tone/Tone/component/filter/FeedbackCombFilter.test.ts

A Web Audio framework for making interactive music in the browser.

import { expect } from "chai";
import { FeedbackCombFilter } from "./FeedbackCombFilter";
import { BasicTests } from "test/helper/Basic";
import { PassAudio } from "test/helper/PassAudio";
import { Offline } from "test/helper/Offline";
import { Signal } from "Tone/signal";

describe("FeedbackCombFilter", () => {

	BasicTests(FeedbackCombFilter);

	context("Comb Filtering", () => {

		it("can be constructed with an object", () => {
			const fbcf = new FeedbackCombFilter({
				delayTime: 0.2,
				resonance: 0.3,
			});
			expect(fbcf.delayTime.value).to.be.closeTo(0.2, 0.001);
			expect(fbcf.resonance.value).to.be.closeTo(0.3, 0.001);
			fbcf.dispose();
		});

		it("can be get and set through object", () => {
			const fbcf = new FeedbackCombFilter();
			fbcf.set({
				delayTime: 0.2,
				resonance: 0.3,
			});
			const values = fbcf.get();
			expect(values.delayTime).to.be.closeTo(0.2, 0.001);
			expect(values.resonance).to.be.closeTo(0.3, 0.001);
			fbcf.dispose();
		});

		it("passes the incoming signal through", () => {
			return PassAudio(input => {
				const fbcf = new FeedbackCombFilter({
					delayTime: 0.0,
					resonance: 0,
				}).toDestination();
				input.connect(fbcf);
			});
		});

		it("can delay by the delayTime", () => {
			return Offline(() => {
				const fbcf = new FeedbackCombFilter({
					delayTime: 0.1,
					resonance: 0,
				}).toDestination();
				const sig = new Signal(0).connect(fbcf);
				sig.setValueAtTime(1, 0);
			}, 0.2).then(buffer => {
				expect(buffer.getValueAtTime(0)).to.equal(0);
				expect(buffer.getValueAtTime(0.999)).to.equal(0);
				expect(buffer.getValueAtTime(0.101)).to.equal(1);
				expect(buffer.getValueAtTime(0.15)).to.equal(1);
			});
		});

		it("can delay with feedback", () => {
			return Offline(() => {
				const fbcf = new FeedbackCombFilter({
					delayTime: 0.1,
					resonance: 0.5,
				}).toDestination();
				const sig = new Signal(0).connect(fbcf);
				sig.setValueAtTime(1, 0);
				sig.setValueAtTime(0, 0.1);
			}, 0.4).then(buffer => {
				expect(buffer.getValueAtTime(0)).to.equal(0);
				expect(buffer.getValueAtTime(0.101)).to.equal(1);
				expect(buffer.getValueAtTime(0.201)).to.equal(0.5);
				expect(buffer.getValueAtTime(0.301)).to.equal(0.25);
			});
		});
	});
});