diff --git a/.idea/PHPUnitPlayground.iml b/.idea/PHPUnitPlayground.iml
index 3449561..a2c5002 100644
--- a/.idea/PHPUnitPlayground.iml
+++ b/.idea/PHPUnitPlayground.iml
@@ -40,12 +40,10 @@
     <orderEntry type="module-library">
       <library name="PHARS">
         <CLASSES>
-          <root url="phar://$MODULE_DIR$/composer.phar/" />
           <root url="phar://$MODULE_DIR$/vendor/phpunit/phpunit/tests/_files/phpunit-example-extension/tools/phpunit.d/phpunit-example-extension-1.0.1.phar/" />
           <root url="phar://$MODULE_DIR$/vendor/phar-io/manifest/tests/_fixture/test.phar/" />
         </CLASSES>
         <SOURCES>
-          <root url="phar://$MODULE_DIR$/composer.phar/" />
           <root url="phar://$MODULE_DIR$/vendor/phpunit/phpunit/tests/_files/phpunit-example-extension/tools/phpunit.d/phpunit-example-extension-1.0.1.phar/" />
           <root url="phar://$MODULE_DIR$/vendor/phar-io/manifest/tests/_fixture/test.phar/" />
         </SOURCES>
diff --git a/src/Sample4/AppController.php b/src/Sample4/AppController.php
new file mode 100644
index 0000000..e81329d
--- /dev/null
+++ b/src/Sample4/AppController.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Sample4;
+
+/**
+ * Class AppController
+ * Runs the application
+ * @package FrankFleige\PHPUnitPlayground\Sample4
+ */
+class AppController
+{
+
+    private $database;
+    private $config;
+    private $acrobat;
+
+    public function __construct()
+    {
+        $this->database = new Database();
+        $this->config = new ConfigurationRepository();
+        $this->acrobat = new StringAcrobat();
+    }
+
+    /**
+     * runs the app / runs the controller
+     */
+    public function run()
+    {
+        // take this model, all you need
+        $model = new Model(
+            $this->config->get("host"),
+            $this->config->get("port"),
+            $this->generateUniqueId());
+
+        echo $model->getShortURL();
+    }
+
+    /**
+     * Generates an unique id
+     * @return string
+     */
+    private function generateUniqueId()
+    {
+        $id = "";
+        do {
+            $id .= $this->acrobat->getRandomChar();
+        } while ($this->database->idExists($id));
+        return $id;
+    }
+}
\ No newline at end of file
diff --git a/src/Sample4/ConfigurationRepository.php b/src/Sample4/ConfigurationRepository.php
new file mode 100644
index 0000000..2db24b6
--- /dev/null
+++ b/src/Sample4/ConfigurationRepository.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Sample4;
+
+/**
+ * Class ConfigurationRepository
+ * This simple configuration repository represents a dependency.
+ * It's possible used by ALL controllers and models in the project
+ * In this example we try to give the needed configuration to the model.
