QueueUsingTwoStacksTest.java

packagecom.thealgorithms.others;

importstaticorg.junit.jupiter.api.Assertions.assertEquals;
importstaticorg.junit.jupiter.api.Assertions.assertFalse;
importstaticorg.junit.jupiter.api.Assertions.assertTrue;

importjava.util.EmptyStackException;
importorg.junit.jupiter.api.BeforeEach;
importorg.junit.jupiter.api.Test;

classQueueUsingTwoStacksTest {

privateQueueUsingTwoStacksqueue;

@BeforeEach
voidsetUp() {
queue = newQueueUsingTwoStacks();
 }

@Test
voidtestIsEmptyInitially() {
assertTrue(queue.isEmpty(), "Queue should be empty initially");
 }

@Test
voidtestInsertSingleElement() {
queue.insert(1);
assertFalse(queue.isEmpty(), "Queue should not be empty after inserting an element");
assertEquals(1, queue.peekFront(), "The front element should be the inserted element");
 }

@Test
voidtestRemoveSingleElement() {
queue.insert(1);
assertEquals(1, queue.remove(), "Removing should return the first inserted element");
assertTrue(queue.isEmpty(), "Queue should be empty after removing the only element");
 }

@Test
voidtestRemoveMultipleElements() {
queue.insert(1);
queue.insert(2);
queue.insert(3);
assertEquals(1, queue.remove(), "First removed element should be the first inserted element");
assertEquals(2, queue.remove(), "Second removed element should be the second inserted element");
assertEquals(3, queue.remove(), "Third removed element should be the third inserted element");
assertTrue(queue.isEmpty(), "Queue should be empty after removing all elements");
 }

@Test
voidtestPeekFrontWithMultipleElements() {
queue.insert(1);
queue.insert(2);
queue.insert(3);
assertEquals(1, queue.peekFront(), "The front element should be the first inserted element");
 }

@Test
voidtestPeekBackWithMultipleElements() {
queue.insert(1);
queue.insert(2);
queue.insert(3);
assertEquals(3, queue.peekBack(), "The back element should be the last inserted element");
 }

@Test
voidtestPeekFrontAfterRemovals() {
queue.insert(1);
queue.insert(2);
queue.insert(3);
queue.remove();
assertEquals(2, queue.peekFront(), "After removing one element, the front should be the second element");
 }

@Test
voidtestIsEmptyAfterRemovals() {
queue.insert(1);
queue.insert(2);
queue.remove();
queue.remove();
assertTrue(queue.isEmpty(), "Queue should be empty after removing all elements");
 }

@Test
voidtestRemoveFromEmptyQueue() {
org.junit.jupiter.api.Assertions.assertThrows(EmptyStackException.class, queue::remove, "Removing from an empty queue should throw an exception");
 }

@Test
voidtestPeekFrontFromEmptyQueue() {
org.junit.jupiter.api.Assertions.assertThrows(EmptyStackException.class, queue::peekFront, "Peeking front from an empty queue should throw an exception");
 }

@Test
voidtestPeekBackFromEmptyQueue() {
org.junit.jupiter.api.Assertions.assertThrows(EmptyStackException.class, queue::peekBack, "Peeking back from an empty queue should throw an exception");
 }

@Test
voidtestIsInStackEmptyInitially() {
assertTrue(queue.isInStackEmpty(), "inStack should be empty initially");
 }

@Test
voidtestIsOutStackEmptyInitially() {
assertTrue(queue.isOutStackEmpty(), "outStack should be empty initially");
 }

@Test
voidtestIsInStackEmptyAfterInsertion() {
queue.insert(1);
assertFalse(queue.isInStackEmpty(), "inStack should not be empty after an insertion");
 }

@Test
voidtestIsOutStackEmptyAfterInsertion() {
queue.insert(1);
assertTrue(queue.isOutStackEmpty(), "outStack should still be empty after an insertion");
 }

@Test
voidtestIsOutStackEmptyAfterRemoval() {
queue.insert(1);
queue.remove();
assertTrue(queue.isOutStackEmpty(), "outStack should be empty after removing the only element");
 }

@Test
voidtestIsInStackEmptyAfterMultipleRemovals() {
queue.insert(1);
queue.insert(2);
queue.remove();
queue.remove();
assertTrue(queue.isInStackEmpty(), "inStack should be empty after removing all elements");
 }

@Test
voidtestIsOutStackEmptyAfterMultipleRemovals() {
queue.insert(1);
queue.insert(2);
queue.remove();
queue.remove();
assertTrue(queue.isOutStackEmpty(), "outStack should be empty after removing all elements");
 }
}