using NUnit.Framework;

using System;

​

[TestFixture]

public class PalindromeCheckerTests

{

    private PalindromeChecker _palindromeChecker;

​

    [SetUp]

    public void Setup()

    {

        _palindromeChecker = new PalindromeChecker();

    }

​

    [Test]

    public void IsPalindrome_ValidPalindromeString_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("madam"));

    }

​

    [Test]

    public void IsPalindrome_ValidPalindromeNumber_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("121"));

    }

​

    [Test]

    public void IsPalindrome_NonPalindromeString_ReturnsFalse()

    {

        Assert.IsFalse(_palindromeChecker.IsPalindrome("welcome"));

    }

​

    [Test]

    public void IsPalindrome_PalindromeWithSpaces_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("race car"));

    }

​

     [Test]

    public void IsPalindrome_PalindromeWithPunctuation_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("A man, a plan, a canal: Panama"));

    }

​

    [Test]

    public void IsPalindrome_EmptyString_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome(""));

    }

​

    [Test]

    public void IsPalindrome_SingleCharacter_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("a"));

    }

​

    [Test]

    public void IsPalindrome_MixedCasePalindrome_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("Racecar"));

    }

​

    [Test]

    public void IsPalindrome_NumberWithLeadingZeros_ReturnsFalse()

    {

        Assert.IsFalse(_palindromeChecker.IsPalindrome("001"));

    }

​

    [Test]

    public void IsPalindrome_WhitespaceOnly_ThrowsArgumentException()

    {

        Assert.Throws<ArgumentException>(() => _palindromeChecker.IsPalindrome("   "));

    }

​

    [Test]

    public void IsPalindrome_NullInput_ThrowsArgumentNullException()

    {

        Assert.Throws<ArgumentNullException>(() => _palindromeChecker.IsPalindrome(null));

    }

​

    [Test]

    public void IsPalindrome_LongPalindrome_ReturnsTrue()

    {

        string longPalindrome = new string('a', 1000) + "bb" + new string('a', 1000);

        Assert.IsTrue(_palindromeChecker.IsPalindrome(longPalindrome));

    }

​

    [Test]

        public void IsPalindrome_StringWithSpecialCharacters_ReturnsTrue()

    {

        Assert.IsTrue(_palindromeChecker.IsPalindrome("Kayak!"));

    }

}