Jest as the testing library right now.

Answer 1

In my app I use a config module to control configuration settings for different environments. When running tests the process.env.APP_ENV is set to test, and it will set the dialect to sqlite. Note that you will not have any data or data persistence, so you will need to populate it with all the data needed for your tests.
Include sqlite3
yarn add -D sqlite3
or
npm i -D sqlite3
Config
module.exports = {
database: {
name: 'dbname',
user: 'user',
password: 'password',
host: 'host',
// Use "sqlite" for "test", the connection settings above are ignored
dialect: process.env.APP_ENV === 'test' ? 'sqlite' : 'mysql',
},
};
Database/Sequelize
// get our config
const config = require('../config');
// ... code
const instance = new Sequelize(
config.database.name,
config.database.user,
config.database.password,
{
host: config.database.host,
// set the dialect, will be "sqlite" for "test"
dialect: config.database.dialect,
}
);
Test Class (Mocha)
const TestUtils = require('./lib/test-utils');
describe('Some Tests', () => {
let app = null;
// run before the tests start
before((done) => {
// Mock up our services
TestUtils.mock();
// these are instantiated after the mocking
app = require('../server');
// Populate redis data
TestUtils.populateRedis(() => {
// Populate db data
TestUtils.syncAndPopulateDatabase('test-data', () => {
done();
});
});
});
// run code after tests have completed
after(() => {
TestUtils.unMock();
});
describe('/my/route', () => {
it('should do something', (done) => {
return done();
});
});
});
Run Tests
APP_ENV=test ./node_modules/.bin/mocha
You could use ENV variables in other ways to set the dialect and connection parameters as well - the above is just an example based on what we have done with a lot of supporting code.

Answer 2

If you're not doing anything particularly complicated on the DB side, take a look at pg-mem:
https://swizec.com/blog/pg-mem-and-jest-for-smooth-integration-testing/
https://github.com/oguimbal/pg-mem
It's really cool in that it tests actual PG syntax and can pick up a bunch of errors that using a different DB or mock DB won't pick up. However, it's not a perfect implementation and missing a bunch of features (e.g. triggers, decent "not exists" handling, lots of functions) some of which are easy to work around with the hooks provided and some aren't.
For me, having the test DB initialized with the same schema initialization scripts as the real DB is a big win.