diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/.editorconfig b/src/Microsoft.Data.SqlClient/tests/UnitTests/.editorconfig
new file mode 100644
index 0000000000..c75dd30b68
--- /dev/null
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/.editorconfig
@@ -0,0 +1,11 @@
+# editorconfig.org
+
+# top-most EditorConfig file
+root = false
+
+[*.cs]
+
+csharp_style_var_when_type_is_apparent = false:refactor
+# IDE0090: Use 'new(...)'
+csharp_style_implicit_object_creation_when_type_is_apparent = true:warning
+
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/InternalsVisibleToTest.cs b/src/Microsoft.Data.SqlClient/tests/UnitTests/InternalsVisibleToTest.cs
index eb924990db..36621fcb51 100644
--- a/src/Microsoft.Data.SqlClient/tests/UnitTests/InternalsVisibleToTest.cs
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/InternalsVisibleToTest.cs
@@ -4,8 +4,14 @@
namespace Microsoft.Data.SqlClient.UnitTests
{
+ ///
+ /// Tests proving that the InternalsVisibleTo attribute works correctly.
+ ///
public class InternalsVisibleToTest
{
+ ///
+ /// Creates an instance of an internal class. Verifies that this compiles.
+ ///
[Fact]
public void TestInternalsVisible()
{
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft.Data.SqlClient.UnitTests.csproj b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft.Data.SqlClient.UnitTests.csproj
index 2f0e12c922..cb9ea86243 100644
--- a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft.Data.SqlClient.UnitTests.csproj
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft.Data.SqlClient.UnitTests.csproj
@@ -7,6 +7,8 @@
$(ObjFolder)$(Configuration).$(Platform).$(AssemblyName)
$(BinFolder)$(Configuration).$(Platform).$(AssemblyName)
true
+ true
+ enable
@@ -25,6 +27,7 @@
all
+
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPoolTest.cs b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPoolTest.cs
index 2dcfe476fe..671c1428dd 100644
--- a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPoolTest.cs
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPoolTest.cs
@@ -11,6 +11,7 @@
namespace Microsoft.Data.SqlClient.UnitTests
{
+#pragma warning disable CS1591 // Test classes do not require XML documentation comments
public class ChannelDbConnectionPoolTest
{
private readonly ChannelDbConnectionPool _pool;
@@ -152,4 +153,5 @@ public void TestTryGetConnection()
Assert.Throws(() => _pool.TryGetConnection(null!, null!, null!, out _));
}
}
+#pragma warning restore CS1591
}
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/InvalidSerializationTest.cs b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/InvalidSerializationTest.cs
new file mode 100644
index 0000000000..bee1db5838
--- /dev/null
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/InvalidSerializationTest.cs
@@ -0,0 +1,62 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.IO;
+using Microsoft.Data.SqlClient.Server;
+using Microsoft.Data.SqlClient.UnitTests.UdtSerialization.SerializedTypes;
+using Microsoft.SqlServer.Server;
+using Xunit;
+
+namespace Microsoft.Data.SqlClient.UnitTests.UdtSerialization;
+
+///
+/// Attempts to serialize types which do not meet the requirements for either user-defined or native serialization.
+///
+public sealed class InvalidSerializationTest : IDisposable
+{
+ private readonly MemoryStream _stream;
+
+ ///
+ /// Initializes the MemoryStream used for all tests in this class.
+ ///
+ public InvalidSerializationTest()
+ {
+ _stream = new MemoryStream();
+ }
+
+ void IDisposable.Dispose()
+ {
+ _stream.Dispose();
+ }
+
+ ///
+ /// Attempts to serialize a class that does not have the SqlUserDefinedType attribute. Verifies that this fails.
+ ///
+ [Fact]
+ public void RequiresSqlUserDefinedTypeAttribute()
+ {
+ var exception = Assert.Throws(
+ () => SerializationHelperSql9.Serialize(_stream, new ClassMissingSqlUserDefinedTypeAttribute()));
+
+ Assert.Equal($"'{typeof(ClassMissingSqlUserDefinedTypeAttribute).FullName}' is an invalid user defined type, reason: no UDT attribute.", exception.Message);
+ }
+
+ ///
+ /// Attempts to serialize a class that has a SqlUserDefinedType attribute, but specifies a Format enumeration value of
+ /// Unknown. Verifies that this fails.
