test: add unit tests for AchievementsSkeleton Component (JhaSourav07#1768)

## Description

Fixes JhaSourav07#1013 

## Pillar

- [ ] 🎨 Pillar 1 — New Theme Design
- [ ] 📐 Pillar 2 — Geometric SVG Improvement
- [ ] 🕐 Pillar 3 — Timezone Logic Optimization
- [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview

## Checklist before requesting a review:

- [x] I have read the `CONTRIBUTING.md` file.
- [x] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME`).
- [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will fail otherwise).
- [x] My commits follow the Conventional Commits format (e.g.,
`feat(themes): ...`, `fix(calculate): ...`).
- [x] I have updated `README.md` if I added a new theme or URL
parameter.
- [x] I have started the repo.
- [x] I have made sure that i have only one commit to merge in this PR.
- [x] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

components/dashboard/AchievementsSkeleton.test.tsx

@@ -0,0 +1,27 @@
+import { render, screen } from '@testing-library/react';
+import { describe, it, expect } from 'vitest';
+
+import AchievementsSkeleton from './AchievementsSkeleton';
+
+describe('AchievementsSkeleton', () => {
+  it(' renders without crashing', () => {
+    expect(render(<AchievementsSkeleton />));
+  });
+  it(' renders exactly 4 skeleton cells.', () => {
+    render(<AchievementsSkeleton />);
+    const cells = screen.getAllByTestId('skeleton-cell');
+    expect(cells).toHaveLength(4);
+  });
+  it('each cell has the shimmer class.', () => {
+    render(<AchievementsSkeleton />);
+    const cells = screen.getAllByTestId('skeleton-cell');
+
+    cells.forEach((cell) => {
+      expect(cell.classList).toContain('shimmer');
+    });
+  });
+  it('uses a grid-cols-2 layout.', () => {
+    const { container } = render(<AchievementsSkeleton />);
+    expect(container.querySelector('.grid-cols-2')).toBeTruthy();
+  });
+});

components/dashboard/AchievementsSkeleton.tsx

@@ -2,7 +2,11 @@ export default function AchievementsSkeleton() {
   return (
     <div className="grid grid-cols-2 gap-2">
       {[...Array(4)].map((_, i) => (
-        <div key={i} className="h-16 shimmer rounded border border-white/5" />
+        <div
+          key={i}
+          className="h-16 shimmer rounded border border-white/5"
+          data-testid="skeleton-cell"
+        />
       ))}
     </div>
   );