diff --git a/src/main/java/io/fp/campus/Faculty.java b/src/main/java/io/fp/campus/Faculty.java
index feb969c2ba5cc46c4c29d67f5f634e7842e19f9f..a7436b088c7b8bb8b640296d74d2774334cab8a6 100644
--- a/src/main/java/io/fp/campus/Faculty.java
+++ b/src/main/java/io/fp/campus/Faculty.java
@@ -21,8 +21,12 @@ public class Faculty {
     }
 
     public void addProfessor(Professor professor) {
-        if (!profs.contains(professor))
+        if (!profs.contains(professor)) {
             profs.add(professor);
+        }
+        else {
+            throw new RuntimeException();
+        }
     }
 
     public void addAssistent(Assistent assistent) {
diff --git a/src/test/java/io/fp/campus/FacultyTest.java b/src/test/java/io/fp/campus/FacultyTest.java
index c0c664974d34ec7710a72413adcb80f85a4b6f86..1abc6591b516483b2188200855702b32b67e6b76 100644
--- a/src/test/java/io/fp/campus/FacultyTest.java
+++ b/src/test/java/io/fp/campus/FacultyTest.java
@@ -1,10 +1,11 @@
 package io.fp.campus;
 
 import java.util.ArrayList;
-
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 public class FacultyTest {
 
@@ -13,21 +14,16 @@ public class FacultyTest {
     @BeforeEach
     void setUp() {
         hogwarts = new Faculty("Hogwarts");
-        Professor dumbledore = new Professor("Dumbledore", 77, "BPM", hogwarts);
-        dumbledore.setTalking(false);
-        
+        Professor dumbledore = new Professor("Dumbledore", 77, "Dragons", hogwarts);
+                
         Assistent hagrid = new Assistent("Hagrid", 26, hogwarts);
         hagrid.setBoss(dumbledore);
-
         Assistent dobby = new Assistent("Dobby", 130, hogwarts);
         dobby.setBoss(dumbledore);
-
-        Assistent pince = new Assistent("Madam Pince", 40, hogwarts);
-        
+       
         hogwarts.addProfessor(dumbledore);
         hogwarts.addAssistent(hagrid);
         hogwarts.addAssistent(dobby);
-        hogwarts.addAssistent(pince);
     }
     @Test
     void testGetProfsWithAssis() {
@@ -35,4 +31,13 @@ public class FacultyTest {
         ArrayList<Professor> profsWithAssis = hogwarts.getProfsWithAssis();
         assertEquals(profs, profsWithAssis);
     }
+
+    @Test
+    void testAddProfessor() {
+      ArrayList<Professor> profs = hogwarts.getProfs();
+      Professor prof1 = profs.get(0);
+      assertThrows(RuntimeException.class,
+          ()->{hogwarts.addProfessor(prof1);}
+      );  
+    }
 }
\ No newline at end of file