ChatBot/ChatBot.Tests/Models/ChatMessageEntityTests.cs

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Text.Json;
using ChatBot.Models.Entities;
using FluentAssertions;

namespace ChatBot.Tests.Models;

public class ChatMessageEntityTests
{
    [Fact]
    public void Constructor_ShouldInitializePropertiesWithDefaultValues()
    {
        // Arrange & Act
        var entity = new ChatMessageEntity();

        // Assert
        entity.Id.Should().Be(0);
        entity.SessionId.Should().Be(0);
        entity.Content.Should().Be(string.Empty);
        entity.Role.Should().Be(string.Empty);
        entity.CreatedAt.Should().BeCloseTo(DateTime.UtcNow, TimeSpan.FromSeconds(1));
        entity.MessageOrder.Should().Be(0);
        entity.Session.Should().BeNull();
    }

    [Fact]
    public void Id_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedId = 123;

        // Act
        entity.Id = expectedId;

        // Assert
        entity.Id.Should().Be(expectedId);
    }

    [Fact]
    public void SessionId_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedSessionId = 456;

        // Act
        entity.SessionId = expectedSessionId;

        // Assert
        entity.SessionId.Should().Be(expectedSessionId);
    }

    [Fact]
    public void Content_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedContent = "Hello, world!";

        // Act
        entity.Content = expectedContent;

        // Assert
        entity.Content.Should().Be(expectedContent);
    }

    [Fact]
    public void Role_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedRole = "user";

        // Act
        entity.Role = expectedRole;

        // Assert
        entity.Role.Should().Be(expectedRole);
    }

    [Fact]
    public void CreatedAt_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedDate = DateTime.UtcNow.AddDays(-1);

        // Act
        entity.CreatedAt = expectedDate;

        // Assert
        entity.CreatedAt.Should().Be(expectedDate);
    }

    [Fact]
    public void MessageOrder_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedOrder = 5;

        // Act
        entity.MessageOrder = expectedOrder;

        // Assert
        entity.MessageOrder.Should().Be(expectedOrder);
    }

    [Fact]
    public void Session_ShouldBeSettable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var expectedSession = new ChatSessionEntity();

        // Act
        entity.Session = expectedSession;

        // Assert
        entity.Session.Should().Be(expectedSession);
    }

    [Theory]
    [InlineData("user")]
    [InlineData("assistant")]
    [InlineData("system")]
    [InlineData("function")]
    public void Role_ShouldAcceptValidRoles(string role)
    {
        // Arrange
        var entity = new ChatMessageEntity();

        // Act
        entity.Role = role;

        // Assert
        entity.Role.Should().Be(role);
    }

    [Theory]
    [InlineData("")]
    [InlineData("a")]
    [InlineData("very long role name that exceeds limit")]
    public void Role_ShouldAcceptVariousLengths(string role)
    {
        // Arrange
        var entity = new ChatMessageEntity();

        // Act
        entity.Role = role;

        // Assert
        entity.Role.Should().Be(role);
        entity.Role.Length.Should().Be(role.Length);
    }

    [Theory]
    [InlineData("")]
    [InlineData("Short message")]
    [InlineData(
        "A very long message that contains a lot of text and should still be valid for the content field"
    )]
    public void Content_ShouldAcceptVariousLengths(string content)
    {
        // Arrange
        var entity = new ChatMessageEntity();

        // Act
        entity.Content = content;

        // Assert
        entity.Content.Should().Be(content);
    }

    [Fact]
    public void CreatedAt_ShouldDefaultToCurrentUtcTime()
    {
        // Arrange
        var beforeCreation = DateTime.UtcNow;

        // Act
        var entity = new ChatMessageEntity();

        // Assert
        entity.CreatedAt.Should().BeOnOrAfter(beforeCreation);
        entity.CreatedAt.Should().BeOnOrBefore(DateTime.UtcNow);
    }