+ ///
+ [Fact]
+ public void CannotSerializeUnknownFormattedType()
+ {
+ var exception = Assert.Throws("Format",
+ () => SerializationHelperSql9.Serialize(_stream, new UnknownFormattedClass()));
+
+#if NET
+ Assert.Equal("The Format enumeration value, 0, is not supported by the format method. (Parameter 'Format')", exception.Message);
+#else
+ Assert.Equal("The Format enumeration value, Unknown, is not supported by the format method.\r\nParameter name: Format", exception.Message);
+#endif
+ }
+}
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/NativeSerializationTest.cs b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/NativeSerializationTest.cs
new file mode 100644
index 0000000000..e37e862e99
--- /dev/null
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/NativeSerializationTest.cs
@@ -0,0 +1,290 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.Data.SqlClient.Server;
+using Microsoft.Data.SqlClient.UnitTests.UdtSerialization.SerializedTypes;
+using System;
+using System.Collections.Generic;
+using System.Data.SqlTypes;
+using System.IO;
+using Xunit;
+
+namespace Microsoft.Data.SqlClient.UnitTests.UdtSerialization;
+
+///
+/// Tests the serialization method defined by MS-SSCLRT. Ensures that combinations of primitives and custom types round-trip.
+///
+///
+public sealed class NativeSerializationTest : IDisposable
+{
+ private readonly MemoryStream _stream;
+
+ ///
+ /// Initializes the MemoryStream used for all tests in this class.
+ ///
+ public NativeSerializationTest()
+ {
+ _stream = new MemoryStream();
+ }
+
+ void IDisposable.Dispose()
+ {
+ _stream.Dispose();
+ }
+
+ ///
+ /// Provides a collection of test data representing non-null primitive type values and their corresponding
+ /// serialized byte arrays.
+ ///
+ ///
+ public static IEnumerable SerializedNonNullPrimitiveTypeValues()
+ {
+ yield return [new BoolWrapperStruct { Field1 = true },
+ new byte[] { 0x01 }];
+ yield return [new ByteWrapperStruct { Field1 = 0x20 },
+ new byte[] { 0x20 }];
+ yield return [new SByteWrapperStruct { Field1 = -0x1 },
+ new byte[] { 0x7F }];
+ yield return [new UShortWrapperStruct { Field1 = 0x8000 },
+ new byte[] { 0x80, 0x00 }];
+ yield return [new ShortWrapperStruct { Field1 = 0x1234 },
+ new byte[] { 0x92, 0x34 }];
+ yield return [new UIntWrapperStruct { Field1 = 0xFFFFFFFF },
+ new byte[] { 0xFF, 0xFF, 0xFF, 0xFF }];
+ yield return [new IntWrapperStruct { Field1 = -0x12345678 },
+ new byte[] { 0x6D, 0xCB, 0xA9, 0x88 }];
+ yield return [new ULongWrapperStruct { Field1 = ulong.MaxValue },
+ new byte[] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }];
+ yield return [new LongWrapperStruct { Field1 = long.MinValue },
+ new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }];
+ yield return [new FloatWrapperStruct { Field1 = -0 },
+ new byte[] { 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new DoubleWrapperStruct { Field1 = Math.PI },
+ new byte[] { 0xC0, 0x09, 0x21, 0xFB, 0x54, 0x44, 0x2D, 0x18 }];
+ yield return [new SqlByteWrapperStruct { Field1 = 0x20 },
+ new byte[] { 0x01, 0x20 }];
+ yield return [new SqlInt16WrapperStruct { Field1 = 0x1234 },
+ new byte[] { 0x01, 0x92, 0x34 }];
+ yield return [new SqlInt32WrapperStruct { Field1 = -0x12345678 },
+ new byte[] { 0x01, 0x6D, 0xCB, 0xA9, 0x88 }];
+ yield return [new SqlInt64WrapperStruct { Field1 = long.MinValue },
+ new byte[] { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }];
+ yield return [new SqlBooleanWrapperStruct { Field1 = false },
+ new byte[] { 0x01 }];
+ yield return [new SqlSingleWrapperStruct { Field1 = -1 },
+ new byte[] { 0x01, 0x40, 0x7F, 0xFF, 0xFF }];
+ yield return [new SqlDoubleWrapperStruct { Field1 = -Math.PI },
+ new byte[] { 0x01, 0x3F, 0xF6, 0xDE, 0x04, 0xAB, 0xBB, 0xD2, 0xE7 }];
+ yield return [new SqlDateTimeWrapperStruct { Field1 = new DateTime(2000, 1, 1, 12, 34, 56, 500) },
+ new byte[] { 0x01, 0x80, 0x00, 0x8E, 0xAC, 0x80, 0xCF, 0x59, 0xD6 }];
+ yield return [new SqlMoneyWrapperStruct { Field1 = 1.10m },
+ new byte[] { 0x01, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2A, 0xF8 }];
+ }
+
+ ///
+ /// Provides a collection of test data representing serialized values of nested non-null primitive types.
