fix(console): test debounce and throttle utilities (#6982)

Fix implementation of debounce and throttle utilities, including the
addition of tests.

apps/wing-console/packages/utilities/src/debounce.test.ts

@@ -0,0 +1,24 @@
+import { afterEach, beforeEach, expect, test, vi } from "vitest";
+
+import { debounce } from "./debounce.js";
+
+beforeEach(() => {
+  vi.useFakeTimers();
+});
+
+afterEach(() => {
+  vi.useRealTimers();
+});
+
+test("debounces calls", () => {
+  const function_ = vi.fn();
+  const debounced = debounce(function_, 1);
+
+  debounced();
+  debounced();
+  debounced();
+  expect(function_).toHaveBeenCalledTimes(0);
+
+  vi.advanceTimersByTime(1);
+  expect(function_).toHaveBeenCalledTimes(1);
+});

apps/wing-console/packages/utilities/src/debounce.ts

@@ -1,25 +1,16 @@
 export function debounce<T extends (...arguments_: any[]) => void>(
   function_: T,
   wait: number,
-  immediate: boolean = false,
 ): (...arguments_: Parameters<T>) => void {
   let timeout: NodeJS.Timeout | undefined;
 
   return (...arguments_: Parameters<T>): void => {
-    const later = () => {
-      timeout = undefined;
-      if (!immediate) {
-        function_(...arguments_);
-      }
-    };
-
-    const callNow = immediate && !timeout;
-
     clearTimeout(timeout);
-    timeout = setTimeout(later, wait);
+    timeout = setTimeout(() => {
+      timeout = undefined;
 
-    if (callNow) {
+      // Trailing call.
       function_(...arguments_);
-    }
+    }, wait);
   };
 }

apps/wing-console/packages/utilities/src/throttle.test.ts

@@ -0,0 +1,39 @@
+import { afterEach, beforeEach, expect, test, vi } from "vitest";
+
+import { throttle } from "./throttle.js";
+
+beforeEach(() => {
+  vi.useFakeTimers();
+});
+
+afterEach(() => {
+  vi.useRealTimers();
+});
+
+test("throttles calls", () => {
+  const function_ = vi.fn();
+  const throttled = throttle(function_, 100);
+
+  throttled();
+  throttled();
+  throttled();
+  expect(function_).toHaveBeenCalledTimes(1);
+
+  vi.advanceTimersByTime(99);
+  throttled();
+  throttled();
+  throttled();
+  expect(function_).toHaveBeenCalledTimes(1);
+
+  vi.advanceTimersByTime(1);
+  throttled();
+  throttled();
+  throttled();
+  expect(function_).toHaveBeenCalledTimes(2);
+
+  vi.advanceTimersByTime(100);
+  throttled();
+  throttled();
+  throttled();
+  expect(function_).toHaveBeenCalledTimes(3);
+});

apps/wing-console/packages/utilities/src/throttle.ts

@@ -2,10 +2,10 @@ export function throttle<T extends (...arguments_: any[]) => void>(
   function_: T,
   timeFrame: number,
 ): (...arguments_: Parameters<T>) => void {
-  let lastTime = 0;
+  let lastTime: number | undefined;
   return (...arguments_) => {
     const now = Date.now();
-    if (now - lastTime >= timeFrame) {
+    if (lastTime === undefined || now - lastTime >= timeFrame) {
       function_(...arguments_);
       lastTime = now;
     }