Added tests for DateTime __set_status

ext/date/tests/DateTime__set_state_basic.phpt

@@ -0,0 +1,23 @@
+--TEST--
+Basic test for __set_state() method
+--CREDITS--
+Gabriel da Gama <gabriel@gabrielgama.com.br>
+# PHPDublin PHPTestFest 2017
+--FILE--
+<?php
+date_default_timezone_set('Europe/Dublin');
+echo "*** Testing __set_state on DateTime objects ***\n";
+$dateTime = new DateTime('2017-10-18 19:50:00');
+eval('$b = ' . var_export($dateTime, true) . ';');
+var_dump($b);
+?>
+--EXPECTF--
+*** Testing __set_state on DateTime objects ***
+object(DateTime)#2 (3) {
+  ["date"]=>
+  string(26) "2017-10-18 19:50:00.000000"
+  ["timezone_type"]=>
+  int(3)
+  ["timezone"]=>
+  string(13) "Europe/Dublin"
+}

ext/date/tests/DateTime__set_state_error.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Test error on __set_state() method
+--CREDITS--
+Gabriel da Gama <gabriel@gabrielgama.com.br>
+# PHPDublin PHPTestFest 2017
+--FILE--
+<?php
+date_default_timezone_set('Europe/Dublin');
+echo "*** Testing error on __set_state on DateTime objects ***\n";
+var_dump(@DateTime::__set_state('error'));
+?>
+--EXPECTF--
+*** Testing error on __set_state on DateTime objects ***
+bool(false)