Create mocha test/suite at runtime

mocha_runtime_tests.coffee

require('chai').should()

Mocha = require 'mocha'
Test = Mocha.Test
Suite = Mocha.Suite

mocha = new Mocha
suite = Suite.create mocha.suite, 'I am a dynamic suite'
suite.addTest new Test 'I am a dynamic test', ->
  true.should.equal true

mocha.run () ->
  console.log("done")

Thanks for this! Just wanted to add that if you don't want to use process.on events, you can use mocha runner events!

var Mocha = require('mocha');
var Chai = require('chai');
var Test = Mocha.Test;
var expect = Chai.expect;

var mochaInstance = new Mocha();
var suiteInstance = Mocha.Suite.create(mochaInstance.suite, 'Test Suite');

suiteInstance.addTest(new Test('testing tests', function(){
  expect(1).to.equal(2); // note testing 1 === 2 should fail
}))

var suiteRun = mochaInstance.run()
suiteRun.on('Mocha.Runner.constants.EVENT_SUITE_END', (code) => {
  process.exit(suiteRun.stats.failures > 0)
});