Support blank column names and enable more integration tests.

csharp/src/Apache.Arrow/Field.Builder.cs

@@ -30,14 +30,13 @@ public class Builder
 
             public Builder()
             {
-                _name = string.Empty;
                 _type = NullType.Default;
                 _nullable = true;
             }
 
             public Builder Name(string value)
             {
-                if (string.IsNullOrWhiteSpace(value))
+                if (value == null)
                 {
                     throw new ArgumentNullException(nameof(value));
                 }

csharp/src/Apache.Arrow/Field.cs

@@ -35,24 +35,23 @@ public partial class Field
 
         public Field(string name, IArrowType dataType, bool nullable,
             IEnumerable<KeyValuePair<string, string>> metadata = default)
-            : this(name, dataType, nullable, false)
+            : this(name, dataType, nullable)
         {
             Metadata = metadata?.ToDictionary(kv => kv.Key, kv => kv.Value);
-
         }
 
         internal Field(string name, IArrowType dataType, bool nullable,
-            IReadOnlyDictionary<string, string> metadata, bool copyCollections, bool allowBlankName)
-            : this(name, dataType, nullable, allowBlankName)
+            IReadOnlyDictionary<string, string> metadata, bool copyCollections)
+            : this(name, dataType, nullable)
         {
             Debug.Assert(copyCollections == false, "This internal constructor is to not copy the collections.");
 
             Metadata = metadata;
         }
 
-        private Field(string name, IArrowType dataType, bool nullable, bool allowBlankName)
+        private Field(string name, IArrowType dataType, bool nullable)
         {
-            if (name == null || (!allowBlankName && string.IsNullOrWhiteSpace(name)))
+            if (name == null)
             {
                 throw new ArgumentNullException(nameof(name));
             }

csharp/src/Apache.Arrow/Ipc/MessageSerializer.cs

@@ -59,7 +59,7 @@ internal static Schema GetSchema(Flatbuf.Schema schema, ref DictionaryMemo dicti
             for (int i = 0; i < schema.FieldsLength; i++)
             {
                 Flatbuf.Field field = schema.Fields(i).GetValueOrDefault();
-                fields.Add(FieldFromFlatbuffer(field, ref dictionaryMemo, allowBlankName: false));
+                fields.Add(FieldFromFlatbuffer(field, ref dictionaryMemo));
             }
 
             Dictionary<string, string> metadata = schema.CustomMetadataLength > 0 ? new Dictionary<string, string>() : null;
@@ -73,14 +73,13 @@ internal static Schema GetSchema(Flatbuf.Schema schema, ref DictionaryMemo dicti
             return new Schema(fields, metadata, copyCollections: false);
         }
 
-        private static Field FieldFromFlatbuffer(Flatbuf.Field flatbufField, ref DictionaryMemo dictionaryMemo, bool allowBlankName)
+        private static Field FieldFromFlatbuffer(Flatbuf.Field flatbufField, ref DictionaryMemo dictionaryMemo)
         {
-            bool allowBlankNameChild = flatbufField.ChildrenLength == 1 && flatbufField.TypeType == Flatbuf.Type.FixedSizeList;
             Field[] childFields = flatbufField.ChildrenLength > 0 ? new Field[flatbufField.ChildrenLength] : null;
             for (int i = 0; i < flatbufField.ChildrenLength; i++)
             {
                 Flatbuf.Field? childFlatbufField = flatbufField.Children(i);
-                childFields[i] = FieldFromFlatbuffer(childFlatbufField.Value, ref dictionaryMemo, allowBlankNameChild);
+                childFields[i] = FieldFromFlatbuffer(childFlatbufField.Value, ref dictionaryMemo);
             }
 
             Flatbuf.DictionaryEncoding? dictionaryEncoding = flatbufField.Dictionary;
@@ -104,7 +103,7 @@ private static Field FieldFromFlatbuffer(Flatbuf.Field flatbufField, ref Diction
                 metadata[keyValue.Key] = keyValue.Value;
             }
 
