Add JUnit tests for ItineraryTickets

Author: Imbiber

src/main/java/com/thealgorithms/datastructures/hashmap/hashing/ItineraryTickets.java

@@ -8,21 +8,6 @@
  */
 public class ItineraryTickets {
 
-    public static void main(String[] args) {
-        HashMap<String, String> tickets = new HashMap<>();
-        tickets.put("Chennai", "Bengaluru");
-        tickets.put("Mumbai", "Delhi");
-        tickets.put("Goa", "Chennai");
-        tickets.put("Delhi", "Goa");
-
-        String start = getStart(tickets);
-        System.out.print(start);
-        for (String key : tickets.keySet()) {
-            System.out.print(" -> " + tickets.get(start));
-            start = tickets.get(start);
-        }
-    }
-
     /**
      * This method finds the starting point of the itinerary.
      *

src/test/java/com/thealgorithms/datastructures/hashmap/hashing/ItineraryTicketsTest.java

@@ -0,0 +1,44 @@
+package com.thealgorithms.datastructures.hashmap.hashing;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class ItineraryTicketsTest {
+
+    private HashMap<String, String> tickets;
+
+    @BeforeEach
+    public void setUp() {
+        tickets = new HashMap<>();
+        tickets.put("Chennai", "Bengaluru");
+        tickets.put("Mumbai", "Delhi");
+        tickets.put("Goa", "Chennai");
+        tickets.put("Delhi", "Goa");
+    }
+
+    @Test
+    public void testGetStart() {
+        String start = ItineraryTickets.getStart(tickets);
+        assertEquals("Mumbai", start);
+    }
+
+    @Test
+    public void testGetStartEmptyInput() {
+        HashMap<String, String> emptyTickets = new HashMap<>();
+        String start = ItineraryTickets.getStart(emptyTickets);
+        assertNull(start);
+    }
+
+    @Test
+    public void testGetStartCircularItinerary() {
+        
+        tickets.put("Bengaluru", "Mumbai");
+        String start = ItineraryTickets.getStart(tickets);
+        assertNull(start); 
+    }
+}