Tone.js/test/helper/ConstantOutput.js

define(["helper/Offline"], function (Offline) {
	return function(callback, value, threshold){
		if (typeof threshold === "undefined"){
			threshold = 0.01;
		}
		return Offline(callback).then(function(buffer){
			expect(buffer.value()).to.be.closeTo(value, threshold);
		});
	};
});