-            var arrowField = new Field(flatbufField.Name, type, flatbufField.Nullable, metadata, copyCollections: false, allowBlankName);
+            var arrowField = new Field(flatbufField.Name, type, flatbufField.Nullable, metadata, copyCollections: false);
 
             if (dictionaryEncoding.HasValue)
             {

csharp/test/Apache.Arrow.IntegrationTest/JsonFile.cs

@@ -120,6 +120,12 @@ private static Schema CreateSchema(JsonSchema jsonSchema, Dictionary<DictionaryT
             {
                 builder.Field(f => CreateField(f, jsonSchema.Fields[i], dictionaryIndexes));
             }
+
+            if (jsonSchema.Metadata != null)
+            {
+                builder.Metadata(jsonSchema.Metadata);
+            }
+
             return builder.Build();
         }
 

csharp/test/Apache.Arrow.Tests/CDataInterfacePythonTests.cs

@@ -829,6 +829,50 @@ public unsafe void ExportArrayStream()
             CArrowArrayStream.Free(cArrayStream);
         }
 
+        [SkippableFact]
+        public unsafe void ImportRecordBatchFromBuffer()
+        {
+            using (Py.GIL())
+            {
+                dynamic pa = Py.Import("pyarrow");
+                dynamic batch = pa.record_batch(
+                    new PyList(new PyObject[]
+                    {
+                        pa.array(new long?[] { 1, 2, 3, null, 5 }),
+                        pa.array(new[] { "hello", "world", null, "foo", "bar" }),
+                        pa.array(new[] { 0.0, 1.4, 2.5, 3.6, 4.7 }),
+                        pa.array(new bool?[] { true, false, null, false, true }),
+                    }),
+                    new[] { null, "", "column", "column" });
+
+                dynamic sink = pa.BufferOutputStream();
+                dynamic writer = pa.ipc.new_stream(sink, batch.schema);
+                writer.write_batch(batch);
+                ((IDisposable)writer).Dispose();
+
+                dynamic buf = sink.getvalue();
+                // buf.address, buf.size
+
+                IntPtr address = (IntPtr)(long)buf.address;
+                int size = buf.size;
+                byte[] buffer = new byte[size];
+                byte* ptr = (byte*)address.ToPointer();
+                for (int i = 0; i < size; i++)
+                {
+                    buffer[i] = ptr[i];
+                }
+
+                using (ArrowStreamReader reader = new ArrowStreamReader(new ReadOnlyMemory<byte>(buffer)))
+                {
+                    RecordBatch batch2 = reader.ReadNextRecordBatch();
+                    Assert.Equal("None", batch2.Schema.FieldsList[0].Name);
+                    Assert.Equal("", batch2.Schema.FieldsList[1].Name);
+                    Assert.Equal("column", batch2.Schema.FieldsList[2].Name);
+                    Assert.Equal("column", batch2.Schema.FieldsList[3].Name);
+                }
+            }
+        }
+
         private static PyObject List(params int?[] values)
         {
             return new PyList(values.Select(i => i == null ? PyObject.None : new PyInt(i.Value)).ToArray());

dev/archery/archery/integration/datagen.py

@@ -1812,7 +1812,6 @@ def _temp_path():
         generate_map_case(),
 
         generate_non_canonical_map_case()
-        .skip_tester('C#')
         .skip_tester('Java')  # TODO(ARROW-8715)
         # Canonical map names are restored on import, so the schemas are unequal
         .skip_format(SKIP_C_SCHEMA, 'C++'),
@@ -1827,11 +1826,9 @@ def _temp_path():
 
         generate_unions_case(),
 
-        generate_custom_metadata_case()
-        .skip_tester('C#'),
+        generate_custom_metadata_case(),
 
         generate_duplicate_fieldnames_case()
-        .skip_tester('C#')
         .skip_tester('JS'),
 
         generate_dictionary_case(),
@@ -1856,7 +1853,6 @@ def _temp_path():
         .skip_tester('Rust'),
 
         generate_extension_case()
-        .skip_tester('C#')
         # TODO: ensure the extension is registered in the C++ entrypoint
         .skip_format(SKIP_C_SCHEMA, 'C++')
         .skip_format(SKIP_C_ARRAY, 'C++'),