Add unit tests for parseDefaultThemeFromCountry function in geo module

src/utils/server/geo.test.ts

@@ -0,0 +1,119 @@
+import { getCountry } from 'countries-and-timezones';
+import { NextRequest } from 'next/server';
+import { describe, expect, it, vi } from 'vitest';
+
+import { parseDefaultThemeFromCountry } from './geo';
+
+vi.mock('countries-and-timezones');
+
+describe('parseDefaultThemeFromCountry', () => {
+  const mockRequest = (headers: Record<string, string | null> = {}, geo?: any): NextRequest =>
+    ({
+      headers: {
+        get: (key: string) => headers[key] || null,
+      },
+      geo,
+    }) as unknown as NextRequest;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it('should return light theme when no country code is found', () => {
+    const request = mockRequest();
+    expect(parseDefaultThemeFromCountry(request)).toBe('light');
+  });
+
+  it('should return light theme when country has no timezone info', () => {
+    const request = mockRequest({ 'x-vercel-ip-country': 'US' });
+    vi.mocked(getCountry).mockReturnValue(undefined);
+    expect(parseDefaultThemeFromCountry(request)).toBe('light');
+  });
+
+  it('should get country code from request.geo', () => {
+    const request = mockRequest({}, { country: 'US' });
+    vi.mocked(getCountry).mockReturnValue({
+      id: 'US',
+      name: 'United States',
+      timezones: ['America/New_York'],
+    });
+
+    // Set time to noon UTC
+    vi.setSystemTime(new Date('2025-02-14T12:00:00Z'));
+    expect(parseDefaultThemeFromCountry(request)).toBe('light');
+  });
+
+  it('should get country code from various headers', () => {
+    const headers = {
+      'x-vercel-ip-country': null,
+      'cf-ipcountry': 'CN',
+      'x-zeabur-ip-country': null,
+      'x-country-code': null,
+    };
+
+    const request = mockRequest(headers);
+    vi.mocked(getCountry).mockReturnValue({
+      id: 'CN',
+      name: 'China',
+      timezones: ['Asia/Shanghai'],
+    });
+
+    vi.setSystemTime(new Date('2025-02-14T20:00:00Z'));
+    expect(parseDefaultThemeFromCountry(request)).toBe('dark');
+  });
+
+  it('should return light theme during daytime hours (6-18)', () => {
+    const request = mockRequest({ 'x-vercel-ip-country': 'JP' });
+    vi.mocked(getCountry).mockReturnValue({
+      id: 'JP',
+      name: 'Japan',
+      timezones: ['Asia/Tokyo'],
+    });
+
+    // Set time to 3:00 AM UTC (12:00 JST)
+    vi.setSystemTime(new Date('2025-02-14T03:00:00Z'));
+    expect(parseDefaultThemeFromCountry(request)).toBe('light');
+  });
+
+  it('should return dark theme during nighttime hours', () => {
+    const request = mockRequest({ 'x-vercel-ip-country': 'JP' });
+    vi.mocked(getCountry).mockReturnValue({
+      id: 'JP',
+      name: 'Japan',
+      timezones: ['Asia/Tokyo'],
+    });
+
+    // Set time to 20:00 UTC (05:00 JST next day)
+    vi.setSystemTime(new Date('2025-02-14T20:00:00Z'));
+    expect(parseDefaultThemeFromCountry(request)).toBe('dark');
+  });
+
+  it('should return light theme for edge case at 6:00', () => {
+    const request = mockRequest({ 'x-vercel-ip-country': 'US' });
+    vi.mocked(getCountry).mockReturnValue({
+      id: 'US',
+      name: 'United States',
+      timezones: ['America/New_York'],
+    });
+
+    vi.setSystemTime(new Date('2025-02-14T11:00:00Z')); // 6:00 AM EST
+    expect(parseDefaultThemeFromCountry(request)).toBe('light');
+  });
+
+  it('should return dark theme for edge case at 18:00', () => {
+    const request = mockRequest({ 'x-vercel-ip-country': 'US' });
+    vi.mocked(getCountry).mockReturnValue({
+      id: 'US',
+      name: 'United States',
+      timezones: ['America/New_York'],
+    });
+
+    vi.setSystemTime(new Date('2025-02-14T23:00:00Z')); // 18:00 EST
+    expect(parseDefaultThemeFromCountry(request)).toBe('dark');
+  });
+});