Musify/backend/Tests/Musify.Infrastructure.Tests/Services/PictureServiceTests.cs

using Microsoft.Extensions.Logging.Abstractions;
using Musify.Infrastructure.Services;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.PixelFormats;
using Xunit;

namespace Musify.Infrastructure.Tests.Services
{
    public sealed class PictureServiceTests
    {
        private static PictureService CreateService() => new(NullLogger<PictureService>.Instance);

        private static MemoryStream CreateSourceImage(int width, int height)
        {
            using var image = new Image<Rgba32>(width, height, new Rgba32(255, 0, 0));
            var stream = new MemoryStream();
            image.SaveAsPng(stream);
            stream.Position = 0;
            return stream;
        }

        [Fact]
        public async Task ResizePictureAsWebpAsync_LargerThanTarget_ShrinksToFitWithinTheRequestedBox()
        {
            using var source = CreateSourceImage(800, 600);

            await using var resized = await CreateService().ResizePictureAsWebpAsync(source, 200, 200, TestContext.Current.CancellationToken);

            using var result = await Image.LoadAsync(resized, TestContext.Current.CancellationToken);
            Assert.InRange(result.Width, 1, 200);
            Assert.InRange(result.Height, 1, 200);
            Assert.True(result.Width == 200 || result.Height == 200, "expected the longer side to land exactly on the target box");
        }

        [Fact]
        public async Task ResizePictureAsWebpAsync_ReturnsAValidWebpStream()
        {
            using var source = CreateSourceImage(100, 100);

            await using var resized = await CreateService().ResizePictureAsWebpAsync(source, 50, 50, TestContext.Current.CancellationToken);

            var format = await Image.DetectFormatAsync(resized, TestContext.Current.CancellationToken);
            Assert.Equal("WEBP", format?.Name, ignoreCase: true);
        }

        [Fact]
        public async Task ResizePictureAsWebpAsync_PreservesAspectRatio()
        {
            using var source = CreateSourceImage(400, 200);

            await using var resized = await CreateService().ResizePictureAsWebpAsync(source, 100, 100, TestContext.Current.CancellationToken);

            using var result = await Image.LoadAsync(resized, TestContext.Current.CancellationToken);
            Assert.Equal(100, result.Width);
            Assert.Equal(50, result.Height);
        }
    }
}