keep DateTimeImmutable inner and outer dates in sync, fixes #759

lib/DateTimeImmutable.php

@@ -24,8 +24,8 @@ class DateTimeImmutable extends \DateTimeImmutable
      */
     public function __construct($time = 'now', $timezone = null)
     {
-        parent::__construct($time, $timezone);
         $this->innerDateTime = new parent($time, $timezone);
+        parent::__construct($this->innerDateTime->format('Y-m-d H:i:s.u'), $this->innerDateTime->getTimezone());
     }
 
     //switch between regular datetime and safe version

tests/DateTimeImmutableTest.php

@@ -45,7 +45,7 @@
     public function testCreateFromFormatCrashOnError(): void
     {
         $this->expectException(\Safe\Exceptions\DatetimeException::class);
         $datetime = \Safe\DateTimeImmutable::createFromFormat('lol', 'super');
     }
 
     public function testConstructorPreserveTimeAndTimezone(): void
@@ -56,6 +56,31 @@
         $this->assertEquals($timezone, $datetime->getTimezone());
     }
 
+    public function testConstructorInnerAndOuterDatesAreEqual(): void
+    {
+        for ($i = 0; $i < 1000; $i++) {
+            $datetime = new \Safe\DateTimeImmutable();
+            $this->assertSame(
+                self::nativeFormat($datetime, 'Y-m-d H:i:s.u'),
+                $datetime->getInnerDateTime()->format('Y-m-d H:i:s.u')
+            );
+        }
+    }
+
+    public function testConstructorPreservesTimezoneFromTimeString(): void
+    {
+        foreach (['@1700000000', '2020-01-01T00:00:00+02:00'] as $time) {
+            $datetime = new \Safe\DateTimeImmutable($time);
+            $this->assertSame(self::nativeFormat($datetime, 'U P'), $datetime->getInnerDateTime()->format('U P'));
+        }
+    }
+
+    private static function nativeFormat(\DateTimeImmutable $datetime, string $format): string
+    {
+        // bypass \Safe\DateTimeImmutable::format() to read the parent's own value
+        return (new \ReflectionMethod(\DateTimeImmutable::class, 'format'))->invoke($datetime, $format);
+    }
+
     public function testCreateFromFormatPreserveTimeAndTimezone(): void
     {
         $timezone = new \DateTimeZone('Pacific/Chatham');
@@ -109,7 +134,7 @@
     {
         $datetime = new \DateTimeImmutable('2000-01-01');
         $safeDatime = new \Safe\DateTimeImmutable('2000-01-01');
         $datetime = $datetime = $datetime->setTimestamp(12);
         $safeDatime = $safeDatime->setTimestamp(12);
 
         $this->assertEquals($datetime->getTimestamp(), $safeDatime->getTimestamp());