From efef8eb70293bdd28397e7dec81b4f86f16523cb Mon Sep 17 00:00:00 2001
From: kenjis <kenji.uui@gmail.com>
Date: Mon, 20 Jun 2022 08:02:45 +0900
Subject: [PATCH] fix: getAge() calculation

---
 system/I18n/Time.php           |  9 +++++----
 tests/system/I18n/TimeTest.php | 24 ++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/system/I18n/Time.php b/system/I18n/Time.php
index 659a0a252d..77141a840e 100644
--- a/system/I18n/Time.php
+++ b/system/I18n/Time.php
@@ -452,7 +452,7 @@ class Time extends DateTime
     }
 
     /**
-     * Returns the age in years from the "current" date and 'now'
+     * Returns the age in years from the date and 'now'
      *
      * @throws Exception
      *
@@ -460,11 +460,12 @@ class Time extends DateTime
      */
     public function getAge()
     {
-        $now  = self::now()->getTimestamp();
-        $time = $this->getTimestamp();
+        $now = self::now();
+
+        $age = (int) (((int) $now->format('Ymd') - (int) $this->format('Ymd')) / 10000);
 
         // future dates have no age
-        return max(0, date('Y', $now) - date('Y', $time));
+        return max(0, $age);
     }
 
     /**
diff --git a/tests/system/I18n/TimeTest.php b/tests/system/I18n/TimeTest.php
index d7ffa72cd9..2db4fcc48c 100644
--- a/tests/system/I18n/TimeTest.php
+++ b/tests/system/I18n/TimeTest.php
@@ -402,6 +402,30 @@ final class TimeTest extends CIUnitTestCase
         $this->assertSame(0, $time->getAge());
     }
 
+    public function testGetAgeSameDayOfBirthday()
+    {
+        Time::setTestNow('December 31, 2022', 'America/Chicago');
+        $time = Time::parse('December 31, 2020');
+
+        $this->assertSame(2, $time->getAge());
+    }
+
+    public function testGetAgeNextDayOfBirthday()
+    {
+        Time::setTestNow('January 1, 2022', 'America/Chicago');
+        $time = Time::parse('December 31, 2020');
+
+        $this->assertSame(1, $time->getAge());
+    }
+
+    public function testGetAgeBeforeDayOfBirthday()
+    {
+        Time::setTestNow('December 30, 2021', 'America/Chicago');
+        $time = Time::parse('December 31, 2020');
+
+        $this->assertSame(0, $time->getAge());
+    }
+
     public function testGetQuarter()
     {
         $time = Time::parse('April 15, 2015');