+ ///
+ ///
+ public static IEnumerable SerializedNestedNonNullPrimitiveTypeValues()
+ {
+ yield return [new NestedBoolWrapperStruct { Field1 = true, Field2 = new BoolWrapperStruct { Field1 = false } },
+ new byte[] { 0x01,
+ 0x00 }];
+ yield return [new NestedByteWrapperStruct { Field1 = 0x20, Field2 = new ByteWrapperStruct { Field1 = 0x30 } },
+ new byte[] { 0x20,
+ 0x30 }];
+ yield return [new NestedSByteWrapperStruct { Field1 = -0x01, Field2 = new SByteWrapperStruct { Field1 = 0x01 } },
+ new byte[] { 0x7F,
+ 0x81 }];
+ yield return [new NestedUShortWrapperStruct { Field1 = 0x8000, Field2 = new UShortWrapperStruct { Field1 = 0x8014 } },
+ new byte[] { 0x80, 0x00,
+ 0x80, 0x14 }];
+ yield return [new NestedShortWrapperStruct { Field1 = 0x1234, Field2 = new ShortWrapperStruct { Field1 = 0x4321 } },
+ new byte[] { 0x92, 0x34,
+ 0xC3, 0x21 }];
+ yield return [new NestedUIntWrapperStruct { Field1 = 0xFFFFFFFF, Field2 = new UIntWrapperStruct { Field1 = 0x00000000 } },
+ new byte[] { 0xFF, 0xFF, 0xFF, 0xFF,
+ 0x00, 0x00, 0x00, 0x00 }];
+ yield return [new NestedIntWrapperStruct { Field1 = -0x12345678, Field2 = new IntWrapperStruct { Field1 = 0x12345678 } },
+ new byte[] { 0x6D, 0xCB, 0xA9, 0x88,
+ 0x92, 0x34, 0x56, 0x78 }];
+ yield return [new NestedULongWrapperStruct { Field1 = ulong.MaxValue, Field2 = new ULongWrapperStruct { Field1 = long.MaxValue } },
+ new byte[] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+ 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }];
+ yield return [new NestedLongWrapperStruct { Field1 = long.MinValue, Field2 = new LongWrapperStruct { Field1 = long.MaxValue } },
+ new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }];
+ yield return [new NestedFloatWrapperStruct { Field1 = -0, Field2 = new FloatWrapperStruct { Field1 = +0 } },
+ new byte[] { 0x80, 0x00, 0x00, 0x00,
+ 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new NestedDoubleWrapperStruct { Field1 = Math.PI, Field2 = new DoubleWrapperStruct { Field1 = Math.PI } },
+ new byte[] { 0xC0, 0x09, 0x21, 0xFB, 0x54, 0x44, 0x2D, 0x18,
+ 0xC0, 0x09, 0x21, 0xFB, 0x54, 0x44, 0x2D, 0x18 }];
+ yield return [new NestedSqlByteWrapperStruct { Field1 = 0x20, Field2 = new SqlByteWrapperStruct { Field1 = 0x30 } },
+ new byte[] { 0x01, 0x20,
+ 0x01, 0x30 }];
+ yield return [new NestedSqlInt16WrapperStruct { Field1 = 0x1234, Field2 = new SqlInt16WrapperStruct { Field1 = 0x4321 } },
+ new byte[] { 0x01, 0x92, 0x34,
+ 0x01, 0xC3, 0x21 }];
+ yield return [new NestedSqlInt32WrapperStruct { Field1 = -0x12345678, Field2 = new SqlInt32WrapperStruct { Field1 = 0x12345678 } },
+ new byte[] { 0x01, 0x6D, 0xCB, 0xA9, 0x88,
+ 0x01, 0x92, 0x34, 0x56, 0x78 }];
+ yield return [new NestedSqlInt64WrapperStruct { Field1 = long.MinValue, Field2 = new SqlInt64WrapperStruct { Field1 = long.MaxValue } },
+ new byte[] { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x01, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }];
+ yield return [new NestedSqlBooleanWrapperStruct { Field1 = false, Field2 = new SqlBooleanWrapperStruct { Field1 = true } },
+ new byte[] { 0x01,
+ 0x02 }];
+ yield return [new NestedSqlSingleWrapperStruct { Field1 = -0, Field2 = new SqlSingleWrapperStruct { Field1 = +0 } },
+ new byte[] { 0x01, 0x80, 0x00, 0x00, 0x00,
+ 0x01, 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new NestedSqlDoubleWrapperStruct { Field1 = Math.PI, Field2 = new SqlDoubleWrapperStruct { Field1 = Math.PI } },
+ new byte[] { 0x01, 0xC0, 0x09, 0x21, 0xFB, 0x54, 0x44, 0x2D, 0x18,
+ 0x01, 0xC0, 0x09, 0x21, 0xFB, 0x54, 0x44, 0x2D, 0x18 }];
+ yield return [new NestedSqlDateTimeWrapperStruct { Field1 = new DateTime(2000, 1, 1, 12, 34, 56, 500), Field2 = new SqlDateTimeWrapperStruct { Field1 = new DateTime(2000, 1, 1) } },
+ new byte[] { 0x01, 0x80, 0x00, 0x8E, 0xAC, 0x80, 0xCF, 0x59, 0xD6,
+ 0x01, 0x80, 0x00, 0x8E, 0xAC, 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new NestedSqlMoneyWrapperStruct { Field1 = 1.10m, Field2 = new SqlMoneyWrapperStruct { Field1 = -2.55m } },
+ new byte[] { 0x01, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2A, 0xF8,
+ 0x01, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x9C, 0x64 }];
+ }
+
+ ///
+ /// Provides a collection of test data representing serialized null values for various primitive types.
