coding-practice/problems/3227-vowels-game-in-a-string/test/SolutionTests.cs

// LeetCode 3227: Vowels Game in a String 單元測試（xUnit）
// Problem: Alice and Bob play a game. Alice removes substrings with odd vowels, 
// Bob removes substrings with even vowels. Alice wins if string has any vowels.

using Xunit;

public class SolutionTests 
{
    private readonly Solution _s = new Solution();

    [Fact]
    public void Example1_StringWithVowels_AliceWins()
    {
        // Arrange
        var input = "leetcode"; // contains vowels: e,e,o,e
        var expected = true; // Alice wins
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void Example2_StringWithoutVowels_BobWins()
    {
        // Arrange
        var input = "bcdf"; // no vowels
        var expected = false; // Bob wins (Alice can't make first move)
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void AllVowels_AliceWins()
    {
        // Arrange
        var input = "aeiou"; // all vowels (odd count = 5)
        var expected = true; // Alice removes entire string
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void SingleVowel_AliceWins()
    {
        // Arrange
        var input = "a"; // single vowel
        var expected = true; // Alice removes it immediately
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void SingleConsonant_BobWins()
    {
        // Arrange
        var input = "b"; // single consonant, no vowels
        var expected = false; // Alice can't move
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void MixedString_EvenVowelCount_AliceWins()
    {
        // Arrange
        var input = "programming"; // vowels: o,a,i (3 vowels, odd)
        var expected = true; // Alice can remove all vowels at once
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void LongStringNoVowels_BobWins()
    {
        // Arrange
        var input = "bcdfghjklmnpqrstvwxyz"; // all consonants
        var expected = false; // No vowels = Bob wins
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void RepeatedVowels_AliceWins()
    {
        // Arrange
        var input = "aaaa"; // 4 vowels (even count)
        var expected = true; // Alice can remove 3, leaving 1 (Bob can't move)
        
        // Act
        var got = _s.DoesAliceWin(input);
        
        // Assert
        Assert.Equal(expected, got);
    }

    [Fact]
    public void EdgeCases()
    {
        // Single character tests
        Assert.True(_s.DoesAliceWin("e")); // vowel
        Assert.False(_s.DoesAliceWin("x")); // consonant
        
        // Two character tests
        Assert.True(_s.DoesAliceWin("ab")); // has vowel 'a'
        Assert.False(_s.DoesAliceWin("xy")); // no vowels
        
        // Vowel at different positions
        Assert.True(_s.DoesAliceWin("xabc")); // vowel at start-middle
        Assert.True(_s.DoesAliceWin("abcx")); // vowel in middle
        Assert.True(_s.DoesAliceWin("xbca")); // vowel at end
    }

    [Fact]
    public void GameTheoryValidation()
    {
        // Test cases that validate the game theory logic:
        // If total vowels = 0: Alice loses (can't make first move)
        Assert.False(_s.DoesAliceWin("bcdfg"));
        
        // If total vowels = odd: Alice wins (removes all vowels in one move)
        Assert.True(_s.DoesAliceWin("hello")); // e,o = 2 vowels (even), but Alice still wins
        Assert.True(_s.DoesAliceWin("beautiful")); // e,a,u,i,u = 5 vowels (odd)
        
        // If total vowels = even > 0: Alice wins (leaves exactly 1 vowel for Bob)
        Assert.True(_s.DoesAliceWin("code")); // o,e = 2 vowels (even)
        Assert.True(_s.DoesAliceWin("education")); // e,u,a,i,o = 5 vowels, but any vowels = Alice wins
    }

    [Theory]
    [InlineData("", false)]  // empty string - no vowels
    [InlineData("aeiou", true)]  // all vowels
    [InlineData("bcdfg", false)]  // all consonants  
    [InlineData("hello", true)]  // mixed with vowels
    [InlineData("rhythm", false)]  // no vowels (y not considered vowel)
    [InlineData("queue", true)]  // multiple same vowels
    public void ParameterizedTests(string input, bool expected)
    {
        // Act & Assert
        Assert.Equal(expected, _s.DoesAliceWin(input));
    }
}