test(contributors): add timezone boundaries test suite (JhaSourav07#2860) (JhaSourav07#3011)

Co-authored-by: Sourav Jha <25BCS12964@cuchd.in>

Author: boss477

app/contributors/page.timezone-boundaries.test.tsx

@@ -0,0 +1,122 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import ContributorsPage from './page';
+import '@testing-library/jest-dom';
+
+describe('ContributorsPage - Timezone Boundaries & Calendar Alignment', () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('verifies standard timestamp formatting in rate limit message', async () => {
+    const timestamp = 1704067200; // 2024-01-01T00:00:00.000Z
+    global.fetch = vi.fn(() =>
+      Promise.resolve({
+        ok: false,
+        status: 403,
+        headers: {
+          get: (name: string) => {
+            if (name === 'x-ratelimit-remaining') return '0';
+            if (name === 'x-ratelimit-reset') return String(timestamp);
+            return null;
+          },
+        },
+        json: async () => [],
+      })
+    ) as unknown as typeof fetch;
+
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    const element = await ContributorsPage();
+    // Element renders fallback UI because of the API rate limit error, fetch fails gracefully
+    expect(element).toBeDefined();
+    expect(consoleSpy).toHaveBeenCalledWith(
+      'Failed to fetch contributors:',
+      expect.objectContaining({
+        message: expect.stringContaining('Please try again after 2024-01-01T00:00:00.000Z.'),
+      })
+    );
+  });
+
+  it('verifies timezone/calendar alignment during leap year boundaries', async () => {
+    const timestamp = 1709164800; // 2024-02-29T00:00:00.000Z (Leap day)
+    global.fetch = vi.fn(() =>
+      Promise.resolve({
+        ok: false,
+        status: 403,
+        headers: {
+          get: (name: string) => {
+            if (name === 'x-ratelimit-remaining') return '0';
+            if (name === 'x-ratelimit-reset') return String(timestamp);
+            return null;
+          },
+        },
+        json: async () => [],
+      })
+    ) as unknown as typeof fetch;
+
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    await ContributorsPage();
+    expect(consoleSpy).toHaveBeenCalledWith(
+      'Failed to fetch contributors:',
+      expect.objectContaining({
+        message: expect.stringContaining('Please try again after 2024-02-29T00:00:00.000Z.'),
+      })
+    );
+  });
+
+  it('verifies timezone/calendar alignment during year-end boundary rollovers', async () => {
+    const timestamp = 1798761599; // 2026-12-31T23:59:59.000Z
+    global.fetch = vi.fn(() =>
+      Promise.resolve({
+        ok: false,
+        status: 403,
+        headers: {
+          get: (name: string) => {
+            if (name === 'x-ratelimit-remaining') return '0';
+            if (name === 'x-ratelimit-reset') return String(timestamp);
+            return null;
+          },
+        },
+        json: async () => [],
+      })
+    ) as unknown as typeof fetch;
+
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    await ContributorsPage();
+    expect(consoleSpy).toHaveBeenCalledWith(
+      'Failed to fetch contributors:',
+      expect.objectContaining({
+        message: expect.stringContaining('Please try again after 2026-12-31T23:59:59.000Z.'),
+      })
+    );
+  });
+
+  it('handles invalid non-numeric or empty rate limit reset headers gracefully without throwing formatter exceptions', async () => {
+    global.fetch = vi.fn(() =>
+      Promise.resolve({
+        ok: false,
+        status: 429,
+        headers: {
+          get: (name: string) => {
+            if (name === 'x-ratelimit-reset') return 'invalid-timestamp';
+            return null;
+          },
+        },
+        json: async () => [],
+      })
+    ) as unknown as typeof fetch;
+
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+    await ContributorsPage();
+    // It should omit the date reset message entirely when timestamp is invalid
+    expect(consoleSpy).toHaveBeenCalledWith(
+      'Failed to fetch contributors:',
+      expect.objectContaining({
+        message: 'GitHub API rate limit exceeded. Please try again later.',
+      })
+    );
+  });
+});