Make LinkedQueue generic (#3909)

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

@@ -0,0 +1,29 @@
+package com.thealgorithms.datastructures.queues;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+
+class LinkedQueueTest {
+  @Test
+  public void testQue() {
+    LinkedQueue<Integer> queue = new LinkedQueue<>();
+    for (int i = 1; i < 5; i++)
+      queue.enqueue(i);
+
+    assertEquals(queue.peekRear(), 4);
+    assertEquals(queue.peek(2), 2);
+
+    assertEquals(queue.peek(4), 4);
+
+    final int[] element = { 1 };
+
+    // iterates over all the elements present
+    // as in the form of nodes
+    queue.forEach(integer -> {
+      if (element[0]++ != integer)
+        throw new AssertionError();
+    });
+  }
+}