Added some unit tests.

tests/RelativeDateType3Test.php

@@ -0,0 +1,19 @@
+<?php
+
+use enko\RelativeDateParser\RelativeDateParser;
+
+class RelativeDateType3Test extends PHPUnit_Framework_TestCase
+{
+    public function testNextDate()
+    {
+        $now = new DateTime('2014-07-07');
+        $next_date = new DateTime('2014-08-05');
+
+        /** @var RelativeDateParser $parser */
+        $parser = new RelativeDateParser('Jeder 5. Tag eines Monats', $now, 'de');
+
+
+        // Assert
+        $this->assertEquals($next_date->format('c'), $parser->getNext()->format('c'));
+    }
+}