Adding a new test for the new method

ext/date/tests/DateTime_createFromImmutable.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Tests for DateTime::createFromImmutable.
+--INI--
+date.timezone=America/New_York
+--FILE--
+<?php
+$current = "2015-03-05 07:00:16";
+
+$i = DateTime::createFromImmutable(date_create_immutable($current));
+var_dump($i);
+
+$i = DateTime::createFromImmutable(date_create($current));
+var_dump($i);
+?>
+--EXPECTF--
+object(DateTime)#%d (3) {
+  ["date"]=>
+  string(26) "2015-03-05 07:00:16.000000"
+  ["timezone_type"]=>
+  int(3)
+  ["timezone"]=>
+  string(13) "America/New_York"
+}
+
+Warning: DateTime::createFromImmutable() expects parameter 1 to be DateTimeImmutable, object given in %stests%eDateTime_createFromImmutable.php on line %d
+NULL