Consolidate AIContent roundtrip tests: combine separate tests, remove duplicative ones

- Merge *_ToAIContent_PreservesData and *_ToAIContent_RoundTrips into single tests
  that validate both the intermediate DataContent and the roundtripped block
- Remove duplicative DataContent_*ToContentBlock_PreservesData tests (already covered
  by the roundtrip tests)
- Add missing MediaType assertions on intermediate DataContent for *_DataSetter and
  *_BlobSetter test variants

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

tests/ModelContextProtocol.Tests/AIContentExtensionsTests.cs

@@ -429,28 +429,17 @@ public static TheoryData<byte[]> Base64TestData()
         return data;
     }
 
-    [Theory]
-    [MemberData(nameof(Base64TestData))]
-    public void ImageContentBlock_ToAIContent_PreservesData(byte[] originalBytes)
-    {
-        var image = ImageContentBlock.FromBytes(originalBytes, "image/png");
-
-        var aiContent = image.ToAIContent();
-
-        var dataContent = Assert.IsType<DataContent>(aiContent);
-        Assert.Equal("image/png", dataContent.MediaType);
-        Assert.Equal(originalBytes, dataContent.Data.ToArray());
-    }
-
     [Theory]
     [MemberData(nameof(Base64TestData))]
     public void ImageContentBlock_ToAIContent_RoundTrips(byte[] originalBytes)
     {
         var image = ImageContentBlock.FromBytes(originalBytes, "image/png");
 
         var aiContent = Assert.IsType<DataContent>(image.ToAIContent());
-        var roundTripped = Assert.IsType<ImageContentBlock>(aiContent.ToContentBlock());
+        Assert.Equal("image/png", aiContent.MediaType);
+        Assert.Equal(originalBytes, aiContent.Data.ToArray());
 
+        var roundTripped = Assert.IsType<ImageContentBlock>(aiContent.ToContentBlock());
         Assert.Equal("image/png", roundTripped.MimeType);
         Assert.Equal(originalBytes, roundTripped.DecodedData.ToArray());
     }
@@ -467,35 +456,25 @@ public void ImageContentBlock_DataSetter_ToAIContent_RoundTrips(byte[] originalB
         };
 
         var aiContent = Assert.IsType<DataContent>(image.ToAIContent());
+        Assert.Equal("image/jpeg", aiContent.MediaType);
         Assert.Equal(originalBytes, aiContent.Data.ToArray());
 
         var roundTripped = Assert.IsType<ImageContentBlock>(aiContent.ToContentBlock());
         Assert.Equal("image/jpeg", roundTripped.MimeType);
         Assert.Equal(originalBytes, roundTripped.DecodedData.ToArray());
     }
 
-    [Theory]
-    [MemberData(nameof(Base64TestData))]
-    public void AudioContentBlock_ToAIContent_PreservesData(byte[] originalBytes)
-    {
-        var audio = AudioContentBlock.FromBytes(originalBytes, "audio/wav");
-
-        var aiContent = audio.ToAIContent();
-
-        var dataContent = Assert.IsType<DataContent>(aiContent);
-        Assert.Equal("audio/wav", dataContent.MediaType);
-        Assert.Equal(originalBytes, dataContent.Data.ToArray());
-    }
-
     [Theory]
     [MemberData(nameof(Base64TestData))]
     public void AudioContentBlock_ToAIContent_RoundTrips(byte[] originalBytes)
     {
         var audio = AudioContentBlock.FromBytes(originalBytes, "audio/wav");
 
         var aiContent = Assert.IsType<DataContent>(audio.ToAIContent());
-        var roundTripped = Assert.IsType<AudioContentBlock>(aiContent.ToContentBlock());
+        Assert.Equal("audio/wav", aiContent.MediaType);
+        Assert.Equal(originalBytes, aiContent.Data.ToArray());
 
+        var roundTripped = Assert.IsType<AudioContentBlock>(aiContent.ToContentBlock());
         Assert.Equal("audio/wav", roundTripped.MimeType);
         Assert.Equal(originalBytes, roundTripped.DecodedData.ToArray());
     }
@@ -512,27 +491,14 @@ public void AudioContentBlock_DataSetter_ToAIContent_RoundTrips(byte[] originalB
         };
 
         var aiContent = Assert.IsType<DataContent>(audio.ToAIContent());
+        Assert.Equal("audio/mp3", aiContent.MediaType);
         Assert.Equal(originalBytes, aiContent.Data.ToArray());
 
         var roundTripped = Assert.IsType<AudioContentBlock>(aiContent.ToContentBlock());
         Assert.Equal("audio/mp3", roundTripped.MimeType);
         Assert.Equal(originalBytes, roundTripped.DecodedData.ToArray());
     }
 
