using System;

using Microsoft.VisualStudio.TestTools.UnitTesting;

using System.DirectoryServices.AccountManagement;

using System.Reflection;

​

public class AuthenticationService

{

    public bool AuthenticateUser(string username, string password)

    {

        try

        {

            // Replace with your actual AD domain

            string domain = "corp.example.com";

​

            // ContextType can be Domain, ApplicationDirectory, or Machine

            using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, domain))

            {

                // Validate the credentials

                return pc.ValidateCredentials(username, password);

            }

        }

        catch

        {

            // Catch any exceptions during authentication and return false

            return false;

        }

    }

    public static void Main()

    {

        Type testClassType = typeof(AuthenticationServiceTests); // Get test class type

        object testClassInstance = Activator.CreateInstance(testClassType); // Create test class instance

        MethodInfo[] methods = testClassType.GetMethods(); // Get all methods

​

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

​

        foreach (MethodInfo method in methods)

        {

            if (method.GetCustomAttribute<TestMethodAttribute>() != null) // Check for [TestMethod]

            {

                try

                {

                    method.Invoke(testClassInstance, null); // Invoke test method

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

                }

                catch (TargetInvocationException ex)

                {

                    Console.WriteLine($"✘ {method.Name} FAILED - {ex.InnerException.Message}");

                }

            }

        }

​

        Console.WriteLine("\nTest execution complete.");

    }

}

​

[TestClass]

public class AuthenticationServiceTests

{

    [TestMethod]

    public void AuthenticateUser_ValidCredentials_ReturnsTrue()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

​

        // Simulate AD user.  In real implementation, these would be actual AD users.

        //For testing purposes these credential would exists in AD

        string username = "validuser";

        string password = "validpassword";

​

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsTrue(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_InvalidUsername_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = "invaliduser";

        string password = "anypassword";

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_InvalidPassword_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = "validuser";

        string password = "invalidpassword";

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_EmptyUsername_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = "";

        string password = "anypassword";

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_EmptyPassword_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = "validuser";

        string password = "";

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_NullUsername_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = null;

        string password = "anypassword";

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_NullPassword_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = "validuser";

        string password = null;

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

​

    [TestMethod]

    public void AuthenticateUser_UsernameWithSpecialCharacters_ReturnsFalse()

    {

        // Arrange

        AuthenticationService authService = new AuthenticationService();

        string username = "user@with$special#chars";

        string password = "anypassword";

​

        // Act

        bool result = authService.AuthenticateUser(username, password);

​

        // Assert

        Assert.IsFalse(result);

    }

}