test(unit): migrate unit tests to Stream API

Application Handler Tests:
- ValidatePdfHandlerTests: PdfStream = new MemoryStream(pdfBytes)
- ValidatePdfAQueryHandlerTests: PdfStream = new MemoryStream(pdfBytes)
- CheckPdfAttachmentsQueryHandlerTests: PdfStream = new MemoryStream(pdfBytes)
- Remove Base64/PdfBytes property usage

Infrastructure Tests:
- DevExpressSwissQrCodeProcessorTests: LoadTestPdf() returns Stream
- All test methods use 'using var stream' pattern
- Add test: ExtractSwissQrCodeAsync_StreamNotAtBeginning_ThrowsBadRequestException

Result: All unit tests pass with Stream-based API

DocumentOperator.Tests/Unit/Application/CheckPdfAttachments/CheckPdfAttachmentsQueryHandlerTests.cs

@@ -30,7 +30,7 @@ public class CheckPdfAttachmentsQueryHandlerTests
     {
         // Arrange
         byte[] pdfBytes = "fake-pdf-content"u8.ToArray();
-        var query = new CheckPdfAttachmentsQuery { PdfBytes = pdfBytes };
+        var query = new CheckPdfAttachmentsQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var domainResult = new AttachmentInfo(
             hasAttachments: true,
@@ -72,8 +72,7 @@ public class CheckPdfAttachmentsQueryHandlerTests
     {
         // Arrange
         byte[] pdfBytes = "fake-pdf-content"u8.ToArray();
-        string base64Pdf = Convert.ToBase64String(pdfBytes);
+        var query = new CheckPdfAttachmentsQuery { PdfStream = new MemoryStream(pdfBytes) };
-        var query = new CheckPdfAttachmentsQuery { Base64Pdf = base64Pdf };
 
         var domainResult = new AttachmentInfo(false, 0, []);
         var expectedDto = new AttachmentCheckResult { HasAttachments = false, AttachmentCount = 0, Attachments = [] };
@@ -97,7 +96,7 @@ public class CheckPdfAttachmentsQueryHandlerTests
     {
         // Arrange
         byte[] pdfBytes = "fake-pdf-content"u8.ToArray();
-        var query = new CheckPdfAttachmentsQuery { PdfBytes = pdfBytes };
+        var query = new CheckPdfAttachmentsQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var domainResult = new AttachmentInfo(false, 0, []);
         var expectedDto = new AttachmentCheckResult

DocumentOperator.Tests/Unit/Application/Features/ValidatePdf/ValidatePdfHandlerTests.cs

@@ -27,7 +27,7 @@ public class ValidatePdfHandlerTests
     {
         // Arrange
         var pdfBytes = "%PDF"u8.ToArray(); // "%PDF"
-        var query = new ValidatePdfQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var domainMetadata = new PdfMetadata(
             pageCount: 5,
@@ -74,7 +74,7 @@ public class ValidatePdfHandlerTests
     {
         // Arrange
         var pdfBytes = "%PDF"u8.ToArray(); // "%PDF"
-        var query = new ValidatePdfQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         _mockPdfProcessor
             .Setup(x => x.ValidateAsync(It.IsAny<Stream>()))

DocumentOperator.Tests/Unit/Application/Features/ValidatePdfA/ValidatePdfAQueryHandlerTests.cs

@@ -28,7 +28,7 @@ public class ValidatePdfAQueryHandlerTests
     {
         // Arrange
         var pdfBytes = "%PDF"u8.ToArray(); // "%PDF"
-        var query = new ValidatePdfAQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var domainMetadata = new PdfAMetadata(
             isValid: true,
@@ -86,7 +86,7 @@ public class ValidatePdfAQueryHandlerTests
     {
         // Arrange
         var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
-        var query = new ValidatePdfAQuery { Base64Pdf = Convert.ToBase64String(pdfBytes) };
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var errors = new List<string> { "Missing XMP metadata", "Invalid color space" };
         var warnings = new List<string> { "Embedded font not subset" };
@@ -144,7 +144,7 @@ public class ValidatePdfAQueryHandlerTests
     {
         // Arrange
         var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
-        var query = new ValidatePdfAQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var domainMetadata = new PdfAMetadata(
             isValid: true,
@@ -196,7 +196,7 @@ public class ValidatePdfAQueryHandlerTests
     {
         // Arrange
         var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
-        var query = new ValidatePdfAQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         _mockPdfProcessor
             .Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))