    [Fact]
    public void AllProperties_ShouldBeMutable()
    {
        // Arrange
        var entity = new ChatMessageEntity();
        var session = new ChatSessionEntity();

        // Act
        entity.Id = 1;
        entity.SessionId = 2;
        entity.Content = "Test content";
        entity.Role = "user";
        entity.CreatedAt = DateTime.UtcNow.AddDays(-1);
        entity.MessageOrder = 3;
        entity.Session = session;

        // Assert
        entity.Id.Should().Be(1);
        entity.SessionId.Should().Be(2);
        entity.Content.Should().Be("Test content");
        entity.Role.Should().Be("user");
        entity.CreatedAt.Should().BeCloseTo(DateTime.UtcNow.AddDays(-1), TimeSpan.FromSeconds(1));
        entity.MessageOrder.Should().Be(3);
        entity.Session.Should().Be(session);
    }

    [Fact]
    public void Entity_ShouldHaveCorrectTableAttribute()
    {
        // Arrange
        var entityType = typeof(ChatMessageEntity);
        var tableAttribute =
            entityType.GetCustomAttributes(typeof(TableAttribute), false).FirstOrDefault()
            as TableAttribute;

        // Assert
        tableAttribute.Should().NotBeNull();
        tableAttribute!.Name.Should().Be("chat_messages");
    }

    [Fact]
    public void Id_ShouldHaveKeyAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Id));
        var keyAttribute =
            property?.GetCustomAttributes(typeof(KeyAttribute), false).FirstOrDefault()
            as KeyAttribute;

        // Assert
        keyAttribute.Should().NotBeNull();
    }

    [Fact]
    public void Id_ShouldHaveColumnAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Id));
        var columnAttribute =
            property?.GetCustomAttributes(typeof(ColumnAttribute), false).FirstOrDefault()
            as ColumnAttribute;

        // Assert
        columnAttribute.Should().NotBeNull();
        columnAttribute!.Name.Should().Be("id");
    }

    [Fact]
    public void SessionId_ShouldHaveRequiredAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.SessionId));
        var requiredAttribute =
            property?.GetCustomAttributes(typeof(RequiredAttribute), false).FirstOrDefault()
            as RequiredAttribute;

        // Assert
        requiredAttribute.Should().NotBeNull();
    }

    [Fact]
    public void SessionId_ShouldHaveColumnAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.SessionId));
        var columnAttribute =
            property?.GetCustomAttributes(typeof(ColumnAttribute), false).FirstOrDefault()
            as ColumnAttribute;

        // Assert
        columnAttribute.Should().NotBeNull();
        columnAttribute!.Name.Should().Be("session_id");
    }

    [Fact]
    public void Content_ShouldHaveRequiredAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Content));
        var requiredAttribute =
            property?.GetCustomAttributes(typeof(RequiredAttribute), false).FirstOrDefault()
            as RequiredAttribute;

        // Assert
        requiredAttribute.Should().NotBeNull();
    }

    [Fact]
    public void Content_ShouldHaveStringLengthAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Content));
        var stringLengthAttribute =
            property?.GetCustomAttributes(typeof(StringLengthAttribute), false).FirstOrDefault()
            as StringLengthAttribute;

        // Assert
        stringLengthAttribute.Should().NotBeNull();
        stringLengthAttribute!.MaximumLength.Should().Be(10000);
    }

    [Fact]
    public void Content_ShouldHaveColumnAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Content));
        var columnAttribute =
            property?.GetCustomAttributes(typeof(ColumnAttribute), false).FirstOrDefault()
            as ColumnAttribute;

        // Assert
        columnAttribute.Should().NotBeNull();
        columnAttribute!.Name.Should().Be("content");
    }

    [Fact]
    public void Role_ShouldHaveRequiredAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Role));
        var requiredAttribute =
            property?.GetCustomAttributes(typeof(RequiredAttribute), false).FirstOrDefault()
            as RequiredAttribute;

