Deal/src/core/tests/Deal.Tests.Unit/Api/DealExceptionHandlerTests.cs

using System.Text.Json;
using Deal.Api.Middleware;
using Deal.SharedKernel.Errors;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using NSubstitute;

namespace Deal.Tests.Unit.Api;

/// <summary>
/// Тесты обработчика необработанных исключений HTTP.
/// </summary>
public sealed class DealExceptionHandlerTests
{
    [Fact]
    public async Task NotFound_MapsTo404WithCodeAndRussianDetail()
    {
        DefaultHttpContext context = CreateContext();
        DealExceptionHandler handler = new(Substitute.For<ILogger<DealExceptionHandler>>());

        bool handled = await handler.TryHandleAsync(
            context,
            new NotFoundException("Карточка", "c_1"),
            CancellationToken.None);

        Assert.True(handled);
        Assert.Equal(StatusCodes.Status404NotFound, context.Response.StatusCode);
        (string detail, string code) = await ReadBodyAsync(context);
        Assert.Equal(DealErrorCodes.NotFound, code);
        Assert.Contains("Карточка", detail);
    }

    [Fact]
    public async Task Unavailable_MapsTo503()
    {
        DefaultHttpContext context = CreateContext();
        DealExceptionHandler handler = new(Substitute.For<ILogger<DealExceptionHandler>>());

        await handler.TryHandleAsync(
            context,
            new ServiceUnavailableException("ИИ"),
            CancellationToken.None);

        Assert.Equal(StatusCodes.Status503ServiceUnavailable, context.Response.StatusCode);
    }

    [Fact]
    public async Task UnexpectedException_MapsToGeneric500WithoutStackOrDetails()
    {
        DefaultHttpContext context = CreateContext();
        DealExceptionHandler handler = new(Substitute.For<ILogger<DealExceptionHandler>>());

        bool handled = await handler.TryHandleAsync(
            context,
            new InvalidOperationException("секретная внутренняя деталь"),
            CancellationToken.None);

        Assert.True(handled);
        Assert.Equal(StatusCodes.Status500InternalServerError, context.Response.StatusCode);
        (string detail, string code) = await ReadBodyAsync(context);
        Assert.Equal(DealErrorCodes.Internal, code);
        Assert.DoesNotContain("секретная внутренняя деталь", detail);
        Assert.DoesNotContain("at ", detail);
    }

    private static DefaultHttpContext CreateContext()
    {
        var context = new DefaultHttpContext();
        context.Response.Body = new MemoryStream();
        return context;
    }

    private static async Task<(string Detail, string Code)> ReadBodyAsync(HttpContext context)
    {
        context.Response.Body.Seek(0, SeekOrigin.Begin);
        using var reader = new StreamReader(context.Response.Body);
        string json = await reader.ReadToEndAsync();
        using JsonDocument document = JsonDocument.Parse(json);
        return (
            document.RootElement.GetProperty("detail").GetString() ?? string.Empty,
            document.RootElement.GetProperty("code").GetString() ?? string.Empty);
    }
}