three.js/test/unit/core/Clock.js

/**
 * @author simonThiele / https://github.com/simonThiele
 */

module( "Clock" );

function mockPerformance() {
	self.performance = {
		deltaTime: 0,

		next: function( delta ) {
			this.deltaTime += delta;
		},

		now: function() {
			return this.deltaTime;
		}
	};
}

test( "clock with performance", function() {
	mockPerformance();

	var clock = new THREE.Clock();

	clock.start();

	self.performance.next(123);
	ok( clock.getElapsedTime() === 0.123 , "okay");

	self.performance.next(100);
	ok( clock.getElapsedTime() === 0.223 , "okay");

	clock.stop();

	self.performance.next(1000);
	ok( clock.getElapsedTime() === 0.223 , "don't update time if the clock was stopped");
});