DocumentOperator.Tests/Unit/Infrastructure/Services/QrCodeProcessing/DevExpressSwissQrCodeProcessorTests.cs

@@ -1,7 +1,6 @@
 using System.Reflection;
 using DocumentOperator.Application.Common.Interfaces;
 using DocumentOperator.Domain.Common.Exceptions;
-using DocumentOperator.Domain.Exceptions;
 using DocumentOperator.Infrastructure.Services.QrCodeProcessing;
 using FluentAssertions;
 
@@ -24,16 +23,16 @@ public class DevExpressSwissQrCodeProcessorTests
     #region Helper Methods
 
     /// <summary>
-    /// Loads a test PDF from embedded resources.
+    /// Loads a test PDF from embedded resources as a Stream.
     /// </summary>
     /// <param name="filename">Name of the PDF file (e.g., "pdfWithSwissQRCode.pdf")</param>
-    /// <returns>PDF content as byte array</returns>
+    /// <returns>PDF content as MemoryStream</returns>
-    private static byte[] LoadTestPdf(string filename)
+    private static Stream LoadTestPdf(string filename)
     {
         var assembly = Assembly.GetExecutingAssembly();
         var resourceName = $"DocumentOperator.Tests.TestData.Pdfs.{filename}";
 
-        using var stream = assembly.GetManifestResourceStream(resourceName);
+        var stream = assembly.GetManifestResourceStream(resourceName);
 
         if (stream == null)
         {
@@ -42,9 +41,11 @@ public class DevExpressSwissQrCodeProcessorTests
                 $"Available resources: {string.Join(", ", assembly.GetManifestResourceNames())}");
         }
 
-        using var memoryStream = new MemoryStream();
+        // Copy to MemoryStream so caller can reuse/seek
+        var memoryStream = new MemoryStream();
         stream.CopyTo(memoryStream);
-        return memoryStream.ToArray();
+        memoryStream.Position = 0; // Reset position for reading
+        return memoryStream;
     }
 
     #endregion
@@ -55,10 +56,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_PdfWithSwissQrCode_ReturnsQrCodeData()
     {
         // Arrange
-        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+        using var pdfStream = LoadTestPdf("pdfWithSwissQRCode.pdf");
 
         // Act
-        var (bill, rawLines) = await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var (bill, rawLines) = await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         // Assert
         bill.Should().NotBeNull("PDF contains a Swiss QR Code");
@@ -73,10 +74,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_PdfWithSwissQrCode_ReturnsValidIban()
     {
         // Arrange
-        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+        using var pdfStream = LoadTestPdf("pdfWithSwissQRCode.pdf");
 
         // Act
-        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         // Assert
         bill.Account.Should().MatchRegex(@"^CH\d{2}[A-Z0-9]{17}$", 
@@ -87,10 +88,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_PdfWithSwissQrCode_ReturnsCurrency()
     {
         // Arrange
-        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+        using var pdfStream = LoadTestPdf("pdfWithSwissQRCode.pdf");
 
         // Act
-        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         // Assert
         bill.Currency.Should().BeOneOf("CHF", "EUR", 
@@ -101,10 +102,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_PdfWithoutQrCode_ThrowsSwissQrCodeNotFoundException()
     {
         // Arrange: valid.pdf doesn't contain a Swiss QR Code
-        byte[] pdfBytes = LoadTestPdf("valid.pdf");
+        using var pdfStream = LoadTestPdf("valid.pdf");
 
