test(LanguageChart): add empty fallback coverage

Author: mayank200529

components/dashboard/LanguageChart.empty-fallback.test.tsx

@@ -0,0 +1,46 @@
+import { render, screen } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+
+import LanguageChart, { buildGradientStops } from './LanguageChart';
+
+class MockIntersectionObserver implements IntersectionObserver {
+  readonly root: Element | Document | null = null;
+  readonly rootMargin: string = '';
+  readonly thresholds: ReadonlyArray<number> = [];
+
+  disconnect = vi.fn();
+  observe = vi.fn();
+  takeRecords = vi.fn(() => []);
+  unobserve = vi.fn();
+}
+
+global.IntersectionObserver = MockIntersectionObserver;
+describe('LanguageChart empty fallback', () => {
+  it('renders fallback UI for empty languages array', () => {
+    render(<LanguageChart languages={[]} />);
+
+    expect(screen.getByText('Top Languages')).toBeInTheDocument();
+    expect(screen.getByText('No language data found')).toBeInTheDocument();
+  });
+
+  it('does not render language percentage markers in empty state', () => {
+    render(<LanguageChart languages={[]} />);
+
+    expect(screen.queryByText('%')).not.toBeInTheDocument();
+  });
+
+  it('keeps the fallback layout stable', () => {
+    const { container } = render(<LanguageChart languages={[]} />);
+
+    expect(container.firstChild).toBeInTheDocument();
+    expect(container.textContent).toContain('No language data found');
+  });
+
+  it('does not throw runtime error for empty languages array', () => {
+    expect(() => render(<LanguageChart languages={[]} />)).not.toThrow();
+  });
+
+  it('returns empty gradient stops for empty language data', () => {
+    expect(buildGradientStops([])).toBe('');
+  });
+});