DeutschLernen/Tests/Unit/Domain/Entities/UserTests.cs

using System;
using GermanApp.Domain.Entities;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace GermanApp.Tests.Unit.Domain.Entities;

/// <summary>
/// Unit tests for User domain entity.
/// Tests the user factory methods and business logic.
/// </summary>
[TestClass]
public class UserTests
{
    #region Factory Method Tests

    [TestMethod]
    [TestCategory("Factory")]
    public void Create_WithValidParameters_ReturnsUser()
    {
        // Arrange
        string username = "testuser";
        string email = "test@example.com";
        string passwordHash = "hashed-password";

        // Act
        var user = User.Create(username, email, passwordHash);

        // Assert
        Assert.IsNotNull(user);
        Assert.AreEqual(username, user.Username);
        Assert.AreEqual(email, user.Email);
        Assert.AreEqual(passwordHash, user.PasswordHash);
        Assert.AreEqual("A1", user.CurrentLevel);
        Assert.AreEqual(0, user.Streak);
        Assert.AreEqual(0, user.TotalPoints);
        Assert.IsNotNull(user.CreatedAt);
        Assert.IsTrue(user.CreatedAt <= DateTime.UtcNow);
    }

    [TestMethod]
    [TestCategory("Factory")]
    public void Create_WithEmptyPasswordHash_ReturnsUser()
    {
        // Arrange
        string username = "testuser";
        string email = "test@example.com";
        string passwordHash = "";

        // Act
        var user = User.Create(username, email, passwordHash);

        // Assert
        Assert.IsNotNull(user);
        Assert.AreEqual(passwordHash, user.PasswordHash);
    }

    [TestMethod]
    [TestCategory("Factory")]
    public void Create_LowercasesEmail()
    {
        // Arrange
        string username = "testuser";
        string email = "TEST@EXAMPLE.COM";
        string passwordHash = "hashed-password";

        // Act
        var user = User.Create(username, email, passwordHash);

        // Assert
        Assert.AreEqual("test@example.com", user.Email);
    }

    [TestMethod]
    [TestCategory("Factory")]
    public void Create_WithMixedCaseUsername_PreservesUsernameCase()
    {
        // Arrange
        string username = "TestUser123";
        string email = "test@example.com";
        string passwordHash = "hashed-password";

        // Act
        var user = User.Create(username, email, passwordHash);

        // Assert
        Assert.AreEqual(username, user.Username);
    }

    #endregion

    #region ChangePassword Method Tests

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangePassword_WithValidHash_UpdatesPassword()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "initial-hash");
        string newHash = "new-hashed-password";

        // Act
        user.ChangePassword(newHash);

        // Assert
        Assert.AreEqual(newHash, user.PasswordHash);
    }

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangePassword_WithEmptyHash_UpdatesPassword()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "initial-hash");

        // Act
        user.ChangePassword("");

        // Assert
        Assert.AreEqual("", user.PasswordHash);
    }

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangePassword_MultipleTimes_UpdatesCorrectly()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash1");

        // Act
        user.ChangePassword("hash2");
        user.ChangePassword("hash3");

        // Assert
        Assert.AreEqual("hash3", user.PasswordHash);
    }

    #endregion

    #region ChangeEmail Method Tests

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangeEmail_WithValidEmail_UpdatesEmail()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");
        var newEmail = "new@example.com";

        // Act
        user.ChangeEmail(newEmail);

        // Assert
        Assert.AreEqual("new@example.com", user.Email);
    }

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangeEmail_LowercasesEmail()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.ChangeEmail("UPPERCASE@EXAMPLE.COM");

        // Assert
        Assert.AreEqual("uppercase@example.com", user.Email);
    }

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangeEmail_WithMixedCase_Values()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.ChangeEmail("TeSt@ExAmPlE.cOm");

        // Assert
        Assert.AreEqual("test@example.com", user.Email);
    }

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangeEmail_WithNullEmail_UpdatesEmailToEmpty()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act - Note: This won't throw, it will just set to empty string
        user.ChangeEmail(null!);

        // Assert
        Assert.AreEqual("", user.Email);
    }

    [TestMethod]
    [TestCategory("Behavior")]
    public void ChangeEmail_WithEmptyString_SetsEmptyEmail()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.ChangeEmail("");

