refactor: executor protocol, fallback, debounce

web/src/lib/core/debounce.test.ts

@@ -0,0 +1,38 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { debounce } from "./debounce";
+
+afterEach(() => {
+	vi.useRealTimers();
+});
+
+describe("debounce", () => {
+	it("coalesces calls until the deadline", () => {
+		vi.useFakeTimers();
+		const fn = vi.fn();
+		const debounced = debounce(fn, 200);
+
+		debounced();
+		vi.advanceTimersByTime(199);
+		debounced();
+		vi.advanceTimersByTime(199);
+		expect(fn).not.toHaveBeenCalled();
+
+		vi.advanceTimersByTime(1);
+		expect(fn).toHaveBeenCalledTimes(1);
+	});
+
+	it("cancels a pending call and can be scheduled again", () => {
+		vi.useFakeTimers();
+		const fn = vi.fn();
+		const debounced = debounce(fn, 200);
+
+		debounced();
+		debounced.cancel();
+		vi.advanceTimersByTime(200);
+		expect(fn).not.toHaveBeenCalled();
+
+		debounced();
+		vi.advanceTimersByTime(200);
+		expect(fn).toHaveBeenCalledTimes(1);
+	});
+});