ChatBot/ChatBot.Tests/Services/DatabaseInitializationServiceExceptionTests.cs

using ChatBot.Data;
using ChatBot.Services;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Moq;

namespace ChatBot.Tests.Services;

public class DatabaseInitializationServiceExceptionTests
{
    [Fact]
    public async Task StartAsync_WhenDatabaseDoesNotExist_ShouldRetryWithMigration()
    {
        // Arrange
        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
        
        // Ensure database does not exist
        if (File.Exists(dbPath))
        {
            File.Delete(dbPath);
        }

        var services = new ServiceCollection();
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}")
                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
        );

        var serviceProvider = services.BuildServiceProvider();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);

        try
        {
            // Act
            await service.StartAsync(CancellationToken.None);

            // Assert - database should be created
            File.Exists(dbPath).Should().BeTrue();

            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>(
                            (v, t) =>
                                v.ToString()!.Contains("Database initialization completed successfully")
                        ),
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.Once
            );
        }
        finally
        {
            // Cleanup
            serviceProvider.Dispose();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (File.Exists(dbPath))
            {
                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
            }
        }
    }

    [Fact]
    public async Task StartAsync_WhenCanConnectThrowsSpecificException_ShouldHandleGracefully()
    {
        // Arrange
        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
        var services = new ServiceCollection();
        
        // Use SQLite with a valid connection string
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}")
                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
        );

        var serviceProvider = services.BuildServiceProvider();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);

        try
        {
            // Act
            await service.StartAsync(CancellationToken.None);

            // Assert - should complete successfully even if database didn't exist initially
            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>(
                            (v, t) =>
                                v.ToString()!.Contains("Database initialization completed successfully")
                        ),
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.Once
            );
        }
        finally
        {
            // Cleanup
            serviceProvider.Dispose();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (File.Exists(dbPath))
            {
                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
            }
        }
    }

    [Fact]
    public async Task StartAsync_WithCanceledToken_ShouldThrowOperationCanceledException()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var cts = new CancellationTokenSource();
        cts.Cancel(); // Cancel before starting

        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(cts.Token);
        await act.Should().ThrowAsync<InvalidOperationException>();
    }
}