Added testing for the friend list and equals in User class in Server

src/Server/src/main/java/greenify/server/data/model/User.java

@@ -1,5 +1,7 @@
 package greenify.server.data.model;
 
+import greenify.common.ApplicationException;
+import greenify.server.Application;
 import lombok.Data;
 
 import java.util.ArrayList;
@@ -101,8 +103,13 @@ public class User {
     }
 
     public void addFriend(User user){
+        if(!user.equals(this)) {
             friends.add(user);
         }
+        else {
+            throw new ApplicationException("Cannnot add yourself as a friend");
+        }
+    }
 
     /**
      * Returns a human readable object. It's in JSON.

src/Server/src/test/java/greenify/server/data/model/UserTest.java

@@ -1,11 +1,18 @@
 package greenify.server.data.model;
 
+import static greenify.server.data.model.User.*;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import greenify.common.ApplicationException;
+import greenify.server.Application;
 import org.junit.Test;
 
+import java.util.ArrayList;
+
 public class UserTest {
     @Test
     public void setAndGetTest() {
@@ -28,6 +35,13 @@ public class UserTest {
         assertEquals("User(id=1, name=greenify, password=password, veganMeal=3)", user.toString());
     }
 
+    @Test
+    public void equalsNullTest(){
+        User first = new User(1L, "greenify", "password", 0);
+        User second = null;
+        assertNotEquals(first, second);
+    }
+
     @Test
     public void equalsTest() {
         User first = new User(1L, "greenify", "password", 3);
@@ -46,6 +60,12 @@ public class UserTest {
         assertFalse(first.equals(second));
     }
 
+    @Test
+    public void sameEqualsTest(){
+        User user = new User(6l, "Merel", "password", 0);
+        assertEquals(user, user);
+    }
+
     @Test
     public void instanceOfTest() {
         User first = new User();
@@ -60,5 +80,25 @@ public class UserTest {
         assertEquals(first, second);
         assertEquals(first.hashCode(), second.hashCode());
     }
+
+    @Test
+    public void addFriendTest(){
+        User user = new User(1l, "user", "friends", 0);
+        User friend = new User(2l, "friend", "friends", 0);
+        assertEquals(user.getFriends(), new ArrayList<User>());
+        user.addFriend(friend);
+        ArrayList<User> list = new ArrayList<User>();
+        list.add(friend);
+        assertEquals(user.getFriends(), list);
+    }
+
+    @Test
+    public void addYourselfTest(){
+        User user = new User(1l, "user", "friends", 0);
+        assertThrows(ApplicationException.class, () -> {
+            user.addFriend(user);
+        });
+        assertEquals(user.getFriends(), new ArrayList<User>());
+    }
 }