        // Assert
        requiredAttribute.Should().NotBeNull();
    }

    [Fact]
    public void Role_ShouldHaveStringLengthAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Role));
        var stringLengthAttribute =
            property?.GetCustomAttributes(typeof(StringLengthAttribute), false).FirstOrDefault()
            as StringLengthAttribute;

        // Assert
        stringLengthAttribute.Should().NotBeNull();
        stringLengthAttribute!.MaximumLength.Should().Be(20);
    }

    [Fact]
    public void Role_ShouldHaveColumnAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Role));
        var columnAttribute =
            property?.GetCustomAttributes(typeof(ColumnAttribute), false).FirstOrDefault()
            as ColumnAttribute;

        // Assert
        columnAttribute.Should().NotBeNull();
        columnAttribute!.Name.Should().Be("role");
    }

    [Fact]
    public void CreatedAt_ShouldHaveRequiredAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.CreatedAt));
        var requiredAttribute =
            property?.GetCustomAttributes(typeof(RequiredAttribute), false).FirstOrDefault()
            as RequiredAttribute;

        // Assert
        requiredAttribute.Should().NotBeNull();
    }

    [Fact]
    public void CreatedAt_ShouldHaveColumnAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.CreatedAt));
        var columnAttribute =
            property?.GetCustomAttributes(typeof(ColumnAttribute), false).FirstOrDefault()
            as ColumnAttribute;

        // Assert
        columnAttribute.Should().NotBeNull();
        columnAttribute!.Name.Should().Be("created_at");
    }

    [Fact]
    public void MessageOrder_ShouldHaveColumnAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(
            nameof(ChatMessageEntity.MessageOrder)
        );
        var columnAttribute =
            property?.GetCustomAttributes(typeof(ColumnAttribute), false).FirstOrDefault()
            as ColumnAttribute;

        // Assert
        columnAttribute.Should().NotBeNull();
        columnAttribute!.Name.Should().Be("message_order");
    }

    [Fact]
    public void Session_ShouldHaveForeignKeyAttribute()
    {
        // Arrange
        var property = typeof(ChatMessageEntity).GetProperty(nameof(ChatMessageEntity.Session));
        var foreignKeyAttribute =
            property?.GetCustomAttributes(typeof(ForeignKeyAttribute), false).FirstOrDefault()
            as ForeignKeyAttribute;

        // Assert
        foreignKeyAttribute.Should().NotBeNull();
        foreignKeyAttribute!.Name.Should().Be("SessionId");
    }

    [Fact]
    public void JsonSerialization_RoundTrip_ShouldPreserveScalarProperties()
    {
        // Arrange
        var original = new ChatMessageEntity
        {
            Id = 42,
            SessionId = 7,
            Content = "Hello JSON",
            Role = "user",
            CreatedAt = DateTime.UtcNow.AddMinutes(-5),
            MessageOrder = 3,
            Session = null!, // ensure navigation not required for serialization
        };

        var options = new JsonSerializerOptions
        {
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
            WriteIndented = false,
            DefaultIgnoreCondition = System
                .Text
                .Json
                .Serialization
                .JsonIgnoreCondition
                .WhenWritingNull,
        };

        // Act
        var json = JsonSerializer.Serialize(original, options);
        var deserialized = JsonSerializer.Deserialize<ChatMessageEntity>(json, options)!;

        // Assert
        deserialized.Id.Should().Be(original.Id);
        deserialized.SessionId.Should().Be(original.SessionId);
        deserialized.Content.Should().Be(original.Content);
        deserialized.Role.Should().Be(original.Role);
        deserialized.MessageOrder.Should().Be(original.MessageOrder);
        // Allow a small delta due to serialization precision
        deserialized.CreatedAt.Should().BeCloseTo(original.CreatedAt, TimeSpan.FromSeconds(1));
    }
}