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testing: improve SortStackTest (#6422)

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testing: improve SortStackTest

Co-authored-by: Deniz Altunkapan <93663085+DenizAltunkapan@users.noreply.github.com>
This commit is contained in:
Oleksandr Klymenko
2025-07-23 17:09:18 +02:00
committed by GitHub
parent 073b6f15a8
commit 7e3fbae1a4
1 changed files with 183 additions and 0 deletions
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183
src/test/java/com/thealgorithms/stacks/SortStackTest.java
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@@ -74,4 +74,187 @@ public class SortStackTest {
assertEquals(2, (int) stack.pop());
assertEquals(1, (int) stack.pop());
}
@Test
public void testSortReverseSortedStack() {
// Test worst case scenario - completely reverse sorted
stack.push(5);
stack.push(4);
stack.push(3);
stack.push(2);
stack.push(1);
SortStack.sortStack(stack);
assertEquals(5, stack.size());
assertEquals(5, (int) stack.pop());
assertEquals(4, (int) stack.pop());
assertEquals(3, (int) stack.pop());
assertEquals(2, (int) stack.pop());
assertEquals(1, (int) stack.pop());
}
@Test
public void testSortWithAllSameElements() {
// Test stack with all identical elements
stack.push(7);
stack.push(7);
stack.push(7);
stack.push(7);
SortStack.sortStack(stack);
assertEquals(4, stack.size());
assertEquals(7, (int) stack.pop());
assertEquals(7, (int) stack.pop());
assertEquals(7, (int) stack.pop());
assertEquals(7, (int) stack.pop());
}
@Test
public void testSortWithNegativeNumbers() {
// Test with negative numbers
stack.push(-3);
stack.push(1);
stack.push(-5);
stack.push(2);
stack.push(-1);
SortStack.sortStack(stack);
assertEquals(5, stack.size());
assertEquals(2, (int) stack.pop());
assertEquals(1, (int) stack.pop());
assertEquals(-1, (int) stack.pop());
assertEquals(-3, (int) stack.pop());
assertEquals(-5, (int) stack.pop());
}
@Test
public void testSortWithAllNegativeNumbers() {
// Test with only negative numbers
stack.push(-10);
stack.push(-5);
stack.push(-15);
stack.push(-1);
SortStack.sortStack(stack);
assertEquals(4, stack.size());
assertEquals(-1, (int) stack.pop());
assertEquals(-5, (int) stack.pop());
assertEquals(-10, (int) stack.pop());
assertEquals(-15, (int) stack.pop());
}
@Test
public void testSortWithZero() {
// Test with zero included
stack.push(3);
stack.push(0);
stack.push(-2);
stack.push(1);
SortStack.sortStack(stack);
assertEquals(4, stack.size());
assertEquals(3, (int) stack.pop());
assertEquals(1, (int) stack.pop());
assertEquals(0, (int) stack.pop());
assertEquals(-2, (int) stack.pop());
}
@Test
public void testSortLargerStack() {
// Test with a larger number of elements
int[] values = {15, 3, 9, 1, 12, 6, 18, 4, 11, 8};
for (int value : values) {
stack.push(value);
}
SortStack.sortStack(stack);
assertEquals(10, stack.size());
// Verify sorted order (largest to smallest when popping)
int[] expectedOrder = {18, 15, 12, 11, 9, 8, 6, 4, 3, 1};
for (int expected : expectedOrder) {
assertEquals(expected, (int) stack.pop());
}
}
@Test
public void testSortTwoElements() {
// Test edge case with exactly two elements
stack.push(5);
stack.push(2);
SortStack.sortStack(stack);
assertEquals(2, stack.size());
assertEquals(5, (int) stack.pop());
assertEquals(2, (int) stack.pop());
}
@Test
public void testSortTwoElementsAlreadySorted() {
// Test two elements already in correct order
stack.push(2);
stack.push(5);
SortStack.sortStack(stack);
assertEquals(2, stack.size());
assertEquals(5, (int) stack.pop());
assertEquals(2, (int) stack.pop());
}
@Test
public void testSortStackWithMinAndMaxValues() {
// Test with Integer.MAX_VALUE and Integer.MIN_VALUE
stack.push(0);
stack.push(Integer.MAX_VALUE);
stack.push(Integer.MIN_VALUE);
stack.push(100);
SortStack.sortStack(stack);
assertEquals(4, stack.size());
assertEquals(Integer.MAX_VALUE, (int) stack.pop());
assertEquals(100, (int) stack.pop());
assertEquals(0, (int) stack.pop());
assertEquals(Integer.MIN_VALUE, (int) stack.pop());
}
@Test
public void testSortWithManyDuplicates() {
// Test with multiple sets of duplicates
stack.push(3);
stack.push(1);
stack.push(3);
stack.push(1);
stack.push(2);
stack.push(2);
stack.push(3);
SortStack.sortStack(stack);
assertEquals(7, stack.size());
assertEquals(3, (int) stack.pop());
assertEquals(3, (int) stack.pop());
assertEquals(3, (int) stack.pop());
assertEquals(2, (int) stack.pop());
assertEquals(2, (int) stack.pop());
assertEquals(1, (int) stack.pop());
assertEquals(1, (int) stack.pop());
}
@Test
public void testOriginalStackIsModified() {
// Verify that the original stack is modified, not a copy
Stack<Integer> originalReference = stack;
stack.push(3);
stack.push(1);
stack.push(2);
SortStack.sortStack(stack);
// Verify it's the same object reference
assertTrue(stack == originalReference);
assertEquals(3, stack.size());
assertEquals(3, (int) stack.pop());
assertEquals(2, (int) stack.pop());
assertEquals(1, (int) stack.pop());
}
}