From 6f4f53d0eaaa4a49401f03796b7694af5ae54ce3 Mon Sep 17 00:00:00 2001
From: Ibrahim Suleiman <suleimanonnet@gmail.com>
Date: Wed, 13 May 2026 19:48:41 +0100
Subject: [PATCH] test: add leap-year cases for parseToTimestamp

Cover calendar add across Feb 29, 1y from leap day, and 1y vs naive
365d across a leap boundary. Document getFutureTimeWithoutLeap drift.
---
 src/utils/time.util.spec.ts | 65 +++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 src/utils/time.util.spec.ts

diff --git a/src/utils/time.util.spec.ts b/src/utils/time.util.spec.ts
new file mode 100644
index 0000000..e27c528
--- /dev/null
+++ b/src/utils/time.util.spec.ts
@@ -0,0 +1,65 @@
+import {
+  getFutureTimeWithoutLeap,
+  parseToTimestamp,
+} from './time.util';
+
+describe('parseToTimestamp', () => {
+  afterEach(() => {
+    jest.useRealTimers();
+  });
+
+  it('adds 1 day across Feb 29 in a leap year (UTC anchor)', () => {
+    jest.useFakeTimers({ doNotFake: ['nextTick'] });
+    jest.setSystemTime(new Date('2024-02-28T12:00:00.000Z'));
+
+    const ts = parseToTimestamp('1d');
+    expect(new Date(ts).toISOString()).toBe('2024-02-29T12:00:00.000Z');
+  });
+
+  it('adds 1 day from Feb 29 to Mar 1 in a leap year', () => {
+    jest.useFakeTimers({ doNotFake: ['nextTick'] });
+    jest.setSystemTime(new Date('2024-02-29T12:00:00.000Z'));
+
+    const ts = parseToTimestamp('1d');
+    expect(new Date(ts).toISOString()).toBe('2024-03-01T12:00:00.000Z');
+  });
+
+  it('adds 1 calendar year from leap day (not fixed 365d)', () => {
+    jest.useFakeTimers({ doNotFake: ['nextTick'] });
+    jest.setSystemTime(new Date('2024-02-29T12:00:00.000Z'));
+
+    const ts = parseToTimestamp('1y');
+    expect(new Date(ts).toISOString()).toBe('2025-02-28T12:00:00.000Z');
+  });
+
+  it('1y across a leap year is one day after naive 365 × 24h from Mar 1 anchor', () => {
+    jest.useFakeTimers({ doNotFake: ['nextTick'] });
+    jest.setSystemTime(new Date('2023-03-01T12:00:00.000Z'));
+
+    const calendarOneYear = parseToTimestamp('1y');
+    const naive365Days = Date.now() + 365 * 24 * 60 * 60 * 1000;
+
+    expect(calendarOneYear - naive365Days).toBe(24 * 60 * 60 * 1000);
+    expect(new Date(calendarOneYear).toISOString()).toBe(
+      '2024-03-01T12:00:00.000Z',
+    );
+  });
+});
+
+describe('getFutureTimeWithoutLeap', () => {
+  afterEach(() => {
+    jest.useRealTimers();
+  });
+
+  it('uses exactly 365d per year (differs from calendar year over leap boundary)', () => {
+    jest.useFakeTimers({ doNotFake: ['nextTick'] });
+    jest.setSystemTime(new Date('2023-03-01T12:00:00.000Z'));
+
+    const withoutLeap = getFutureTimeWithoutLeap('1y');
+    const calendar = parseToTimestamp('1y');
+
+    expect(withoutLeap).toBe(Date.now() + 365 * 24 * 60 * 60 * 1000);
+    expect(new Date(withoutLeap).toISOString()).toBe('2024-02-29T12:00:00.000Z');
+    expect(calendar - withoutLeap).toBe(24 * 60 * 60 * 1000);
+  });
+});