Add ZonedDateTime::getDurationTo method

src/ZonedDateTime.php

@@ -435,6 +435,15 @@ public function plusDuration(Duration $duration): ZonedDateTime
         return ZonedDateTime::ofInstant($this->instant->plus($duration), $this->timeZone);
     }
 
+    /**
+     * Returns a Duration representing the time elapsed between this ZonedDateTime and the given one.
+     * This method will return a negative duration if the given ZonedDateTime is before the current one.
+     */
+    public function getDurationTo(ZonedDateTime $that): Duration
+    {
+        return Duration::between($this->getInstant(), $that->getInstant());
+    }
+
     /**
      * Returns a copy of this ZonedDateTime with the specified period in years added.
      */

tests/ZonedDateTimeTest.php

@@ -834,6 +834,29 @@ public function testToString(): void
         $this->assertSame('2000-01-20T12:34:56.123456789-08:00[America/Los_Angeles]', (string) $zonedDateTime);
     }
 
+    /**
+     * @dataProvider providerGetDurationTo
+     */
+    public function testGetDurationTo(string $firstDate, string $secondDate, int $expectedSeconds, int $expectedNanos): void
+    {
+        $actualResult = ZonedDateTime::parse($firstDate)->getDurationTo(ZonedDateTime::parse($secondDate));
+
+        $this->assertDurationIs($expectedSeconds, $expectedNanos, $actualResult);
+    }
+
+    public function providerGetDurationTo(): array
+    {
+        return [
+            ['2023-01-01T10:00:00Z',           '2023-01-01T10:00:00Z',           0, 0],
+            ['2023-01-01T10:00:00Z',           '2023-01-01T10:00:10Z',           10, 0],
+            ['2023-01-01T10:00:00.001Z',       '2023-01-01T10:00:10.002Z',       10, 1000000],
+            ['2023-01-01T10:00:00.001Z',       '2023-01-01T13:00:10.002+03:00',  10, 1000000],
+            ['2023-01-01T10:00:00.000000001Z', '2023-01-01T10:00:00.000000009Z', 0, 8],
+            ['2023-01-01T10:00:00Z',           '2023-01-02T10:00:00Z',           24 * 60 * 60, 0],
+            ['2023-01-02T10:00:00Z',           '2023-01-01T10:00:00Z',           -24 * 60 * 60, 0],
+        ];
+    }
+
     private function getTestZonedDateTime(): ZonedDateTime
     {
         $timeZone = TimeZone::parse('America/Los_Angeles');