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BAEL-1310: Code for Quick Guide to Stack. (eugenp#2993)
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‎core-java/src/test/java/com/baeldung/stack/StackUnitTest.java‎

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package com.baeldung.stack;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.junit.Assert.*;
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import java.util.Arrays;
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import java.util.List;
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import java.util.ListIterator;
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import java.util.Stack;
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import org.junit.Test;
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public class StackUnitTest {
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@Test
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public void whenStackIsCreated_thenItHasSize0() {
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Stack intStack = new Stack();
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assertEquals(0, intStack.size());
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}
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@Test
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public void givenEmptyStack_whenElementIsPushed_thenStackSizeisIncreased() {
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Stack intStack = new Stack();
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intStack.push(1);
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assertEquals(1, intStack.size());
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}
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@Test
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public void givenEmptyStack_whenMultipleElementsArePushed_thenStackSizeisIncreased() {
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Stack intStack = new Stack();
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List<Integer> intList = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
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boolean result = intStack.addAll(intList);
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assertTrue(result);
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assertEquals(7, intList.size());
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}
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@Test
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public void whenElementIsPoppedFromStack_thenElementIsRemovedAndSizeChanges() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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intStack.pop();
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assertTrue(intStack.isEmpty());
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}
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@Test
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public void whenElementIsPeeked_thenElementIsNotRemovedAndSizeDoesNotChange() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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intStack.peek();
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assertEquals(1, intStack.search(5));
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assertEquals(1, intStack.size());
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}
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@Test
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public void whenElementIsOnStack_thenSearchReturnsItsDistanceFromTheTop() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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assertEquals(1, intStack.search(5));
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}
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@Test
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public void whenElementIsOnStack_thenIndexOfReturnsItsIndex() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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int indexOf = intStack.indexOf(5);
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assertEquals(0, indexOf);
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}
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@Test
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public void whenMultipleElementsAreOnStack_thenIndexOfReturnsLastElementIndex() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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intStack.push(5);
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intStack.push(5);
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int lastIndexOf = intStack.lastIndexOf(5);
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assertEquals(2, lastIndexOf);
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}
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@Test
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public void givenElementOnStack_whenRemoveElementIsInvoked_thenElementIsRemoved() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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intStack.push(5);
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intStack.removeElement(5);
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assertEquals(1, intStack.size());
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}
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@Test
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public void givenElementOnStack_whenRemoveElementAtIsInvoked_thenElementIsRemoved() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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intStack.push(7);
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intStack.removeElementAt(1);
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assertEquals(-1, intStack.search(7));
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}
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@Test
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public void givenElementsOnStack_whenRemoveAllElementsIsInvoked_thenAllElementsAreRemoved() {
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Stack<Integer> intStack = new Stack();
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intStack.push(5);
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intStack.push(7);
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intStack.removeAllElements();
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assertTrue(intStack.isEmpty());
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}
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@Test
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public void givenElementsOnStack_whenRemoveAllIsInvoked_thenAllElementsFromCollectionAreRemoved() {
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Stack<Integer> intStack = new Stack();
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List<Integer> intList = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
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intStack.addAll(intList);
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intStack.add(500);
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intStack.removeAll(intList);
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assertEquals(1, intStack.size());
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}
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@Test
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public void givenElementsOnStack_whenRemoveIfIsInvoked_thenAllElementsSatysfyingConditionAreRemoved() {
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Stack<Integer> intStack = new Stack();
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List<Integer> intList = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
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intStack.addAll(intList);
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intStack.removeIf(element -> element < 6);
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assertEquals(2, intStack.size());
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}
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@Test
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public void whenAnotherStackCreatedWhileTraversingStack_thenStacksAreEqual() {
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Stack<Integer> intStack = new Stack<>();
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List<Integer> intList = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
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intStack.addAll(intList);
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ListIterator<Integer> it = intStack.listIterator();
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Stack<Integer> result = new Stack();
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while(it.hasNext()) {
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result.push(it.next());
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}
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assertThat(result, equalTo(intStack));
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}
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}

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