diff --git a/DocumentOperator.Tests/Unit/Infrastructure/Services/PdfProcessing/DevExpressPdfProcessorTests.cs b/DocumentOperator.Tests/Unit/Infrastructure/Services/PdfProcessing/DevExpressPdfProcessorTests.cs
index d5120f0..0e95294 100644
--- a/DocumentOperator.Tests/Unit/Infrastructure/Services/PdfProcessing/DevExpressPdfProcessorTests.cs
+++ b/DocumentOperator.Tests/Unit/Infrastructure/Services/PdfProcessing/DevExpressPdfProcessorTests.cs
@@ -1,7 +1,7 @@
-using System.Reflection;
+using System.Reflection;
+using DocumentOperator.Application.Common.DTOs;
 using DocumentOperator.Application.Common.Interfaces;
 using DocumentOperator.Domain.Common.Exceptions;
-using DocumentOperator.Domain.Models.ValueObjects;
 using DocumentOperator.Infrastructure.Services.PdfProcessing;
 using FluentAssertions;
 
@@ -47,6 +47,11 @@ public class DevExpressPdfProcessorTests
         return memoryStream.ToArray();
     }
 
+    /// <summary>
+    /// Converts byte array to MemoryStream for testing
+    /// </summary>
+    private static MemoryStream ToStream(byte[] bytes) => new MemoryStream(bytes);
+
     #endregion
 
     #region ValidateAsync Tests
@@ -58,7 +63,7 @@ public class DevExpressPdfProcessorTests
         byte[] pdfBytes = LoadTestPdf("valid.pdf");
 
         // Act
-        var metadata = await _sut.ValidateAsync(pdfBytes);
+        var metadata = await _sut.ValidateAsync(ToStream(pdfBytes));
 
         // Assert
         metadata.Should().NotBeNull("a valid PDF should return metadata");
@@ -74,7 +79,7 @@ public class DevExpressPdfProcessorTests
         byte[] pdfBytes = LoadTestPdf("valid.pdf");
 
         // Act
-        var metadata = await _sut.ValidateAsync(pdfBytes);
+        var metadata = await _sut.ValidateAsync(ToStream(pdfBytes));
 
         // Assert
         // Deine valid.pdf hat wahrscheinlich 1-5 Seiten - passe an!
@@ -82,30 +87,30 @@ public class DevExpressPdfProcessorTests
     }
 
     [Fact]
-    public async Task ValidateAsync_NullBytes_ThrowsPdfProcessingException()
+    public async Task ValidateAsync_NullStream_ThrowsArgumentNullException()
     {
         // Arrange
-        byte[]? pdfBytes = null;
+        Stream? pdfStream = null;
 
         // Act
-        Func<Task> act = async () => await _sut.ValidateAsync(pdfBytes!);
+        Func<Task> act = async () => await _sut.ValidateAsync(pdfStream!);
 
         // Assert
-        await act.Should().ThrowAsync<PdfProcessingException>()
-            .WithMessage("*null*", "null input should be rejected");
+        await act.Should().ThrowAsync<ArgumentNullException>()
+            .WithMessage("*pdfStream*", "null input should be rejected");
     }
 
     [Fact]
-    public async Task ValidateAsync_EmptyBytes_ThrowsPdfProcessingException()
+    public async Task ValidateAsync_EmptyStream_ThrowsBadRequestException()
     {
         // Arrange
-        byte[] pdfBytes = Array.Empty<byte>();
+        var pdfStream = new MemoryStream();
 
         // Act
-        Func<Task> act = async () => await _sut.ValidateAsync(pdfBytes);
+        Func<Task> act = async () => await _sut.ValidateAsync(pdfStream);
 
         // Assert
-        await act.Should().ThrowAsync<PdfProcessingException>()
+        await act.Should().ThrowAsync<BadRequestException>()
             .WithMessage("*empty*", "empty input should be rejected");
     }
 
@@ -116,10 +121,10 @@ public class DevExpressPdfProcessorTests
         byte[] pdfBytes = "This is not a valid PDF content"u8.ToArray();
 
         // Act
-        Func<Task> act = async () => await _sut.ValidateAsync(pdfBytes);
+        Func<Task> act = async () => await _sut.ValidateAsync(ToStream(pdfBytes));
 
         // Assert
-        await act.Should().ThrowAsync<PdfProcessingException>()
+        await act.Should().ThrowAsync<Exception>()
             .WithMessage("*valid pdf*", "corrupted PDF should throw exception");
     }
 
@@ -134,7 +139,7 @@ public class DevExpressPdfProcessorTests
         byte[] pdfBytes = LoadTestPdf("valid.pdf");
 
         // Act
-        var metadata = await _sut.ValidateAsync(pdfBytes);
+        var metadata = await _sut.ValidateAsync(ToStream(pdfBytes));
 
         // Assert
         double expectedSizeMB = pdfBytes.Length / 1024.0 / 1024.0;
@@ -153,7 +158,7 @@ public class DevExpressPdfProcessorTests
         byte[] pdfBytes = LoadTestPdf("valid.pdf");
 
