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refactor: LinkedQueue (#5352)
This commit is contained in:
Alex Klymenko
@ -1,30 +1,209 @@
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package com.thealgorithms.datastructures.queues;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import static org.junit.jupiter.api.Assertions.assertFalse;
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import static org.junit.jupiter.api.Assertions.assertTrue;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import org.junit.jupiter.api.BeforeEach;
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import org.junit.jupiter.api.Test;
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class LinkedQueueTest {
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private LinkedQueue<Integer> queue;
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@BeforeEach
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void setUp() {
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queue = new LinkedQueue<>();
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}
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@Test
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public void testQue() {
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LinkedQueue<Integer> queue = new LinkedQueue<>();
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for (int i = 1; i < 5; i++) {
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void testIsEmptyOnNewQueue() {
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assertTrue(queue.isEmpty(), "Queue should be empty on initialization.");
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}
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@Test
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void testEnqueueAndSize() {
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queue.enqueue(10);
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assertFalse(queue.isEmpty(), "Queue should not be empty after enqueue.");
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assertEquals(1, queue.size(), "Queue size should be 1 after one enqueue.");
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals(3, queue.size(), "Queue size should be 3 after three enqueues.");
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}
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@Test
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void testDequeueOnSingleElementQueue() {
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queue.enqueue(10);
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assertEquals(10, queue.dequeue(), "Dequeued element should be the same as the enqueued one.");
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assertTrue(queue.isEmpty(), "Queue should be empty after dequeueing the only element.");
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}
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@Test
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void testDequeueMultipleElements() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals(10, queue.dequeue(), "First dequeued element should be the first enqueued one.");
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assertEquals(20, queue.dequeue(), "Second dequeued element should be the second enqueued one.");
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assertEquals(30, queue.dequeue(), "Third dequeued element should be the third enqueued one.");
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assertTrue(queue.isEmpty(), "Queue should be empty after dequeueing all elements.");
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}
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@Test
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void testDequeueOnEmptyQueue() {
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org.junit.jupiter.api.Assertions.assertThrows(NoSuchElementException.class, () -> queue.dequeue(), "Dequeueing from an empty queue should throw NoSuchElementException.");
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}
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@Test
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void testPeekFrontOnEmptyQueue() {
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org.junit.jupiter.api.Assertions.assertThrows(NoSuchElementException.class, () -> queue.peekFront(), "Peeking front on an empty queue should throw NoSuchElementException.");
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}
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@Test
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void testPeekRearOnEmptyQueue() {
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org.junit.jupiter.api.Assertions.assertThrows(NoSuchElementException.class, () -> queue.peekRear(), "Peeking rear on an empty queue should throw NoSuchElementException.");
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}
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@Test
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void testPeekFront() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals(10, queue.peekFront(), "Peek front should return the first enqueued element.");
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assertEquals(10, queue.peekFront(), "Peek front should not remove the element.");
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assertEquals(3, queue.size(), "Queue size should remain unchanged after peek.");
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}
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@Test
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void testPeekRear() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals(30, queue.peekRear(), "Peek rear should return the last enqueued element.");
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assertEquals(30, queue.peekRear(), "Peek rear should not remove the element.");
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assertEquals(3, queue.size(), "Queue size should remain unchanged after peek.");
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}
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@Test
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void testPeekAtPosition() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals(10, queue.peek(1), "Peek at position 1 should return the first enqueued element.");
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assertEquals(20, queue.peek(2), "Peek at position 2 should return the second enqueued element.");
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assertEquals(30, queue.peek(3), "Peek at position 3 should return the third enqueued element.");
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}
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@Test
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void testPeekAtInvalidPosition() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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org.junit.jupiter.api.Assertions.assertThrows(IndexOutOfBoundsException.class, () -> queue.peek(4), "Peeking at a position greater than size should throw IndexOutOfBoundsException.");
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org.junit.jupiter.api.Assertions.assertThrows(IndexOutOfBoundsException.class, () -> queue.peek(0), "Peeking at position 0 should throw IndexOutOfBoundsException.");
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}
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@Test
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void testClearQueue() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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queue.clear();
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assertTrue(queue.isEmpty(), "Queue should be empty after clear.");
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assertEquals(0, queue.size(), "Queue size should be 0 after clear.");
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}
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@Test
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void testIterator() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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Iterator<Integer> it = queue.iterator();
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assertTrue(it.hasNext(), "Iterator should have next element.");
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assertEquals(10, it.next(), "First iterator value should be the first enqueued element.");
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assertEquals(20, it.next(), "Second iterator value should be the second enqueued element.");
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assertEquals(30, it.next(), "Third iterator value should be the third enqueued element.");
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assertFalse(it.hasNext(), "Iterator should not have next element after last element.");
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org.junit.jupiter.api.Assertions.assertThrows(NoSuchElementException.class, it::next, "Calling next() on exhausted iterator should throw NoSuchElementException.");
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}
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@Test
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void testToString() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals("[10, 20, 30]", queue.toString(), "toString should return a properly formatted string representation of the queue.");
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}
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@Test
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void testEnqueueAfterDequeue() {
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queue.enqueue(10);
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queue.enqueue(20);
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queue.enqueue(30);
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assertEquals(10, queue.dequeue(), "Dequeued element should be 10.");
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assertEquals(20, queue.dequeue(), "Dequeued element should be 20.");
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queue.enqueue(40);
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assertEquals(30, queue.peekFront(), "Peek front should return 30 after dequeuing and enqueuing new elements.");
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assertEquals(40, queue.peekRear(), "Peek rear should return 40 after enqueuing new elements.");
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}
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@Test
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void testQueueMaintainsOrder() {
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for (int i = 1; i <= 100; i++) {
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queue.enqueue(i);
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}
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assertEquals(queue.peekRear(), 4);
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assertEquals(queue.peek(2), 2);
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for (int i = 1; i <= 100; i++) {
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assertEquals(i, queue.dequeue(), "Queue should maintain the correct order of elements.");
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}
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assertEquals(queue.peek(4), 4);
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assertTrue(queue.isEmpty(), "Queue should be empty after dequeuing all elements.");
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}
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final int[] element = {1};
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@Test
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void testSizeAfterOperations() {
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assertEquals(0, queue.size(), "Initial queue size should be 0.");
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// iterates over all the elements present
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// as in the form of nodes
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queue.forEach(integer -> {
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if (element[0]++ != integer) {
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throw new AssertionError();
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}
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});
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queue.enqueue(10);
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assertEquals(1, queue.size(), "Queue size should be 1 after one enqueue.");
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queue.enqueue(20);
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assertEquals(2, queue.size(), "Queue size should be 2 after two enqueues.");
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queue.dequeue();
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assertEquals(1, queue.size(), "Queue size should be 1 after one dequeue.");
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queue.clear();
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assertEquals(0, queue.size(), "Queue size should be 0 after clear.");
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}
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@Test
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void testQueueToStringOnEmptyQueue() {
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assertEquals("[]", queue.toString(), "toString on empty queue should return '[]'.");
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}
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@Test
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void testEnqueueNull() {
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org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> queue.enqueue(null), "Cannot enqueue null data.");
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}
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@Test
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void testIteratorOnEmptyQueue() {
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Iterator<Integer> it = queue.iterator();
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assertFalse(it.hasNext(), "Iterator on empty queue should not have next element.");
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org.junit.jupiter.api.Assertions.assertThrows(NoSuchElementException.class, it::next, "Calling next() on empty queue iterator should throw NoSuchElementException.");
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}
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}
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