refactor: Queue (#5348)

src/test/java/com/thealgorithms/datastructures/queues/QueueTest.java

@@ -0,0 +1,127 @@
+package com.thealgorithms.datastructures.queues;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class QueueTest {
+
+    private static final int INITIAL_CAPACITY = 3;
+    private Queue<Integer> queue;
+
+    @BeforeEach
+    void setUp() {
+        queue = new Queue<>(INITIAL_CAPACITY);
+    }
+
+    @Test
+    void testQueueInsertion() {
+        Assertions.assertTrue(queue.insert(1));
+        Assertions.assertTrue(queue.insert(2));
+        Assertions.assertTrue(queue.insert(3));
+        Assertions.assertFalse(queue.insert(4)); // Queue is full
+
+        Assertions.assertEquals(1, queue.peekFront());
+        Assertions.assertEquals(3, queue.peekRear());
+        Assertions.assertEquals(3, queue.getSize());
+    }
+
+    @Test
+    void testQueueRemoval() {
+        queue.insert(1);
+        queue.insert(2);
+        queue.insert(3);
+
+        Assertions.assertEquals(1, queue.remove());
+        Assertions.assertEquals(2, queue.peekFront());
+        Assertions.assertEquals(2, queue.getSize());
+
+        Assertions.assertEquals(2, queue.remove());
+        Assertions.assertEquals(3, queue.peekFront());
+        Assertions.assertEquals(1, queue.getSize());
+
+        Assertions.assertEquals(3, queue.remove());
+        Assertions.assertTrue(queue.isEmpty());
+
+        Assertions.assertThrows(IllegalStateException.class, queue::remove); // Queue is empty
+    }
+
+    @Test
+    void testPeekFrontAndRear() {
+        queue.insert(1);
+        queue.insert(2);
+
+        Assertions.assertEquals(1, queue.peekFront());
+        Assertions.assertEquals(2, queue.peekRear());
+
+        queue.insert(3);
+        Assertions.assertEquals(1, queue.peekFront());
+        Assertions.assertEquals(3, queue.peekRear());
+    }
+
+    @Test
+    void testQueueIsEmptyAndIsFull() {
+        Assertions.assertTrue(queue.isEmpty());
+        Assertions.assertFalse(queue.isFull());
+
+        queue.insert(1);
+        queue.insert(2);
+        queue.insert(3);
+
+        Assertions.assertFalse(queue.isEmpty());
+        Assertions.assertTrue(queue.isFull());
+
+        queue.remove();
+        Assertions.assertFalse(queue.isFull());
+        Assertions.assertFalse(queue.isEmpty());
+    }
+
+    @Test
+    void testQueueSize() {
+        Assertions.assertEquals(0, queue.getSize());
+        queue.insert(1);
+        Assertions.assertEquals(1, queue.getSize());
+        queue.insert(2);
+        Assertions.assertEquals(2, queue.getSize());
+        queue.insert(3);
+        Assertions.assertEquals(3, queue.getSize());
+        queue.remove();
+        Assertions.assertEquals(2, queue.getSize());
+    }
+
+    @Test
+    void testQueueToString() {
+        Assertions.assertEquals("[]", queue.toString());
+
+        queue.insert(1);
+        queue.insert(2);
+        Assertions.assertEquals("[1, 2]", queue.toString());
+
+        queue.insert(3);
+        Assertions.assertEquals("[1, 2, 3]", queue.toString());
+
+        queue.remove();
+        Assertions.assertEquals("[2, 3]", queue.toString());
+
+        queue.remove();
+        queue.remove();
+        Assertions.assertEquals("[]", queue.toString());
+    }
+
+    @Test
+    void testQueueThrowsExceptionOnEmptyPeek() {
+        Assertions.assertThrows(IllegalStateException.class, queue::peekFront);
+        Assertions.assertThrows(IllegalStateException.class, queue::peekRear);
+    }
+
+    @Test
+    void testQueueThrowsExceptionOnRemoveFromEmptyQueue() {
+        Assertions.assertThrows(IllegalStateException.class, queue::remove);
+    }
+
+    @Test
+    void testQueueCapacityException() {
+        Assertions.assertThrows(IllegalArgumentException.class, () -> new Queue<>(0));
+        Assertions.assertThrows(IllegalArgumentException.class, () -> new Queue<>(-5));
+    }
+}