+ * @package FrankFleige\PHPUnitPlayground\Sample4
+ */
+class ConfigurationRepository
+{
+    public function get(string $key)
+    {
+        switch ($key) {
+            case "host":
+                return "example.com";
+            case "port":
+                return "80";
+            default:
+                return null;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Sample4/Database.php b/src/Sample4/Database.php
new file mode 100644
index 0000000..26675ef
--- /dev/null
+++ b/src/Sample4/Database.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Sample4;
+
+/**
+ * Class Database
+ * This powerful database class can execute complex queries
+ * @package FrankFleige\PHPUnitPlayground\Sample4
+ */
+class Database
+{
+
+    /**
+     * We selecting the hole database and looking for the given id
+     * @param string $id
+     * @return bool
+     */
+    public function idExists(string $id)
+    {
+        if(strlen($id) <= 2) {
+            // all short ids are already assigned :-(
+            return true;
+        }
+
+        if(strlen($id) >= 12) {
+            // all long ids are unassigned ;-)
+            return false;
+        }
+
+        if(time()%2 === 0) {
+            // after a hard calculation within the database we are sure: this id already exists
+            return true;
+        }
+
+        // id was not found in the database
+        return false;
+    }
+
+}
\ No newline at end of file
diff --git a/src/Sample4/Model.php b/src/Sample4/Model.php
new file mode 100644
index 0000000..70460e3
--- /dev/null
+++ b/src/Sample4/Model.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Sample4;
+
+/**
+ * Class Model
+ * This model computes really hard stuff
+ * @package FrankFleige\PHPUnitPlayground\Sample4
+ */
+class Model
+{
+    private $protocol = "http";
+    private $host;
+    private $port;
+    private $id;
+
+    public function __construct(string $host, string $port, string $id)
+    {
+        $this->host = $host;
+        $this->port = $port;
+        $this->id = $id;
+    }
+
+    /**
+     * returns a short url
+     * @return string
+     */
+    public function getShortURL()
+    {
+        return "{$this->protocol}://{$this->host}:{$this->port}/{$this->id}";
+    }
+
+
+
+}
\ No newline at end of file
diff --git a/src/Sample4/StringAcrobat.php b/src/Sample4/StringAcrobat.php
new file mode 100644
index 0000000..70cf93c
--- /dev/null
+++ b/src/Sample4/StringAcrobat.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Sample4;
+
+/**
+ * Class StringAcrobat
+ * The string acrobat is a helper class (model)
+ * @package FrankFleige\PHPUnitPlayground\Sample4
+ */
+class StringAcrobat
+{
+    /**
+     * Returns a random char
+     * @return string
+     */
+    public function getRandomChar()
+    {
+        $alphabet = array_merge(range("0","9"), range("a", "z"), range("A", "Z"));
+        shuffle($alphabet);
+        return $alphabet[0];
+    }
+}
\ No newline at end of file
diff --git a/src/Sample4/index.php b/src/Sample4/index.php
new file mode 100644
index 0000000..397fb06
--- /dev/null
+++ b/src/Sample4/index.php
@@ -0,0 +1,6 @@
+<?php
+
+require dirname(dirname(__DIR__)) . DIRECTORY_SEPARATOR . "vendor" . DIRECTORY_SEPARATOR . "autoload.php";
+
+$app = new \FrankFleige\PHPUnitPlayground\Sample4\AppController();
+$app->run();
\ No newline at end of file
diff --git a/test/TestSample4/ModelTest.php b/test/TestSample4/ModelTest.php
new file mode 100644
index 0000000..9bb11a7
--- /dev/null
+++ b/test/TestSample4/ModelTest.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Test\TestSample4;
+
+use FrankFleige\PHPUnitPlayground\Sample4\Model;
+use PHPUnit\Framework\TestCase;
+
+class ModelTest extends TestCase
+{
+    public function testGetShortUrl()
+    {
+        $m = new Model("test.de", "8080", "1234567890");
+        $this->assertEquals("http://test.de:8080/1234567890", $m->getShortURL());
+    }
+}
diff --git a/test/TestSample4/StringAcrobatTest.php b/test/TestSample4/StringAcrobatTest.php
new file mode 100644
index 0000000..7a173dc
--- /dev/null
+++ b/test/TestSample4/StringAcrobatTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace FrankFleige\PHPUnitPlayground\Test\TestSample4;
+
+use FrankFleige\PHPUnitPlayground\Sample4\StringAcrobat;
+use PHPUnit\Framework\TestCase;
+
+class StringAcrobatTest extends TestCase
+{
+
+    public function testGetRandomChar()
+    {
+        $sa = new StringAcrobat();
+        $this->assertEquals(1, strlen($sa->getRandomChar()));
+        $this->assertTrue(is_string($sa->getRandomChar()));
+        $alphabetCorrect = range("!", "z");
+        $this->assertTrue(in_array($sa->getRandomChar(), $alphabetCorrect));
+        $alphabetWrong = ["ä", "ö", "ü", "ß", "Ä", "Ü", "Ö"];
+        $this->assertFalse(in_array($sa->getRandomChar(), $alphabetWrong));
+    }
+}