mocha docker postgres

mocha testhelper for integration tests with postgres using docker.

Usage:

Ensure Docker is installed and the postgres docker image has been pulled. e.g. docker pull postgres

require('mocha-docker-postgres'); // will patch the mocha Context prototype

var someModule = require('../someModule');

describe('some module', function () {
    var instanceOfSomeModule;
    before(function () {
        this.timeout(10000); // you may need to bump the timeout for this block
        return this.dockerPostgres();
    });
    before(function () {
        // create an instance of someModule where the connection string
        // to the created postgres instance is passed along as an option
        instanceOfSomeModule = someModule({
            conString: this.conString
        });
    });

    it('should ...', function () {
        return expect(instanceOfSomeModule.whatEver, 'to ...');
    });
});

A call to this.dockerPostgres() will start a docker container (unless we already have one that fits) , and will set the value this.conString to the postgres url needed to connect to that database.

The method returns a promise, and that promise will not resolve until the postgres database is ready to accept connections.

You get a completely fresh database after each call to this.dockerPostgres so you will need to run your migrations in a before hook after that.

If you want to have a completely fresh database for each test, you can make the before hook into a beforeEach. It will reuse the same postgres container, but create new databases for each invocation of the method - which makes it a lot less time consuming.

On my developer work station it takes about 4 seconds for postgres to start up, and that is only done once per test run.

Running on OSX

On all platforms elevated privileges are required to bind to TCP ports < 1024 and to run the docker deamon. On OSX brew install docker just installs the CLI In order to get docker running use brew cask install docker. Then open the Docker application and allow privileged execution when prompted.