feat: Add RandomScheduling new algorithm with Junit tests

Author: Hardvan

src/main/java/com/thealgorithms/scheduling/RandomScheduling.java

@@ -0,0 +1,44 @@
+package com.thealgorithms.scheduling;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Random;
+
+/**
+ * RandomScheduling is an algorithm that assigns tasks in a random order.
+ * It doesn't consider priority, deadlines, or burst times, making it
+ * inefficient but useful in scenarios where fairness or unpredictability
+ * is required (e.g., load balancing in distributed systems).
+ *
+ * Use Case: Distributed systems where randomness helps avoid task starvation.
+ *
+ * @author Hardvan
+ */
+public final class RandomScheduling {
+
+    private final List<String> tasks;
+    private final Random random;
+
+    /**
+     * Constructs a new RandomScheduling instance.
+     *
+     * @param tasks A list of task names to be scheduled.
+     * @param random A Random instance for generating random numbers.
+     */
+    public RandomScheduling(List<String> tasks, Random random) {
+        this.tasks = new ArrayList<>(tasks); // Store tasks locally
+        this.random = random;
+    }
+
+    /**
+     * Schedules the tasks randomly and returns the randomized order.
+     *
+     * @return A list representing the tasks in their randomized execution order.
+     */
+    public List<String> schedule() {
+        List<String> shuffledTasks = new ArrayList<>(tasks);
+        Collections.shuffle(shuffledTasks, random);
+        return shuffledTasks;
+    }
+}

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

@@ -0,0 +1,91 @@
+package com.thealgorithms.scheduling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.*;
+
+import java.util.List;
+import java.util.Random;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class RandomSchedulingTest {
+
+    private RandomScheduling randomScheduling;
+    private Random mockRandom;
+
+    @BeforeEach
+    public void setup() {
+        mockRandom = mock(Random.class); // Mocking Random for predictable behavior
+    }
+
+    @Test
+    public void testRandomOrder1() {
+        // Arrange
+        List<String> tasks = List.of("Task1", "Task2", "Task3");
+        // Mock the random sequence to control shuffling: swap 0 <-> 1, and 1 <-> 2.
+        when(mockRandom.nextInt(anyInt())).thenReturn(1, 2, 0);
+        randomScheduling = new RandomScheduling(tasks, mockRandom);
+
+        // Act
+        List<String> result = randomScheduling.schedule();
+
+        // Assert
+        assertEquals(List.of("Task1", "Task2", "Task3"), result);
+    }
+
+    @Test
+    public void testRandomOrder2() {
+        // Arrange
+        List<String> tasks = List.of("A", "B", "C", "D");
+        // Mocking predictable swaps for the sequence: [C, B, D, A]
+        when(mockRandom.nextInt(anyInt())).thenReturn(2, 1, 3, 0);
+        randomScheduling = new RandomScheduling(tasks, mockRandom);
+
+        // Act
+        List<String> result = randomScheduling.schedule();
+
+        // Assert
+        assertEquals(List.of("A", "C", "B", "D"), result);
+    }
+
+    @Test
+    public void testSingleTask() {
+        // Arrange
+        List<String> tasks = List.of("SingleTask");
+        when(mockRandom.nextInt(anyInt())).thenReturn(0); // No real shuffle
+        randomScheduling = new RandomScheduling(tasks, mockRandom);
+
+        // Act
+        List<String> result = randomScheduling.schedule();
+
+        // Assert
+        assertEquals(List.of("SingleTask"), result);
+    }
+
+    @Test
+    public void testEmptyTaskList() {
+        // Arrange
+        List<String> tasks = List.of();
+        randomScheduling = new RandomScheduling(tasks, mockRandom);
+
+        // Act
+        List<String> result = randomScheduling.schedule();
+
+        // Assert
+        assertEquals(List.of(), result); // Should return an empty list
+    }
+
+    @Test
+    public void testSameTasksMultipleTimes() {
+        // Arrange
+        List<String> tasks = List.of("X", "X", "Y", "Z");
+        when(mockRandom.nextInt(anyInt())).thenReturn(3, 0, 1, 2);
+        randomScheduling = new RandomScheduling(tasks, mockRandom);
+
+        // Act
+        List<String> result = randomScheduling.schedule();
+
+        // Assert
+        assertEquals(List.of("Y", "X", "X", "Z"), result);
+    }
+}