add unit tests

tests/hooks/useCooldownTimer.test.tsx

@@ -0,0 +1,64 @@
+import { act } from 'react';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { useCooldownTimer } from '../../src/hooks/useCooldownTimer';
+import { renderHook } from '../helpers/renderHook';
+
+describe('useCooldownTimer', () => {
+    beforeEach(() => {
+        vi.useFakeTimers();
+    });
+
+    afterEach(() => {
+        vi.useRealTimers();
+    });
+
+    it('decrements cooldown every second while enabled', () => {
+        const { result } = renderHook(() => useCooldownTimer(2, true));
+
+        expect(result.current.cooldown).toBe(2);
+
+        act(() => {
+            vi.advanceTimersByTime(1000);
+        });
+        expect(result.current.cooldown).toBe(1);
+
+        act(() => {
+            vi.advanceTimersByTime(1000);
+        });
+        expect(result.current.cooldown).toBe(0);
+    });
+
+    it('does not decrement when disabled', () => {
+        const { result } = renderHook(() => useCooldownTimer(2, false));
+
+        act(() => {
+            vi.advanceTimersByTime(3000);
+        });
+
+        expect(result.current.cooldown).toBe(2);
+    });
+
+    it('startCooldown floors values and clamps negatives', () => {
+        const { result } = renderHook(() => useCooldownTimer(0, true));
+
+        act(() => {
+            result.current.startCooldown(2.8);
+        });
+        expect(result.current.cooldown).toBe(2);
+
+        act(() => {
+            result.current.startCooldown(-4);
+        });
+        expect(result.current.cooldown).toBe(0);
+    });
+
+    it('stays at zero when already expired', () => {
+        const { result } = renderHook(() => useCooldownTimer(0, true));
+
+        act(() => {
+            vi.advanceTimersByTime(2000);
+        });
+
+        expect(result.current.cooldown).toBe(0);
+    });
+});