Add GangScheduling algorithm (#5819)

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

@@ -0,0 +1,52 @@
+package com.thealgorithms.scheduling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+import java.util.Map;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class GangSchedulingTest {
+
+    private GangScheduling scheduler;
+
+    @BeforeEach
+    public void setup() {
+        scheduler = new GangScheduling();
+    }
+
+    @Test
+    public void testAddGangAndTask() {
+        scheduler.addGang("Gang1");
+        scheduler.addTaskToGang("Gang1", "Task1");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of("Task1"));
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+
+    @Test
+    public void testMultipleGangs() {
+        scheduler.addGang("Gang1");
+        scheduler.addGang("Gang2");
+        scheduler.addTaskToGang("Gang1", "Task1");
+        scheduler.addTaskToGang("Gang2", "Task2");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of("Task1"), "Gang2", List.of("Task2"));
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+
+    @Test
+    public void testGangWithMultipleTasks() {
+        scheduler.addGang("Gang1");
+        scheduler.addTaskToGang("Gang1", "Task1");
+        scheduler.addTaskToGang("Gang1", "Task2");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of("Task1", "Task2"));
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+
+    @Test
+    public void testEmptyGangSchedule() {
+        scheduler.addGang("Gang1");
+        Map<String, List<String>> expected = Map.of("Gang1", List.of());
+        assertEquals(expected, scheduler.getGangSchedules());
+    }
+}