Creating a done function for Javascript unit testing

You want to make a test timeout if a callback is not called (similar to mocha's done function) but you are not using any framework. How can you achieve that?

// When test will timeout
var TEST_TIMEOUT_MS = 3000;

var done = (function () {
 // Create a timer that will fail on timeout
 var timer = setTimeout(function () {
 assert.ok(false, 'Test timeout');
 }, TEST_TIMEOUT_MS);

 // return done that will clear the timer and
 // avoid the timeout if called.
 return function () { clearTimeout(timer); };
})();

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