test: verify buildCommitClock handles empty user metric logs (JhaSourav07#1688)

## Description

Added a test case for `buildCommitClock([])` with empty user metric logs
to verify the utility gracefully handles boundary inputs and bypasses 
writing undefined records to dashboard analytics.

## Testing
- Ran `npx vitest run lib/github.test.ts`
- Result: 73 passed ✅

Fixes JhaSourav07#1580 

## 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): ...`).
- [ ] 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.
- [ ] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [ ] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: RitvikaSavanna

app/components/CustomizeCTA.test.tsx

@@ -123,4 +123,126 @@ describe('CustomizeCTA', () => {
       expect(decorativeIcon).toBeTruthy();
     });
   });
+
+  describe('responsive breakpoints', () => {
+    it('renders all layout structure elements across viewports', () => {
+      const { container } = render(<CustomizeCTA />);
+
+      // Container with customization-studio id
+      const ctaSection = container.querySelector('#customization-studio');
+      expect(ctaSection).toBeTruthy();
+
+      // Outer rounded card container
+      const cardContainer = container.querySelector('[class*="rounded-[2rem]"]');
+      expect(cardContainer).toBeTruthy();
+
+      // Inner flex container that applies responsive layout
+      const flexContainer = container.querySelector('[class*="flex"]');
+      expect(flexContainer).toBeTruthy();
+
+      // Text content area
+      const textArea = container.querySelector('[class*="flex-1"]');
+      expect(textArea).toBeTruthy();
+
+      // CTA button shrink wrapper
+      const buttonWrapper = container.querySelector('[class*="shrink-0"]');
+      expect(buttonWrapper).toBeTruthy();
+    });
+
+    it('renders responsive text sizing from mobile to desktop', () => {
+      const { container } = render(<CustomizeCTA />);
+
+      const heading = screen.getByRole('heading', { level: 2 });
+
+      // Check that heading has responsive classes (text-2xl for mobile, md:text-3xl for desktop)
+      const headingClass = heading.getAttribute('class');
+      expect(headingClass).toMatch(/text-2xl/);
+      expect(headingClass).toMatch(/md:text-3xl/);
+    });
+
+    it('applies responsive gap and flex direction across breakpoints', () => {
+      const { container } = render(<CustomizeCTA />);
+
+      // Find the flex container with responsive gap and flex direction
+      // gap-8 for consistent spacing, md:flex-row for desktop layout
+      const flexContent = container.querySelector('[class*="flex"][class*="gap-8"]');
+      expect(flexContent).toBeTruthy();
+
+      const flexClass = flexContent?.getAttribute('class') || '';
+      expect(flexClass).toMatch(/gap-8/);
+      expect(flexClass).toMatch(/md:flex-row/);
+      expect(flexClass).toMatch(/flex-col/);
+    });
+
+    it('ensures button styling is responsive across viewports', () => {
+      const { container } = render(<CustomizeCTA />);
+
+      const button = container.querySelector('[class*="px-4"][class*="md:px-"]');
+      expect(button).toBeTruthy();
+
+      const buttonClass = button?.getAttribute('class') || '';
+      expect(buttonClass).toMatch(/px-4/);
+      expect(buttonClass).toMatch(/md:px-7/);
+    });
+
+    it('renders decorative background blobs that are hidden from interaction', () => {
+      const { container } = render(<CustomizeCTA />);
+
+      const blobs = container.querySelectorAll('[class*="blur-"]');
+      expect(blobs.length).toBeGreaterThanOrEqual(2);
+
+      blobs.forEach((blob) => {
+        const blobClass = blob.getAttribute('class') || '';
+        expect(blobClass).toMatch(/pointer-events-none/);
+      });
+    });
+
+    it('verifies navigation path is correct across all viewport sizes', () => {
+      render(<CustomizeCTA />);
+
+      const link = screen.getByRole('link');
+      expect(link.getAttribute('href')).toBe('/customize');
+
+      // Link should be visible and accessible regardless of viewport
+      expect(link).toHaveProperty('textContent');
+      expect(link.textContent).toContain('Open Customization Studio');
+    });
+
+    it('renders heading text layout appropriate for mobile and desktop', () => {
+      render(<CustomizeCTA />);
+
+      const eyebrowLabel = screen.getByText('Customization Studio');
+      const eyebrowClass = eyebrowLabel.getAttribute('class') || '';
+
+      // Verify eyebrow styling is consistent
+      expect(eyebrowClass).toMatch(/uppercase/);
+      expect(eyebrowClass).toMatch(/text-xs/);
+
+      const heading = screen.getByRole('heading', { level: 2 });
+      const headingClass = heading.getAttribute('class') || '';
+
+      // Heading has responsive text sizing
+      expect(headingClass).toMatch(/text-2xl/);
+      expect(headingClass).toMatch(/md:text-3xl/);
+
+      // Heading's parent container has responsive text alignment
+      const parentContainer = heading.closest('[class*="flex-1"]');
+      expect(parentContainer).toBeTruthy();
+
+      const parentClass = parentContainer?.getAttribute('class') || '';
+      expect(parentClass).toMatch(/text-center/);
+      expect(parentClass).toMatch(/md:text-left/);
+    });
+
+    it('renders content sections with responsive text alignment', () => {
+      const { container } = render(<CustomizeCTA />);
+
+      const contentArea = container.querySelector('[class*="text-center"][class*="md:text-left"]');
+      expect(contentArea).toBeTruthy();
+
+      const contentClass = contentArea?.getAttribute('class') || '';
+      expect(contentClass).toMatch(/text-center/);
+      expect(contentClass).toMatch(/md:text-left/);
+    });
+  });
 });

lib/github.test.ts

@@ -1279,6 +1279,15 @@ describe('buildCommitClock', () => {
     expect(result.every((item) => item.commits === 0)).toBe(true);
   });
 
+  it('returns defined dashboard analytics rows when user metric logs are empty', () => {
+    const result = buildCommitClock([]);
+
+    expect(result).toHaveLength(7);
+    expect(result.every((item) => typeof item.day === 'string')).toBe(true);
+    expect(result.every((item) => typeof item.commits === 'number')).toBe(true);
+    expect(result.every((item) => item.commits === 0)).toBe(true);
+  });
+
   it('always returns exactly 7 items', () => {
     const result = buildCommitClock([{ date: '2024-01-07', contributionCount: 1 }]);