How do you define Mocha tests programmatically and asynchronously?

Question

I'm trying to integrate some programmatically generated tests with the Mocha test framework in node.js.

var Promise = require('promise');

var resolved = Promise.resolve(true);

suite("Synchronously defined suite", function() {
  test("Synchronously defined test", function() {
    return resolved;
  });
});

defer(function() {
  suite("Asynch DEFINED test", function() {
    suiteSetup(function() {
      console.log("Asynch setupSuite running...");
    });

    test("Asynch Test", function() {
      console.log("Async test running...");
      return resolved;
    });
  });
});

function defer(fn) {
  console.log("Calling defer...");
  setTimeout(fn, 100);
}

When I execute this I get:

$ mocha --ui tdd nested-test.js 
Calling defer...


  Synchronously defined suite
    ✓ Synchronously defined test


  1 passing (4ms)

It seems that Mocha requires that all "suite" functions be executed synchronously at module load time - deferred calls seem to be (silently) ignored (or the program exits before calling them).

Answer 1

Here's what I've managed to come up with. It doesn't run underneath mocha, but as a stand-alone node program:

var Promise = require('promise');
var Mocha = require('mocha');

var resolved = Promise.resolve(true);
var rejected = Promise.reject(new Error("Failing test."));

defer(function() {
  console.log("Programmatic test suite creation.");
  var suite = new Mocha.Suite("Programatic Suite");
  var runner = new Mocha.Runner(suite);
  var reporter = new Mocha.reporters.Spec(runner);

  suite.addTest(new Mocha.Test("My test", function() {
    return resolved;
  }));

  suite.addTest(new Mocha.Test("My (failing) test", function() {
    return rejected;
  }));

  runner.run();
});

function defer(fn) {
  setTimeout(fn, 100);
}

When run it outputs:

$ node deferred-test.js 
Programmatic test suite creation.

Programatic Suite
  ✓ My test
  1) My (failing) test

  1 passing (7ms)
  1 failing

  1) Programatic Suite My (failing) test:
     Error: Failing test.
      at Object.<anonymous> (deferred-test.js:5:31)
      at node.js:935:3

I'd like to be able to include this test among all the (statically defined) mocha-run test suites in my application, however.