test(i18n): add Japanese badge label coverage

Author: Vishvadharman

lib/i18n/languages/ja.test.ts

@@ -0,0 +1,65 @@
+import { describe, expect, it } from 'vitest';
+import { getLabels, labels } from '../badgeLabels';
+
+const requiredKeys = [
+  'CURRENT_STREAK',
+  'ANNUAL_SYNC_TOTAL',
+  'PEAK_STREAK',
+  'COMMITS_THIS_MONTH',
+  'VS_LAST_MONTH',
+] as const;
+
+const expectedJapaneseLabels = {
+  CURRENT_STREAK: '現在のストリーク',
+  ANNUAL_SYNC_TOTAL: '年間合計',
+  PEAK_STREAK: '最高ストリーク',
+  COMMITS_THIS_MONTH: '今月のコミット数',
+  VS_LAST_MONTH: '先月比',
+};
+
+function renderMockBadge(lang: string) {
+  const badgeLabels = getLabels(lang);
+
+  return `
+    <svg role="img" data-lang="${lang}">
+      <text>${badgeLabels.CURRENT_STREAK}</text>
+      <text>${badgeLabels.ANNUAL_SYNC_TOTAL}</text>
+      <text>${badgeLabels.PEAK_STREAK}</text>
+      <text>${badgeLabels.COMMITS_THIS_MONTH}</text>
+      <text>${badgeLabels.VS_LAST_MONTH}</text>
+    </svg>
+  `;
+}
+
+describe('Japanese badge labels', () => {
+  it('includes the ja language key in the labels dictionary', () => {
+    expect(labels.ja).toBeDefined();
+  });
+
+  it('returns the exact Japanese translation mapping through getLabels', () => {
+    expect(getLabels('ja')).toEqual(expectedJapaneseLabels);
+  });
+
+  it('returns the Japanese mapping when lang code casing differs', () => {
+    expect(getLabels('JA')).toEqual(expectedJapaneseLabels);
+  });
+
+  it('sets every required Japanese label to a non-empty string', () => {
+    const japaneseLabels = getLabels('ja');
+
+    for (const key of requiredKeys) {
+      expect(typeof japaneseLabels[key]).toBe('string');
+      expect(japaneseLabels[key].trim().length).toBeGreaterThan(0);
+    }
+  });
+
+  it('renders a mock SVG with Japanese translated labels', () => {
+    const svg = renderMockBadge('ja');
+
+    expect(svg).toContain('data-lang="ja"');
+
+    for (const value of Object.values(expectedJapaneseLabels)) {
+      expect(svg).toContain(value);
+    }
+  });
+});