        // Assert
        Assert.AreEqual("", user.Email);
    }

    #endregion

    #region Gamification Methods Tests

    [TestMethod]
    [TestCategory("Gamification")]
    public void AddPoints_IncreasesTotalPoints()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");
        int initialPoints = user.TotalPoints;

        // Act
        user.AddPoints(10);

        // Assert
        Assert.AreEqual(initialPoints + 10, user.TotalPoints);
    }

    [TestMethod]
    [TestCategory("Gamification")]
    public void AddPoints_MultipleTimes_AccumulatesCorrectly()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.AddPoints(10);
        user.AddPoints(20);
        user.AddPoints(30);

        // Assert
        Assert.AreEqual(60, user.TotalPoints);
    }

    [TestMethod]
    [TestCategory("Gamification")]
    public void AddPoints_WithNegativePoints_DecreasesTotal()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");
        user.AddPoints(100);

        // Act
        user.AddPoints(-10);

        // Assert
        Assert.AreEqual(90, user.TotalPoints);
    }

    [TestMethod]
    [TestCategory("Gamification")]
    public void UpdateStreak_SetsNewStreak()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.UpdateStreak(5);

        // Assert
        Assert.AreEqual(5, user.Streak);
    }

    [TestMethod]
    [TestCategory("Gamification")]
    public void UpdateStreak_WithZero_ResetsStreak()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");
        user.UpdateStreak(10);

        // Act
        user.UpdateStreak(0);

        // Assert
        Assert.AreEqual(0, user.Streak);
    }

    [TestMethod]
    [TestCategory("Gamification")]
    public void UpdateLevel_SetsNewLevel()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.UpdateLevel("B1");

        // Assert
        Assert.AreEqual("B1", user.CurrentLevel);
    }

    [TestMethod]
    [TestCategory("Gamification")]
    public void UpdateLevel_ToHigherLevel_UpdatesCorrectly()
    {
        // Arrange
        var user = User.Create("testuser", "test@example.com", "hash");

        // Act
        user.UpdateLevel("A2");
        user.UpdateLevel("B1");
        user.UpdateLevel("C1");

        // Assert
        Assert.AreEqual("C1", user.CurrentLevel);
    }

    #endregion

    #region Property Tests

    [TestMethod]
    [TestCategory("Property")]
    public void Id_HasDefaultValueOfZero()
    {
        // Arrange & Act
        var user = User.Create("testuser", "test@example.com", "hash");

        // Assert
        Assert.AreEqual(0, user.Id);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void Username_HasPrivateSetter()
    {
        // Arrange
        var username = "testuser";

        // Act
        var user = User.Create(username, "test@example.com", "hash");

        // Assert
        Assert.AreEqual(username, user.Username);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void Email_HasPrivateSetter()
    {
        // Arrange
        var email = "test@example.com";

        // Act
        var user = User.Create("testuser", email, "hash");

        // Assert
        Assert.AreEqual(email, user.Email);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void PasswordHash_HasPrivateSetter()
    {
        // Arrange
        var passwordHash = "hashed-password-123";

        // Act
        var user = User.Create("testuser", "test@example.com", passwordHash);

        // Assert
        Assert.AreEqual(passwordHash, user.PasswordHash);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void CurrentLevel_HasDefaultValueOf_A1()
    {
        // Arrange & Act
        var user = User.Create("testuser", "test@example.com", "hash");

        // Assert
        Assert.AreEqual("A1", user.CurrentLevel);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void Streak_HasDefaultValueOfZero()
    {
        // Arrange & Act
        var user = User.Create("testuser", "test@example.com", "hash");

        // Assert
        Assert.AreEqual(0, user.Streak);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void TotalPoints_HasDefaultValueOfZero()
    {
        // Arrange & Act
        var user = User.Create("testuser", "test@example.com", "hash");

        // Assert
        Assert.AreEqual(0, user.TotalPoints);
    }

    [TestMethod]
    [TestCategory("Property")]
    public void CreatedAt_IsSetToCurrentTime()
    {
        // Arrange
        var beforeCreation = DateTime.UtcNow;

        // Act
        var user = User.Create("testuser", "test@example.com", "hash");
        var afterCreation = DateTime.UtcNow;

        // Assert
        Assert.IsTrue(user.CreatedAt >= beforeCreation);
        Assert.IsTrue(user.CreatedAt <= afterCreation);
    }

    #endregion
}