diff --git a/projjpn/src/test/java/de/hs_fulda/ciip/projjpn/CustomersTest.java b/projjpn/src/test/java/de/hs_fulda/ciip/projjpn/CustomersTest.java
index e89d5e2..2816fc5 100644
--- a/projjpn/src/test/java/de/hs_fulda/ciip/projjpn/CustomersTest.java
+++ b/projjpn/src/test/java/de/hs_fulda/ciip/projjpn/CustomersTest.java
@@ -16,6 +16,22 @@ public class CustomersTest extends TestCase {
 		assertTrue(nicknameIsAvailable);
 	}
 	
+	public void test_nicknameIsTaken() {
+		// Given
+		Customers customers = new Customers();
+		String availableNickname = "beastMaster64";
+		String takenNickname = "beastMaster64";
+		User userToRegister = new User(availableNickname);
+		
+		customers.registerUser(userToRegister);
+		
+		// When
+		boolean nicknameIsTaken = !customers.nickNameAvailable(availableNickname);
+		
+		// Then
+		assertTrue(nicknameIsTaken);
+	}
+	
 	public void test_registerSingleUser() {
 		// Given
 		Customers customers = new Customers();