Add AgingScheduling algorithm (#5813)

src/test/java/com/thealgorithms/scheduling/AgingSchedulingTest.java

@@ -0,0 +1,54 @@
+package com.thealgorithms.scheduling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class AgingSchedulingTest {
+
+    private AgingScheduling scheduler;
+
+    @BeforeEach
+    public void setup() {
+        scheduler = new AgingScheduling();
+    }
+
+    @Test
+    public void testAddAndScheduleSingleTask() {
+        scheduler.addTask("Task1", 5);
+        assertEquals("Task1", scheduler.scheduleNext());
+    }
+
+    @Test
+    public void testAddMultipleTasks() {
+        scheduler.addTask("Task1", 1);
+        scheduler.addTask("Task2", 1);
+        assertEquals("Task1", scheduler.scheduleNext());
+        assertEquals("Task2", scheduler.scheduleNext());
+    }
+
+    @Test
+    public void testPriorityAdjustmentWithWait() {
+        scheduler.addTask("Task1", 1);
+        scheduler.addTask("Task2", 1);
+        scheduler.scheduleNext();
+        scheduler.scheduleNext();
+        assertEquals("Task1", scheduler.scheduleNext());
+    }
+
+    @Test
+    public void testEmptyScheduler() {
+        assertNull(scheduler.scheduleNext());
+    }
+
+    @Test
+    public void testMultipleRounds() {
+        scheduler.addTask("Task1", 1);
+        scheduler.addTask("Task2", 2);
+        scheduler.scheduleNext();
+        scheduler.scheduleNext();
+        assertEquals("Task1", scheduler.scheduleNext());
+    }
+}