diff --git a/src/test/java/com/thealgorithms/stacks/MinStackUsingTwoStacksTest.java b/src/test/java/com/thealgorithms/stacks/MinStackUsingTwoStacksTest.java index e5deb17e9a8f..36bdde49b235 100644 --- a/src/test/java/com/thealgorithms/stacks/MinStackUsingTwoStacksTest.java +++ b/src/test/java/com/thealgorithms/stacks/MinStackUsingTwoStacksTest.java @@ -1,38 +1,112 @@ package com.thealgorithms.stacks; import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertThrows; +import java.util.EmptyStackException; import org.junit.jupiter.api.Test; public class MinStackUsingTwoStacksTest { @Test - public void testMinStackOperations() { + public void testBasicOperations() { MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); minStack.push(3); minStack.push(5); - assertEquals(3, minStack.getMin()); + assertEquals(3, minStack.getMin(), "Min should be 3"); minStack.push(2); minStack.push(1); - assertEquals(1, minStack.getMin()); + assertEquals(1, minStack.getMin(), "Min should be 1"); minStack.pop(); - assertEquals(2, minStack.getMin()); + assertEquals(2, minStack.getMin(), "Min should be 2 after popping 1"); + + assertEquals(2, minStack.top(), "Top should be 2"); + } + + @Test + public void testPushDuplicateMins() { + MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + minStack.push(2); + minStack.push(2); + minStack.push(1); + minStack.push(1); + assertEquals(1, minStack.getMin(), "Min should be 1"); + + minStack.pop(); + assertEquals(1, minStack.getMin(), "Min should still be 1 after popping one 1"); + + minStack.pop(); + assertEquals(2, minStack.getMin(), "Min should be 2 after popping both 1s"); + + minStack.pop(); + assertEquals(2, minStack.getMin(), "Min should still be 2 after popping one 2"); + + minStack.pop(); + // Now stack is empty, expect exception on getMin + assertThrows(EmptyStackException.class, minStack::getMin); } @Test - public void testMinStackOperations2() { + public void testPopOnEmptyStack() { MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + assertThrows(EmptyStackException.class, minStack::pop); + } + + @Test + public void testTopOnEmptyStack() { + MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + assertThrows(EmptyStackException.class, minStack::top); + } + + @Test + public void testGetMinOnEmptyStack() { + MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + assertThrows(EmptyStackException.class, minStack::getMin); + } + + @Test + public void testSingleElementStack() { + MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + minStack.push(10); + assertEquals(10, minStack.getMin()); + assertEquals(10, minStack.top()); + + minStack.pop(); + assertThrows(EmptyStackException.class, minStack::getMin); + } + + @Test + public void testIncreasingSequence() { + MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + minStack.push(1); + minStack.push(2); minStack.push(3); - minStack.push(5); - assertEquals(3, minStack.getMin()); + minStack.push(4); + + assertEquals(1, minStack.getMin()); + assertEquals(4, minStack.top()); + + minStack.pop(); + minStack.pop(); + assertEquals(1, minStack.getMin()); + assertEquals(2, minStack.top()); + } + @Test + public void testDecreasingSequence() { + MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks(); + minStack.push(4); + minStack.push(3); minStack.push(2); minStack.push(1); + assertEquals(1, minStack.getMin()); + assertEquals(1, minStack.top()); minStack.pop(); assertEquals(2, minStack.getMin()); + assertEquals(2, minStack.top()); } }