Tone.js/test/signal/WaveShaper.js

import Offline from "helper/Offline";
import Basic from "helper/Basic";
import WaveShaper from "Tone/signal/WaveShaper";
import Signal from "Tone/signal/Signal";
import ConstantOutput from "helper/ConstantOutput";

describe("WaveShaper", function(){

	Basic(WaveShaper);

	describe("Construction Options", function(){

		it("can be constructed with an array", function(){
			var waveshaper = new WaveShaper([1, 2, 3, 4, 5, 6]);
			expect(waveshaper.curve[0]).to.equal(1);
			expect(waveshaper.curve[2]).to.equal(3);
		});

		it("can be constructed with a mapping function", function(){
			var waveshaper = new WaveShaper(function(){
				return -2;
			});
			expect(waveshaper.curve[0]).to.equal(-2);
			expect(waveshaper.curve[1]).to.equal(-2);
		});

		it("can be constructed with a length and then set with a map", function(){
			var waveshaper = new WaveShaper(2048).setMap(function(){
				return 10;
			});
			expect(waveshaper.curve.length).to.equal(2048);
			expect(waveshaper.curve[0]).to.equal(10);
			expect(waveshaper.curve[1]).to.equal(10);
		});

		it("can be set to oversample", function(){
			var waveshaper = new WaveShaper();
			expect(waveshaper.oversample).to.equal("none");
			waveshaper.oversample = "2x";
			expect(waveshaper.oversample).to.equal("2x");
			expect(function(){
				waveshaper.oversample = "3x";
			}).to.throw(Error);
		});
		
	});

	describe("Logic", function(){

		it("shapes the output of the incoming signal", function(){
			return ConstantOutput(function(){
				var signal = new Signal(1);
				var waveshaper = new WaveShaper([-10, -10, -10]);
				signal.connect(waveshaper);
				waveshaper.toMaster();
			}, -10);
		});

		it("outputs the last curve value when the input is above 1", function(){
			return ConstantOutput(function(){
				var signal = new Signal(10);
				var waveshaper = new WaveShaper([-20, 20]);
				signal.connect(waveshaper);
				waveshaper.toMaster();
			}, 20);
		});

		it("outputs the first curve value when the input is below -1", function(){
			return ConstantOutput(function(){
				var signal = new Signal(-1);
				var waveshaper = new WaveShaper([-20, 20]);
				signal.connect(waveshaper);
				waveshaper.toMaster();
			}, -20);
		});

		it("maps the input through the waveshaping curve", function(){
			return Offline(function(){
				var signal = new Signal(-1);
				var waveshaper = new WaveShaper(function(input){
					return input * 2;
				});
				signal.connect(waveshaper);
				waveshaper.toMaster();
				signal.setValueAtTime(-1, 0);
				signal.linearRampToValueAtTime(1, 1);
			}, 1).then(function(buffer){
				buffer.forEach(function(sample, time){
					expect(sample).to.be.closeTo(2 * ((time * 2) - 1), 0.005);
				});
			});
		});

	});
});