DocumentService/DocumentService.Tests/Unit/Application/Features/ConvertPdfA/ConvertPdfAHandlerTests.cs

using DocumentService.Application.Common.Interfaces;
using DocumentService.Application.ConvertToPdfA;
using DocumentService.Application.ConvertFromPdfA;
using DocumentService.Domain.Common.Exceptions;
using FluentAssertions;
using Moq;
using Xunit;

namespace DocumentService.Tests.Unit.Application.Features.ConvertPdfA;

public class ConvertToPdfAHandlerTests
{
    private readonly Mock<IPdfProcessor> _mockProcessor;
    private readonly ConvertToPdfACommandHandler _handler;
    private static readonly byte[] FakePdfBytes = "%PDF"u8.ToArray();

    public ConvertToPdfAHandlerTests()
    {
        _mockProcessor = new Mock<IPdfProcessor>();
        _handler = new ConvertToPdfACommandHandler(_mockProcessor.Object);
    }

    [Fact]
    public async Task Handle_ValidPdfAndLevel_ReturnsConvertedBytes()
    {
        // Arrange
        var command = new ConvertToPdfACommand { PdfStream = new MemoryStream(FakePdfBytes), PdfALevel = "PDF/A-3b" };
        var expected = new byte[] { 0x25, 0x50, 0x44, 0x46, 0x0A };
        _mockProcessor.Setup(x => x.ConvertToPdfAAsync(It.IsAny<Stream>(), "PDF/A-3b")).ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(command, CancellationToken.None);

        // Assert
        result.Should().BeEquivalentTo(expected);
        _mockProcessor.Verify(x => x.ConvertToPdfAAsync(It.IsAny<Stream>(), "PDF/A-3b"), Times.Once);
    }

    [Fact]
    public async Task Handle_ProcessorThrowsNotImplemented_PropagatesException()
    {
        // Arrange
        var command = new ConvertToPdfACommand { PdfStream = new MemoryStream(FakePdfBytes), PdfALevel = "PDF/A-1b" };
        _mockProcessor.Setup(x => x.ConvertToPdfAAsync(It.IsAny<Stream>(), "PDF/A-1b"))
            .ThrowsAsync(new NotImplementedException("PDF/A conversion not yet implemented"));

        // Act & Assert
        var ex = await Assert.ThrowsAsync<NotImplementedException>(
            () => _handler.Handle(command, CancellationToken.None));
        ex.Message.Should().Contain("not yet implemented");
    }

    [Fact]
    public async Task Handle_ProcessorThrowsBadRequest_PropagatesException()
    {
        // Arrange
        var command = new ConvertToPdfACommand { PdfStream = new MemoryStream(FakePdfBytes), PdfALevel = "PDF/A-2b" };
        _mockProcessor.Setup(x => x.ConvertToPdfAAsync(It.IsAny<Stream>(), "PDF/A-2b"))
            .ThrowsAsync(new BadRequestException("PDF stream cannot be empty"));

        // Act & Assert
        var ex = await Assert.ThrowsAsync<BadRequestException>(
            () => _handler.Handle(command, CancellationToken.None));
        ex.Message.Should().Contain("empty");
    }
}

public class ConvertFromPdfAHandlerTests
{
    private readonly Mock<IPdfProcessor> _mockProcessor;
    private readonly ConvertFromPdfACommandHandler _handler;
    private static readonly byte[] FakePdfBytes = "%PDF"u8.ToArray();

    public ConvertFromPdfAHandlerTests()
    {
        _mockProcessor = new Mock<IPdfProcessor>();
        _handler = new ConvertFromPdfACommandHandler(_mockProcessor.Object);
    }

    [Fact]
    public async Task Handle_ValidPdfA_ReturnsStandardPdfBytes()
    {
        // Arrange
        var command = new ConvertFromPdfACommand { PdfStream = new MemoryStream(FakePdfBytes) };
        var expected = new byte[] { 0x25, 0x50, 0x44, 0x46, 0x0B };
        _mockProcessor.Setup(x => x.ConvertFromPdfAAsync(It.IsAny<Stream>())).ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(command, CancellationToken.None);

        // Assert
        result.Should().BeEquivalentTo(expected);
        _mockProcessor.Verify(x => x.ConvertFromPdfAAsync(It.IsAny<Stream>()), Times.Once);
    }

    [Fact]
    public async Task Handle_ProcessorThrowsBadRequest_PropagatesException()
    {
        // Arrange
        var command = new ConvertFromPdfACommand { PdfStream = new MemoryStream(FakePdfBytes) };
        _mockProcessor.Setup(x => x.ConvertFromPdfAAsync(It.IsAny<Stream>()))
            .ThrowsAsync(new BadRequestException("PDF stream must be at position 0"));

        // Act & Assert
        var ex = await Assert.ThrowsAsync<BadRequestException>(
            () => _handler.Handle(command, CancellationToken.None));
        ex.Message.Should().Contain("position 0");
    }

    [Fact]
    public async Task Handle_ProcessorThrowsGenericException_PropagatesException()
    {
        // Arrange
        var command = new ConvertFromPdfACommand { PdfStream = new MemoryStream(FakePdfBytes) };
        _mockProcessor.Setup(x => x.ConvertFromPdfAAsync(It.IsAny<Stream>()))
            .ThrowsAsync(new Exception("Unexpected error"));

        // Act & Assert
        await Assert.ThrowsAsync<Exception>(() => _handler.Handle(command, CancellationToken.None));
    }
}