Tone.js/test/signal/Subtract.js

define(["helper/ConstantOutput", "Tone/signal/Subtract", "helper/Basic", 
	"Test", "Tone/source/Oscillator", "Tone/signal/Signal"], 
	function (ConstantOutput, Subtract, Basic, Test, Oscillator, Signal) {

	describe("Subtract", function(){

		Basic(Subtract);

		context("Subtraction", function(){

			it("handles input and output connections", function(){
				var subtract = new Subtract();
				Test.connect(subtract, 0);
				Test.connect(subtract, 1);
				subtract.connect(Test);
				subtract.dispose();
			});

			it("correctly subtracts a signal and a number", function(){
				return ConstantOutput(function(){
					var signal = new Signal(0);
					var sub = new Subtract(3);
					signal.connect(sub);
					sub.toMaster();
				}, -3); 
			});

			it("can set the scalar value after construction", function(){
				return ConstantOutput(function(){
					var signal = new Signal(-2);
					var sub = new Subtract(0);
					sub.value = 4;
					signal.connect(sub);
					sub.toMaster();
				}, -6); 
			});

			it("can handle negative values", function(){
				return ConstantOutput(function(){
					var signal = new Signal(4);
					var sub = new Subtract(-2);
					signal.connect(sub);
					sub.toMaster();
				}, 6); 
			});

			it("can subtract two signals", function(){
				return ConstantOutput(function(){
					var sigA = new Signal(1);
					var sigB = new Signal(4);
					var sub = new Subtract();
					sigA.connect(sub, 0, 0);
					sigB.connect(sub, 0, 1);
					sub.toMaster();
				}, -3); 
			});
		});
	});
});