         // Act
-        var metadata = await _sut.ValidateAsync(pdfBytes);
+        var metadata = await _sut.ValidateAsync(ToStream(pdfBytes));
 
         // Assert
         // Note: valid.pdf actually contains /EmbeddedFiles reference (15 0 R)
@@ -169,7 +174,7 @@ public class DevExpressPdfProcessorTests
         byte[] pdfBytes = LoadTestPdf("pdfWithMoreThanOneAttachment.pdf");
 
         // Act
-        var metadata = await _sut.ValidateAsync(pdfBytes);
+        var metadata = await _sut.ValidateAsync(ToStream(pdfBytes));
 
         // Assert
         metadata.HasAttachments.Should().BeTrue("PDF has multiple attachments");
@@ -182,4 +187,96 @@ public class DevExpressPdfProcessorTests
     // For now, we verify that attachment detection works (returns false for PDFs without attachments).
 
     #endregion
+
+    #region CheckAttachmentsAsync Tests
+
+    [Fact]
+    public async Task CheckAttachmentsAsync_PdfWithoutAttachments_ReturnsEmptyList()
+    {
+        // Arrange
+        byte[] pdfBytes = LoadTestPdf("pdfWithSwissQRCode.pdf");
+
+        // Act
+        var attachmentInfo = await _sut.CheckAttachmentsAsync(ToStream(pdfBytes));
+
+        // Assert
+        attachmentInfo.Should().NotBeNull("CheckAttachmentsAsync should return non-null result");
+        attachmentInfo.HasAttachments.Should().BeFalse("Swiss QR PDF has no attachments");
+        attachmentInfo.AttachmentCount.Should().Be(0, "Swiss QR PDF has no attachments");
+        attachmentInfo.Attachments.Should().BeEmpty("Swiss QR PDF has no attachments");
+    }
+
+    [Fact]
+    public async Task CheckAttachmentsAsync_PdfWithMultipleAttachments_ReturnsCorrectMetadata()
+    {
+        // Arrange
+        byte[] pdfBytes = LoadTestPdf("pdfWithMoreThanOneAttachment.pdf");
+
+        // Act
+        var attachmentInfo = await _sut.CheckAttachmentsAsync(ToStream(pdfBytes));
+
+        // Assert
+        attachmentInfo.Should().NotBeNull("CheckAttachmentAsync should return non-null result");
+        attachmentInfo.HasAttachments.Should().BeTrue("PDF has 6 attachments");
+        attachmentInfo.AttachmentCount.Should().Be(6, "PDF has exactly 6 attachments");
+        attachmentInfo.Attachments.Should().HaveCount(6, "Attachments list should contain 6 items");
+
+        // Verify each attachment has required properties
+        foreach (var attachment in attachmentInfo.Attachments)
+        {
+            attachment.FileName.Should().NotBeNullOrEmpty("each attachment must have a file name");
+            attachment.MimeType.Should().NotBeNullOrEmpty("each attachment must have a MIME type");
+            attachment.SizeBytes.Should().BeGreaterThan(0, "each attachment must have a size > 0");
+        }
+    }
+
+    [Fact]
+    public async Task CheckAttachmentsAsync_ValidPdf_HasAttachments()
+    {
+        // Arrange
+        byte[] pdfBytes = LoadTestPdf("valid.pdf");
+
+        // Act
+        var attachmentInfo = await _sut.CheckAttachmentsAsync(ToStream(pdfBytes));
+
+        // Assert
+        attachmentInfo.Should().NotBeNull("CheckAttachmentsAsync should return non-null result");
+        // Note: valid.pdf contains embedded files (tested and confirmed)
+        attachmentInfo.HasAttachments.Should().BeTrue("valid.pdf contains attachments");
+        attachmentInfo.AttachmentCount.Should().BeGreaterThan(0, "valid.pdf has at least one attachment");
+    }
+
+    [Fact]
+    public async Task CheckAttachmentsAsync_EmptyBytes_ThrowsBadRequestException()
+    {
+        // Arrange
+        var pdfStream = new MemoryStream();
+
+        // Act
+        Func<Task> act = async () => await _sut.CheckAttachmentsAsync(pdfStream);
+
+        // Assert
+        await act.Should().ThrowAsync<BadRequestException>()
+            .WithMessage("*empty*", "empty input should be rejected");
+    }
+
+    [Fact]
+    public async Task CheckAttachmentsAsync_CorruptedPdf_ThrowsException()
+    {
+        // Arrange
+        byte[] pdfBytes = "This is not a valid PDF content"u8.ToArray();
+
+        // Act
+        Func<Task> act = async () => await _sut.CheckAttachmentsAsync(ToStream(pdfBytes));
+
+        // Assert
+        // DevExpress throws ArgumentException for invalid PDF data
+        await act.Should().ThrowAsync<Exception>("corrupted PDF should throw exception");
+    }
+
+    #endregion
 }
+
+
+
+