Enhance docs, add tests in MinPriorityQueue (#5986)

src/test/java/com/thealgorithms/datastructures/heaps/MinPriorityQueueTest.java

@@ -0,0 +1,87 @@
+package com.thealgorithms.datastructures.heaps;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class MinPriorityQueueTest {
+
+    @Test
+    void testInsertAndPeek() {
+        MinPriorityQueue queue = new MinPriorityQueue(5);
+        queue.insert(10);
+        queue.insert(5);
+        queue.insert(15);
+
+        Assertions.assertEquals(5, queue.peek(), "The minimum element should be 5.");
+    }
+
+    @Test
+    void testDelete() {
+        MinPriorityQueue queue = new MinPriorityQueue(5);
+        queue.insert(10);
+        queue.insert(5);
+        queue.insert(15);
+
+        Assertions.assertEquals(5, queue.delete(), "The deleted minimum element should be 5.");
+        Assertions.assertEquals(10, queue.peek(), "After deletion, the new minimum should be 10.");
+    }
+
+    @Test
+    void testIsEmpty() {
+        MinPriorityQueue queue = new MinPriorityQueue(5);
+        Assertions.assertTrue(queue.isEmpty(), "The queue should be empty initially.");
+
+        queue.insert(10);
+        Assertions.assertFalse(queue.isEmpty(), "The queue should not be empty after insertion.");
+    }
+
+    @Test
+    void testIsFull() {
+        MinPriorityQueue queue = new MinPriorityQueue(2);
+        queue.insert(10);
+        queue.insert(5);
+
+        Assertions.assertTrue(queue.isFull(), "The queue should be full after inserting two elements.");
+        queue.delete();
+        Assertions.assertFalse(queue.isFull(), "The queue should not be full after deletion.");
+    }
+
+    @Test
+    void testHeapSort() {
+        MinPriorityQueue queue = new MinPriorityQueue(5);
+        queue.insert(10);
+        queue.insert(5);
+        queue.insert(15);
+        queue.insert(1);
+        queue.insert(3);
+
+        // Delete all elements to sort the queue
+        int[] sortedArray = new int[5];
+        for (int i = 0; i < 5; i++) {
+            sortedArray[i] = queue.delete();
+        }
+
+        Assertions.assertArrayEquals(new int[] {1, 3, 5, 10, 15}, sortedArray, "The array should be sorted in ascending order.");
+    }
+
+    @Test
+    void testPeekEmptyQueue() {
+        MinPriorityQueue queue = new MinPriorityQueue(5);
+        Assertions.assertThrows(IllegalStateException.class, queue::peek, "Should throw an exception when peeking into an empty queue.");
+    }
+
+    @Test
+    void testDeleteEmptyQueue() {
+        MinPriorityQueue queue = new MinPriorityQueue(5);
+        Assertions.assertThrows(IllegalStateException.class, queue::delete, "Should throw an exception when deleting from an empty queue.");
+    }
+
+    @Test
+    void testInsertWhenFull() {
+        MinPriorityQueue queue = new MinPriorityQueue(2);
+        queue.insert(10);
+        queue.insert(5);
+
+        Assertions.assertThrows(IllegalStateException.class, () -> queue.insert(15), "Should throw an exception when inserting into a full queue.");
+    }
+}