public void RemoveSecondFromLastTest()
{
// arrange
var head = new ListNode(1)
{
Next = new ListNode(2)
{
Next = new ListNode(3)
{
Next = new ListNode(4)
{
Next = new ListNode(5)
}
}
}
};
// act
int secondFromLast = 2; // second from last is 4
int expectedNodeValueToRemove = 4;
ListNode newHead = RemoveNthFromLastNodeInList.RemoveTheNthFromEnd(head, secondFromLast);
// assert
Assert.AreEqual(head, newHead);
ListNode currElem = newHead;
while (currElem != null)
{
Assert.AreNotEqual(expectedNodeValueToRemove, currElem.Val);
currElem = currElem.Next;
}
}
public void RemoveHeadTest()
{
// arrange
ListNode singleElem = new ListNode(1);
// act
ListNode newHead = RemoveNthFromLastNodeInList.RemoveTheNthFromEnd(singleElem, 1);
// assert
Assert.IsNull(newHead); // make sure the list is now empty
}
public void NoChangesWhenNIsLargerThanLISize()
{
// arrange
var head = new ListNode(1);
// act + assert
int twoElems = 2; // this list has only 1 element and we want to remove the 2nd from the last (which doesn't exist)
Assert.ThrowsException <ArgumentException>(
() => RemoveNthFromLastNodeInList.RemoveTheNthFromEnd(head, twoElems)
);
}
public void NoChangesWhenNIsZero()
{
// arrange
var head = new ListNode(1);
// act
int zeroIdx = 0;
ListNode newHead = RemoveNthFromLastNodeInList.RemoveTheNthFromEnd(head, zeroIdx);
// assert
Assert.IsNotNull(newHead);
Assert.AreEqual(head, newHead);
Assert.AreEqual(1, newHead.Val);
}
