Java/src/test/java/com/examplehub/basics/queue/QueueExampleTest.java at list · letscode-17/Java · GitHub

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package com.examplehub.basics.queue;

import static org.junit.jupiter.api.Assertions.*;

import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Queue;
import org.junit.jupiter.api.Test;

class QueueExampleTest {
  @Test
  void testAdd() {
    Queue<String> queue = new LinkedList<>();
    queue.add("A");
    assertEquals("[A]", queue.toString());
  }

  @Test
  void testOffer() {
    Queue<String> queue = new LinkedList<>();
    assertTrue(queue.offer("A"));
    assertEquals("[A]", queue.toString());
  }

  @Test
  void testSize() {
    Queue<String> queue = new LinkedList<>();
    assertTrue(queue.offer("A"));
    assertEquals(1, queue.size());
  }

  @Test
  void testRemove() {
    Queue<String> queue = new LinkedList<>();
    assertTrue(queue.offer("A"));
    assertTrue(queue.offer("B"));
    assertTrue(queue.offer("C"));
    assertTrue(queue.offer("D"));

    assertEquals("A", queue.remove());
    assertEquals("B", queue.remove());
    assertEquals("C", queue.remove());
    assertEquals("D", queue.remove());

    assertEquals(0, queue.size());
    try {
      queue.remove();
      fail();
    } catch (NoSuchElementException e) {
      assertTrue(true);
    }
  }

  @Test
  void testPool() {
    Queue<String> queue = new LinkedList<>();
    assertTrue(queue.offer("A"));
    assertTrue(queue.offer("B"));
    assertTrue(queue.offer("C"));
    assertTrue(queue.offer("D"));

    assertEquals("A", queue.poll());
    assertEquals("B", queue.poll());
    assertEquals("C", queue.poll());
    assertEquals("D", queue.poll());

    assertEquals(0, queue.size());

    assertNull(queue.poll());
  }

  @Test
  void testPeek() {
    Queue<String> queue = new LinkedList<>();
    assertTrue(queue.offer("A"));
    assertTrue(queue.offer("B"));
    assertTrue(queue.offer("C"));
    assertTrue(queue.offer("D"));

    assertEquals("A", queue.peek());
    assertEquals("A", queue.peek());
  }

  @Test
  void testElement() {
    Queue<String> queue = new LinkedList<>();
    assertTrue(queue.offer("A"));
    assertTrue(queue.offer("B"));
    assertTrue(queue.offer("C"));
    assertTrue(queue.offer("D"));

    assertEquals("A", queue.element());
    assertEquals("A", queue.element());
  }
}