test(validate-user): add empty input fallback coverage

Author: chavanGaneshDatta

services/github/validate-user.empty-fallback.test.ts

@@ -0,0 +1,63 @@
+// services/github/validate-user.empty-fallback.test.ts
+
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+vi.mock('../../lib/github', () => ({
+  fetchUserProfile: vi.fn(),
+}));
+
+import { fetchUserProfile } from '../../lib/github';
+import { gitHubUserValidator } from './validate-user';
+
+describe('GitHubUserValidator Empty & Missing Input Fallbacks', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    gitHubUserValidator.reset();
+  });
+
+  it('throws for empty usernames', async () => {
+    vi.mocked(fetchUserProfile).mockRejectedValue(new Error('User not found'));
+
+    await expect(gitHubUserValidator.validateUser('')).rejects.toThrow('Cache key cannot be empty');
+  });
+
+  it('throws for whitespace-only usernames', async () => {
+    vi.mocked(fetchUserProfile).mockRejectedValue(new Error('User not found'));
+
+    await expect(gitHubUserValidator.validateUser('     ')).rejects.toThrow(
+      'Cache key cannot be empty'
+    );
+  });
+
+  it('caches negative results for missing users', async () => {
+    vi.mocked(fetchUserProfile).mockRejectedValue(new Error('User not found'));
+
+    const first = await gitHubUserValidator.validateUser('missing-user');
+    const second = await gitHubUserValidator.validateUser('missing-user');
+
+    expect(first).toBe(false);
+    expect(second).toBe(false);
+
+    expect(fetchUserProfile).toHaveBeenCalledTimes(1);
+  });
+
+  it('returns cached result for usernames with different casing and spacing', async () => {
+    vi.mocked(fetchUserProfile).mockResolvedValue({} as never);
+
+    const first = await gitHubUserValidator.validateUser('Ganesh');
+    const second = await gitHubUserValidator.validateUser('  ganesh  ');
+
+    expect(first).toBe(true);
+    expect(second).toBe(true);
+
+    expect(fetchUserProfile).toHaveBeenCalledTimes(1);
+  });
+
+  it('rethrows unexpected service errors instead of masking them', async () => {
+    vi.mocked(fetchUserProfile).mockRejectedValue(new Error('GitHub API unavailable'));
+
+    await expect(gitHubUserValidator.validateUser('ganesh')).rejects.toThrow(
+      'GitHub API unavailable'
+    );
+  });
+});