Return ChronosInterval from Chronos::diff()

phpstan.neon

@@ -17,3 +17,6 @@ parameters:
 			message: "#with generic class DatePeriod but does not specify its types: TDate, TEnd, TRecurrences$#"
 			count: 1
 			path: src/ChronosDatePeriod.php
+		-
+			identifier: method.childReturnType
+			path: src/Chronos.php

src/Chronos.php

@@ -20,6 +20,7 @@
 use DateTimeInterface;
 use DateTimeZone;
 use InvalidArgumentException;
+use ReturnTypeWillChange;
 use RuntimeException;
 use Stringable;
 
@@ -1011,11 +1012,12 @@ public function modify(string $modifier): static
      *
      * @param \DateTimeInterface $target Target instance
      * @param bool $absolute Whether the interval is forced to be positive
-     * @return \DateInterval
+     * @return \Cake\Chronos\ChronosInterval
      */
-    public function diff(DateTimeInterface $target, bool $absolute = false): DateInterval
+    #[ReturnTypeWillChange]
+    public function diff(DateTimeInterface $target, bool $absolute = false): ChronosInterval
     {
-        return parent::diff($target, $absolute);
+        return new ChronosInterval(parent::diff($target, $absolute));
     }
 
     /**
@@ -2778,9 +2780,9 @@ public function secondsUntilEndOfDay(): int
      * Convenience method for getting the remaining time from a given time.
      *
      * @param \DateTimeInterface $other The date to get the remaining time from.
-     * @return \DateInterval|bool The DateInterval object representing the difference between the two dates or FALSE on failure.
+     * @return \Cake\Chronos\ChronosInterval The ChronosInterval object representing the difference between the two dates.
      */
-    public static function fromNow(DateTimeInterface $other): DateInterval|bool
+    public static function fromNow(DateTimeInterface $other): ChronosInterval
     {
         $timeNow = new static();
 

src/ChronosDate.php

@@ -407,11 +407,11 @@ public function setISODate(int $year, int $week, int $dayOfWeek = 1): static
      *
      * @param \Cake\Chronos\ChronosDate $target Target instance
      * @param bool $absolute Whether the interval is forced to be positive
-     * @return \DateInterval
+     * @return \Cake\Chronos\ChronosInterval
      */
-    public function diff(ChronosDate $target, bool $absolute = false): DateInterval
+    public function diff(ChronosDate $target, bool $absolute = false): ChronosInterval
     {
-        return $this->native->diff($target->native, $absolute);
+        return new ChronosInterval($this->native->diff($target->native, $absolute));
     }
 
     /**

tests/TestCase/ChronosIntervalTest.php

@@ -15,11 +15,32 @@
 namespace Cake\Chronos\Test\TestCase;
 
 use Cake\Chronos\Chronos;
+use Cake\Chronos\ChronosDate;
 use Cake\Chronos\ChronosInterval;
 use DateInterval;
 
 class ChronosIntervalTest extends TestCase
 {
+    public function testChronosDiffReturnsChronosInterval(): void
+    {
+        $start = new Chronos('2020-01-01');
+        $end = new Chronos('2020-01-11');
+        $diff = $start->diff($end);
+
+        $this->assertInstanceOf(ChronosInterval::class, $diff);
+        $this->assertSame(10, $diff->d);
+    }
+
+    public function testChronosDateDiffReturnsChronosInterval(): void
+    {
+        $start = ChronosDate::create(2020, 1, 1);
+        $end = ChronosDate::create(2020, 1, 11);
+        $diff = $start->diff($end);
+
+        $this->assertInstanceOf(ChronosInterval::class, $diff);
+        $this->assertSame(10, $diff->d);
+    }
+
     public function testCreateFromSpec(): void
     {
         $interval = ChronosInterval::create('P1Y2M3D');
@@ -88,10 +109,8 @@ public function testToIso8601StringNegative(): void
     {
         $past = new Chronos('2020-01-01');
         $future = new Chronos('2021-02-02');
-        $diff = $past->diff($future);
-        $diff->invert = 1;
+        $interval = $future->diff($past);
 
-        $interval = ChronosInterval::instance($diff);
         $this->assertStringStartsWith('-P', $interval->toIso8601String());
     }
 
@@ -123,9 +142,8 @@ public function testTotalDaysFromDiff(): void
     {
         $start = new Chronos('2020-01-01');
         $end = new Chronos('2020-01-11');
-        $diff = $start->diff($end);
+        $interval = $start->diff($end);
 
-        $interval = ChronosInterval::instance($diff);
         $this->assertSame(10, $interval->totalDays());
     }
 
@@ -136,9 +154,8 @@ public function testIsNegative(): void
 
         $past = new Chronos('2020-01-01');
         $future = new Chronos('2020-01-02');
-        $diff = $future->diff($past);
+        $interval = $future->diff($past);
 
-        $interval = ChronosInterval::instance($diff);
         $this->assertTrue($interval->isNegative());
     }
 
@@ -296,9 +313,8 @@ public function testToDateStringNegative(): void
     {
         $past = new Chronos('2020-01-01');
         $future = new Chronos('2020-01-02');
-        $diff = $future->diff($past);
+        $interval = $future->diff($past);
 
-        $interval = ChronosInterval::instance($diff);
         $this->assertStringStartsWith('-', $interval->toDateString());
     }