make testing of inaccessible methods easier

While it's generally frowned upon testing privates, it can often be
useful and the easier way to write tests. Eg you want to test something
complicated method that is important, but you do not want to expose it
directly to other classes...

This new method uses reflection to make access to such methods possible
from within tests without the need for intermediate classes.

_test/core/DokuWikiTest.php

@@ -171,4 +171,24 @@ protected function waitForTick($init = false) {
         $last = $now;
         return $now;
     }
+
+    /**
+     * Allow for testing inaccessible methods (private or protected)
+     *
+     * This makes it easier to test protected methods without needing to create intermediate
+     * classes inheriting and changing the access.
+     *
+     * @link https://stackoverflow.com/a/8702347/172068
+     * @param object $obj Object in which to call the method
+     * @param string $func The method to call
+     * @param array $args The arguments to call the method with
+     * @return mixed
+     * @throws ReflectionException when the given obj/func does not exist
+     */
+    protected static function callInaccessibleMethod($obj, $func, array $args) {
+        $class = new \ReflectionClass($obj);
+        $method = $class->getMethod($func);
+        $method->setAccessible(true);
+        return $method->invokeArgs($obj, $args);
+    }
 }