Added back function to MenuManager.

src/main/java/Application/MenuManager.java

@@ -14,6 +14,13 @@ public class MenuManager {
         this.currentMenu = currentMenu.getMenu(i);
     }
 
+    public void back() throws Exception {
+        if(!this.inRootMenu())
+            this.currentMenu = this.currentMenu.getPreviousMenu();
+        else
+            throw new Exception("Menu is a root menu, a previous menu doesn't exist");
+    }
+
     public Menu getCurrentMenu(){
         return this.currentMenu;
     }

src/test/java/Application/MenuManagerTest.java

@@ -1,6 +1,7 @@
 package Application;
 
 import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -42,4 +43,29 @@ class MenuManagerTest {
         mm.select(0);
         assertFalse(mm.inRootMenu());
     }
+
+    @Test
+    void testBackFunction() {
+        try {
+            mm.back();
+            Assertions.fail("Test failed: shouldn't be able to go back in rootMenu");
+        } catch (Exception e) {
+            //Should throw Exception because currently in rootMenu
+        }
+        mm.select(0);
+        try {
+            mm.back();
+            assertEquals(mm.getCurrentMenu(), rootMenu);
+        } catch (Exception e) {
+            Assertions.fail("Test failed: " + e.getMessage());
+        }
+        mm.select(0);
+        mm.select(0);
+        try {
+            mm.back();
+            assertEquals(mm.getCurrentMenu(), rootMenu.getMenu(0));
+        } catch (Exception e) {
+            Assertions.fail("Test failed: " + e.getMessage());
+        }
+    }
 }