prefab-page-detail/Prefab.Tests/Unit/Web/Shared/ExceptionHandlerShould.cs

using FluentValidation;
using FluentValidation.Results;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Json;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using Microsoft.EntityFrameworkCore;
using Prefab.Handler;
using Prefab.Catalog.Domain.Exceptions;
using Prefab.Web.Shared;
using Shouldly;
using System.Text.Json;

namespace Prefab.Tests.Unit.Web.Shared;

public sealed class ExceptionHandlerShould
{
    [Fact]
    public async Task ReturnBadRequestForValidationFailures()
    {
        var failure = new ValidationFailure("productId", "Either productId or sku must be provided.");
        var exception = new ValidationException(new[] { failure });

        var context = new DefaultHttpContext();
        context.Response.Body = new MemoryStream();

        var services = new ServiceCollection();
        services.AddSingleton<IHandlerContextAccessor, HandlerContextAccessor>();
        using var provider = services.BuildServiceProvider();
        context.RequestServices = provider;

        var middleware = new ExceptionHandler(
            _ => throw exception,
            NullLogger<ExceptionHandler>.Instance,
            Options.Create(new JsonOptions()));

        await middleware.InvokeAsync(context);

        context.Response.StatusCode.ShouldBe(StatusCodes.Status400BadRequest);

        context.Response.Body.Seek(0, SeekOrigin.Begin);
        using var reader = new StreamReader(context.Response.Body);
        var payload = await reader.ReadToEndAsync(TestContext.Current.CancellationToken);

        using var document = JsonDocument.Parse(payload);
        var root = document.RootElement;

        var messages = new List<string>();
        if (root.TryGetProperty("errors", out var errorsElement))
        {
            messages.AddRange(
                errorsElement
                    .EnumerateObject()
                    .SelectMany(property => property.Value.EnumerateArray())
                    .Select(element => element.GetString())
                    .Where(message => !string.IsNullOrWhiteSpace(message))!
                    .Cast<string>());
        }

        if (messages.Count == 0 && root.TryGetProperty("detail", out var detailElement))
        {
            messages.Add(detailElement.GetString() ?? string.Empty);
        }

        messages.ShouldNotBeEmpty(payload);
        messages.ShouldContain(message => message.Equals("Either productId or sku must be provided.", StringComparison.OrdinalIgnoreCase));
    }

    [Fact]
    public async Task ReturnBadRequestForDomainExceptions()
    {
        var exception = new DomainValidationException("Demo domain failure.");

        var context = new DefaultHttpContext();
        context.Response.Body = new MemoryStream();

        var services = new ServiceCollection();
        services.AddSingleton<IHandlerContextAccessor, HandlerContextAccessor>();
        using var provider = services.BuildServiceProvider();
        context.RequestServices = provider;

        var middleware = new ExceptionHandler(
            _ => throw exception,
            NullLogger<ExceptionHandler>.Instance,
            Options.Create(new JsonOptions()));

        await middleware.InvokeAsync(context);

        context.Response.StatusCode.ShouldBe(StatusCodes.Status400BadRequest);
        context.Response.Body.Seek(0, SeekOrigin.Begin);
        using var reader = new StreamReader(context.Response.Body);
        var payload = await reader.ReadToEndAsync(TestContext.Current.CancellationToken);

        using var document = JsonDocument.Parse(payload);
        var detail = document.RootElement.GetProperty("detail").GetString();
        document.RootElement.GetProperty("type").GetString().ShouldBe("https://prefab.dev/problems/domain-error");
        detail.ShouldNotBeNull();
        detail!.ShouldContain("Demo domain failure.");
    }

    [Fact]
    public async Task ReturnConflictForConcurrencyExceptions()
    {
        var exception = new DbUpdateConcurrencyException("Concurrency conflict");

        var context = new DefaultHttpContext();
        context.Response.Body = new MemoryStream();

        var services = new ServiceCollection();
        services.AddSingleton<IHandlerContextAccessor, HandlerContextAccessor>();
        using var provider = services.BuildServiceProvider();
        context.RequestServices = provider;

        var middleware = new ExceptionHandler(
            _ => throw exception,
            NullLogger<ExceptionHandler>.Instance,
            Options.Create(new JsonOptions()));

        await middleware.InvokeAsync(context);

        context.Response.StatusCode.ShouldBe(StatusCodes.Status409Conflict);
        context.Response.Body.Seek(0, SeekOrigin.Begin);
        using var reader = new StreamReader(context.Response.Body);
        var payload = await reader.ReadToEndAsync(TestContext.Current.CancellationToken);

        using var document = JsonDocument.Parse(payload);
        document.RootElement.GetProperty("type").GetString().ShouldBe("https://prefab.dev/problems/concurrency-conflict");
    }

}