using Microsoft.VisualStudio.TestTools.UnitTesting;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Running tests...\n");

​

        Type testClassType = typeof(UserManagementTests);

        object testInstance = Activator.CreateInstance(testClassType);

​

        // Get all methods with [TestMethod] attribute

        MethodInfo[] testMethods = testClassType.GetMethods()

            .Where(m => m.GetCustomAttributes(typeof(TestMethodAttribute), false).Length > 0)

            .ToArray();

​

        int passed = 0, failed = 0;

​

        foreach (var method in testMethods)

        {

            try

            {

                method.Invoke(testInstance, null);

                Console.WriteLine($"✅ {method.Name} PASSED");

                passed++;

            }

            catch (Exception ex)

            {

                Console.WriteLine($"❌ {method.Name} FAILED: {ex.InnerException?.Message ?? ex.Message}");

                failed++;

            }

        }

​

        Console.WriteLine($"\nTests Completed: {passed + failed} Total, {passed} Passed, {failed} Failed.");

    }

}

​

​

​

public class UserManagement

{

    private readonly HashSet<string> _userIDs = new HashSet<string>();

​

    /// <summary>

    /// Adds a user ID to the collection if it's unique.

    /// </summary>

    /// <param name="userId">The user ID to add.</param>

    /// <returns>True if the user ID was added, false if it already exists.</returns>

    public bool AddUser(string userId)

    {

        if (string.IsNullOrWhiteSpace(userId))

        {

            return false;

        }

​

        return _userIDs.Add(userId);

    }

}

​

​

[TestClass]

public class UserManagementTests

{

    [TestMethod]

    public void AddUser_ValidUserId_ReturnsTrue()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser("user123");

        Assert.IsTrue(result);

    }

​

    [TestMethod]

    public void AddUser_DuplicateUserId_ReturnsFalse()

    {

        UserManagement userManagement = new UserManagement();

        userManagement.AddUser("user123");

        bool result = userManagement.AddUser("user123");

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AddUser_EmptyUserId_ReturnsFalse()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser("");

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AddUser_NullUserId_ReturnsFalse()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser(null);

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AddUser_WhiteSpaceUserId_ReturnsFalse()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser("   ");

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AddUser_MultipleUniqueUserIds_ReturnsTrue()

    {

        UserManagement userManagement = new UserManagement();

        Assert.IsTrue(userManagement.AddUser("user1"));

        Assert.IsTrue(userManagement.AddUser("user2"));

        Assert.IsTrue(userManagement.AddUser("user3"));

    }

​

    [TestMethod]

    public void AddUser_UserIdWithSpecialCharacters_ReturnsTrue()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser("user!@#$%^");

        Assert.IsTrue(result);

    }

​

    [TestMethod]

    public void AddUser_UserIdWithUnicodeCharacters_ReturnsTrue()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser("user你好世界");

        Assert.IsTrue(result);

    }

​

    [TestMethod]

    public void AddUser_LongUserId_ReturnsTrue()

    {

        UserManagement userManagement = new UserManagement();

        string longUserId = new string('a', 1000); // Create a long user ID

        bool result = userManagement.AddUser(longUserId);

        Assert.IsTrue(result);

    }

    [TestMethod]

    public void AddUser_UserIdWithLeadingAndTrailingSpaces_ReturnsTrue()

    {

        UserManagement userManagement = new UserManagement();

        bool result = userManagement.AddUser("  user123  ");

        Assert.IsTrue(result);

​

    }

}