first commit

tests/dateFilter.test.ts

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+import { describe, it, expect } from 'vitest';
+import {
+  formatDateForDb,
+  getAdjustedDateRange,
+  getEffectiveCycleDay,
+  getEffectiveDate,
+} from '../utils/dateFilter.ts';
+
+describe('dateFilter', () => {
+  it('uses the previous day before 17:00 WIB', () => {
+    const referenceDate = new Date('2026-06-09T08:30:00.000Z'); // 15:30 WIB
+
+    const effectiveDate = getEffectiveDate(referenceDate);
+
+    expect(formatDateForDb(effectiveDate)).toBe('2026-06-08');
+    expect(getEffectiveCycleDay('2026-06-01', referenceDate)).toBe(7);
+    expect(getAdjustedDateRange('2026-06-09', '2026-06-09', referenceDate)).toEqual({
+      start: '2026-06-08',
+      end: '2026-06-08',
+    });
+  });
+
+  it('uses the current day at or after 17:00 WIB', () => {
+    const referenceDate = new Date('2026-06-09T10:30:00.000Z'); // 17:30 WIB
+
+    const effectiveDate = getEffectiveDate(referenceDate);
+
+    expect(formatDateForDb(effectiveDate)).toBe('2026-06-09');
+    expect(getEffectiveCycleDay('2026-06-01', referenceDate)).toBe(8);
+    expect(getAdjustedDateRange('2026-06-09', '2026-06-09', referenceDate)).toEqual({
+      start: '2026-06-09',
+      end: '2026-06-09',
+    });
+  });
+});