diff --git a/src/test/java/org/example/AdministrationTest.java b/src/test/java/org/example/AdministrationTest.java
index 4d2d885..647c024 100644
--- a/src/test/java/org/example/AdministrationTest.java
+++ b/src/test/java/org/example/AdministrationTest.java
@@ -324,4 +324,71 @@ class AdministrationTest {
 
     }
 
+    @Test
+    void registerUser() {
+        Administration administration = new Administration();
+        //Selects the userType
+        int userType = 1;
+
+        //Checks if the user Input correct; in this case its pre-determined
+        boolean correctData = false;
+        while(!correctData)
+        {
+            //User Input
+            String userName = "Tobias";
+            String userId = "S1010";
+
+            //Checks if the entered id is already being used
+            if(administration.findProfessorById(userId) != null || administration.findAdminById(userId) != null || administration.findStudentById(userId) != null) {
+
+            }
+            else if(administration.findProfessorById(userId) == null || administration.findAdminById(userId) == null || administration.findStudentById(userId) == null)
+            {
+                //the entered id is not used
+
+
+                if(!administration.rightPrefix(userId, userType))
+                {
+                    //the prefix is wrong
+
+                }
+                else if(!administration.isNumber(userId))
+                {
+                    //the substring does not contain only digits
+                    System.out.println("Every character besides the first one need to be digits");
+
+
+                }
+                else{
+                    //the id is not being used and has the right id-"syntax"
+                    System.out.println("The Id has not been used already!");
+                    correctData = true;
+                }
+
+            }
+
+            switch (userType)
+            {
+                case 1: //Student
+                    Student student = new Student(userName, userId, "Student");
+                    administration.addStudents(student);
+                    break;
+                case 2: //Admin
+                    Admin admin = new Admin(userName, userId, "Admin");
+                    administration.addAdmin(admin);
+                    break;
+                case 3: //Professor
+                    Professor professor = new Professor(userId, userName, "Professor");
+                    administration.addProfessor(professor);
+                default: //Error
+                    break;
+            }
+        }
+
+        //If All three are correct, the registerUser Function has been successful
+        assertEquals("Tobias", administration.findStudentById("S1010").getStudentName());
+        assertEquals("S1010", administration.findStudentById("S1010").getStudentId());
+        assertEquals("Student",administration.findStudentById("S1010").getStudentRole());
+
+    }
 }