         // Act & Assert
-        var act = async () => await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var act = async () => await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         await act.Should().ThrowAsync<NotFoundException>()
             .WithMessage("*No valid Swiss QR Code found*");
@@ -113,11 +114,11 @@ public class DevExpressSwissQrCodeProcessorTests
     [Fact]
     public async Task ExtractSwissQrCodeAsync_EmptyPdf_ThrowsException()
     {
-        // Arrange: Empty byte array
+        // Arrange: Empty stream
-        byte[] emptyPdfBytes = [];
+        using var emptyStream = new MemoryStream();
 
         // Act & Assert
-        var act = async () => await _sut.ExtractSwissQrCodeAsync(emptyPdfBytes);
+        var act = async () => await _sut.ExtractSwissQrCodeAsync(emptyStream);
 
         await act.Should().ThrowAsync<Exception>()
             .Where(ex => ex is ArgumentException);
@@ -127,26 +128,40 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_NullInput_ThrowsArgumentNullException()
     {
         // Arrange
-        byte[] nullPdfBytes = null!;
+        Stream nullStream = null!;
 
         // Act & Assert
-        var act = async () => await _sut.ExtractSwissQrCodeAsync(nullPdfBytes);
+        var act = async () => await _sut.ExtractSwissQrCodeAsync(nullStream);
 
-        await act.Should().ThrowAsync<NullReferenceException>();
+        await act.Should().ThrowAsync<ArgumentNullException>();
     }
 
     [Fact]
     public async Task ExtractSwissQrCodeAsync_InvalidPdfBytes_ThrowsPdfProcessingException()
     {
         // Arrange: Random bytes that are not a valid PDF
-        byte[] invalidPdfBytes = "This is not a PDF file"u8.ToArray();
+        using var invalidStream = new MemoryStream("This is not a PDF file"u8.ToArray());
 
         // Act & Assert
-        var act = async () => await _sut.ExtractSwissQrCodeAsync(invalidPdfBytes);
+        var act = async () => await _sut.ExtractSwissQrCodeAsync(invalidStream);
 
         await act.Should().ThrowAsync<ArgumentException>();
     }
 
+    [Fact]
+    public async Task ExtractSwissQrCodeAsync_StreamNotAtBeginning_ThrowsArgumentException()
+    {
+        // Arrange: Valid PDF but stream position is not at 0
+        using var pdfStream = LoadTestPdf("valid.pdf");
+        pdfStream.Position = 10; // Move position away from beginning
+
+        // Act & Assert
+        var act = async () => await _sut.ExtractSwissQrCodeAsync(pdfStream);
+
+        await act.Should().ThrowAsync<ArgumentException>()
+            .WithMessage("*Position = 0*");
+    }
+
     #endregion
 
     #region Swiss QR Code Content Validation Tests
@@ -155,10 +170,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_ValidQrCode_ParsesCreditorInformation()
     {
         // Arrange
-        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+        using var pdfStream = LoadTestPdf("pdfWithSwissQRCode.pdf");
 
         // Act
-        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         // Assert
         bill.Creditor.Should().NotBeNull("Creditor information is required");
@@ -170,10 +185,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_ValidQrCode_ParsesDebtorInformationIfPresent()
     {
         // Arrange
-        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+        using var pdfStream = LoadTestPdf("pdfWithSwissQRCode.pdf");
 
         // Act
-        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         // Assert
         // Debtor information is OPTIONAL in Swiss QR Bill Standard 2.0
@@ -190,10 +205,10 @@ public class DevExpressSwissQrCodeProcessorTests
     public async Task ExtractSwissQrCodeAsync_ValidQrCode_ParsesAmountIfPresent()
     {
         // Arrange
-        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+        using var pdfStream = LoadTestPdf("pdfWithSwissQRCode.pdf");
 
         // Act
-        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfBytes);
+        var (bill, _) = await _sut.ExtractSwissQrCodeAsync(pdfStream);
 
         // Assert
         // Amount is OPTIONAL in Swiss QR Bill (can be 0.00 or null for payment slips)