-    [Theory]
-    [MemberData(nameof(Base64TestData))]
-    public void BlobResourceContents_ToAIContent_PreservesData(byte[] originalBytes)
-    {
-        var blob = BlobResourceContents.FromBytes(originalBytes, "file:///test.bin", "application/octet-stream");
-        var embedded = new EmbeddedResourceBlock { Resource = blob };
-
-        var aiContent = embedded.ToAIContent();
-
-        var dataContent = Assert.IsType<DataContent>(aiContent);
-        Assert.Equal("application/octet-stream", dataContent.MediaType);
-        Assert.Equal(originalBytes, dataContent.Data.ToArray());
-    }
-
     [Theory]
     [MemberData(nameof(Base64TestData))]
     public void BlobResourceContents_ToAIContent_RoundTrips(byte[] originalBytes)
@@ -541,9 +507,11 @@ public void BlobResourceContents_ToAIContent_RoundTrips(byte[] originalBytes)
         var embedded = new EmbeddedResourceBlock { Resource = blob };
 
         var aiContent = Assert.IsType<DataContent>(embedded.ToAIContent());
+        Assert.Equal("application/octet-stream", aiContent.MediaType);
+        Assert.Equal(originalBytes, aiContent.Data.ToArray());
+
         var roundTripped = Assert.IsType<EmbeddedResourceBlock>(aiContent.ToContentBlock());
         var roundTrippedBlob = Assert.IsType<BlobResourceContents>(roundTripped.Resource);
-
         Assert.Equal("application/octet-stream", roundTrippedBlob.MimeType);
         Assert.Equal(originalBytes, roundTrippedBlob.DecodedData.ToArray());
     }
@@ -562,6 +530,7 @@ public void BlobResourceContents_BlobSetter_ToAIContent_RoundTrips(byte[] origin
         var embedded = new EmbeddedResourceBlock { Resource = blob };
 
         var aiContent = Assert.IsType<DataContent>(embedded.ToAIContent());
+        Assert.Equal("application/octet-stream", aiContent.MediaType);
         Assert.Equal(originalBytes, aiContent.Data.ToArray());
 
         var roundTripped = Assert.IsType<EmbeddedResourceBlock>(aiContent.ToContentBlock());
@@ -570,46 +539,6 @@ public void BlobResourceContents_BlobSetter_ToAIContent_RoundTrips(byte[] origin
         Assert.Equal(originalBytes, roundTrippedBlob.DecodedData.ToArray());
     }
 
-    [Theory]
-    [MemberData(nameof(Base64TestData))]
-    public void DataContent_ImageToContentBlock_PreservesData(byte[] originalBytes)
-    {
-        var dataContent = new DataContent(originalBytes, "image/png");
-
-        var contentBlock = dataContent.ToContentBlock();
-
-        var image = Assert.IsType<ImageContentBlock>(contentBlock);
-        Assert.Equal("image/png", image.MimeType);
-        Assert.Equal(originalBytes, image.DecodedData.ToArray());
-    }
-
-    [Theory]
-    [MemberData(nameof(Base64TestData))]
-    public void DataContent_AudioToContentBlock_PreservesData(byte[] originalBytes)
-    {
-        var dataContent = new DataContent(originalBytes, "audio/wav");
-
-        var contentBlock = dataContent.ToContentBlock();
-
-        var audio = Assert.IsType<AudioContentBlock>(contentBlock);
-        Assert.Equal("audio/wav", audio.MimeType);
-        Assert.Equal(originalBytes, audio.DecodedData.ToArray());
-    }
-
-    [Theory]
-    [MemberData(nameof(Base64TestData))]
-    public void DataContent_BlobToContentBlock_PreservesData(byte[] originalBytes)
-    {
-        var dataContent = new DataContent(originalBytes, "application/octet-stream");
-
-        var contentBlock = dataContent.ToContentBlock();
-
-        var embedded = Assert.IsType<EmbeddedResourceBlock>(contentBlock);
-        var blob = Assert.IsType<BlobResourceContents>(embedded.Resource);
-        Assert.Equal("application/octet-stream", blob.MimeType);
-        Assert.Equal(originalBytes, blob.DecodedData.ToArray());
-    }
-
     [Theory]
     [MemberData(nameof(Base64TestData))]
     public void ImageContentBlock_JsonDeserialized_ToAIContent_RoundTrips(byte[] originalBytes)