refactor: reorganize shared/lib into per-function subfolders

src/shared/lib/utils/formatDate/formatDate.test.ts

@@ -0,0 +1,47 @@
+import { formatYearRange } from './formatDate';
+
+describe('formatYearRange', () => {
+  describe('Success Paths', () => {
+    it('formats a date range within the same year', () => {
+      const start = '2024-01-01 12:00:00.000Z';
+      const end = '2024-12-31 12:00:00.000Z';
+      expect(formatYearRange(start, end)).toBe('2024');
+    });
+
+    it('formats a range between different years', () => {
+      const start = '2021-05-15 12:00:00.000Z';
+      const end = '2024-03-20 12:00:00.000Z';
+      expect(formatYearRange(start, end)).toBe('2021 — 2024');
+    });
+
+    it('formats a range with null end date as "Present"', () => {
+      const start = '2022-08-01 12:00:00.000Z';
+      const end = null;
+      expect(formatYearRange(start, end)).toBe('2022 — Present');
+    });
+  });
+
+  describe('Error & Edge Cases', () => {
+    it('throws if start date is invalid', () => {
+      const start = 'not-a-date';
+      const end = '2024-01-01';
+      expect(() => formatYearRange(start, end)).toThrow('Invalid start date');
+    });
+
+    it('throws if end date is provided but invalid', () => {
+      const start = '2024-01-01';
+      const end = 'invalid';
+      expect(() => formatYearRange(start, end)).toThrow('Invalid end date');
+    });
+
+    it('throws if start year is after end year', () => {
+      const start = '2024-01-01';
+      const end = '2020-01-01';
+      expect(() => formatYearRange(start, end)).toThrow('Start year cannot be after end year');
+    });
+
+    it('handles empty strings by throwing', () => {
+      expect(() => formatYearRange('', null)).toThrow('Invalid start date');
+    });
+  });
+});