Implement ZonedDateTime::fromDateTime()

src/ZonedDateTime.php

@@ -217,6 +217,37 @@ public static function parse(string $text, DateTimeParser $parser = null) : Zone
 
         return ZonedDateTime::from($parser->parse($text));
     }
+    /**
+     * Creates a ZonedDateTime from a native DateTime object.
+     *
+     * @param \DateTimeInterface $dateTime
+     *
+     * @return ZonedDateTime
+     *
+     * @throws DateTimeException If the DateTime object has no timezone.
+     */
+    public static function fromDateTime(\DateTimeInterface $dateTime) : ZonedDateTime
+    {
+        $localDateTime = LocalDateTime::fromDateTime($dateTime);
+
+        $dateTimeZone = $dateTime->getTimezone();
+
+        if ($dateTimeZone === false) {
+            throw new DateTimeException('This DateTime object has no timezone.');
+        }
+
+        $timeZone = TimeZone::fromDateTimeZone($dateTimeZone);
+
+        if ($timeZone instanceof TimeZoneOffset) {
+            $timeZoneOffset = $timeZone;
+        } else {
+            $timeZoneOffset = TimeZoneOffset::ofTotalSeconds($dateTime->getOffset());
+        }
+
+        $instant = Instant::of($dateTime->getTimestamp(), $localDateTime->getNano());
+
+        return new ZonedDateTime($localDateTime, $timeZoneOffset, $timeZone, $instant);
+    }
 
     /**
      * Returns the `LocalDateTime` part of this `ZonedDateTime`.

tests/ZonedDateTimeTest.php

@@ -425,6 +425,31 @@ public function providerParseInvalidStringThrowsException() : array
         ];
     }
 
+    /**
+     * @dataProvider providerFromDateTime
+     *
+     * @param string $dateTimeString
+     * @param string $timeZone
+     * @param string $expected
+     */
+    public function testFromDateTime(string $dateTimeString, string $timeZone, string $expected)
+    {
+        $dateTime = new \DateTime($dateTimeString, new \DateTimeZone($timeZone));
+        $this->assertIs(ZonedDateTime::class, $expected, ZonedDateTime::fromDateTime($dateTime));
+    }
+
+    /**
+     * @return array
+     */
+    public function providerFromDateTime() : array
+    {
+        return [
+            ['2018-07-21 14:09:10.23456', 'America/Los_Angeles', '2018-07-21T14:09:10.23456-07:00[America/Los_Angeles]'],
+            ['2019-01-21 17:59', 'America/Los_Angeles', '2019-01-21T17:59-08:00[America/Los_Angeles]'],
+            ['2019-01-23 09:10:11.123', '+05:30', '2019-01-23T09:10:11.123+05:30'],
+        ];
+    }
+
     public function testChangeTimeZone()
     {
         $timezone1 = TimeZone::parse('UTC');