+ ///
+ ///
+ public static IEnumerable SerializedNullPrimitiveTypeValues()
+ {
+ yield return [new SqlByteWrapperStruct { Field1 = SqlByte.Null },
+ new byte[] { 0x00, 0x00 }];
+ yield return [new SqlInt16WrapperStruct { Field1 = SqlInt16.Null },
+ new byte[] { 0x00, 0x80, 0x00 }];
+ yield return [new SqlInt32WrapperStruct { Field1 = SqlInt32.Null },
+ new byte[] { 0x00, 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new SqlInt64WrapperStruct { Field1 = SqlInt64.Null },
+ new byte[] { 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }];
+ yield return [new SqlBooleanWrapperStruct { Field1 = SqlBoolean.Null },
+ new byte[] { 0x00 }];
+ yield return [new SqlSingleWrapperStruct { Field1 = SqlSingle.Null },
+ new byte[] { 0x00, 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new SqlDoubleWrapperStruct { Field1 = SqlDouble.Null },
+ new byte[] { 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }];
+ yield return [new SqlDateTimeWrapperStruct { Field1 = SqlDateTime.Null },
+ new byte[] { 0x00, 0x80, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00 }];
+ yield return [new SqlMoneyWrapperStruct { Field1 = SqlMoney.Null },
+ new byte[] { 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }];
+ }
+
+ ///
+ /// Attempts to serialize various structs containing non-null primitive types.
+ /// Verifies that the method does not throw, that serialized byte output is correct, and that the value round-trips.
+ ///
+ /// Primitive to serialize and to compare against.
+ /// Expected byte output.
+ [Theory]
+ [MemberData(nameof(SerializedNonNullPrimitiveTypeValues))]
+ public void SerializePrimitiveType(object primitive, byte[] expectedValue)
+ => RoundtripType(primitive, expectedValue);
+
+ ///
+ /// Attempts to serialize a nested struct hierarchy containing non-null primitive types.
+ /// Verifies that the method does not throw, that serialized byte output is correct, and that the value round-trips.
+ ///
+ /// Primitive to serialize and to compare against.
+ /// Expected byte output.
+ [Theory]
+ [MemberData(nameof(SerializedNestedNonNullPrimitiveTypeValues))]
+ public void SerializeNestedPrimitiveType(object primitive, byte[] expectedValue)
+ => RoundtripType(primitive, expectedValue);
+
+ ///
+ /// Attempts to serialize various structs containing null-valued primitive types.
+ /// Verifies that the method does not throw, that serialized byte output is correct, and that the value round-trips.
+ ///
+ /// Primitive to serialize and to compare against.
+ /// Expected byte output.
+ [Theory]
+ [MemberData(nameof(SerializedNullPrimitiveTypeValues))]
+ public void SerializeNullPrimitiveType(object primitive, byte[] expectedValue)
+ => RoundtripType(primitive, expectedValue);
+
+ ///
+ /// Attempts to serialize an instance of a class.
+ ///
+ ///
+ [Fact]
+ public void CanSerializeTopLevelClass()
+ {
+ NestedBoolWrapperClass validWrapper = new()
+ {
+ Field1 = true,
+ Field2 = new BoolWrapperStruct() { Field1 = true }
+ };
+
+ SerializationHelperSql9.Serialize(_stream, validWrapper);
+ }
+
+ ///
+ /// Attempts to serialize a field referring to an instance of a class.
+ /// Verifies that this fails, and that Native format serialization only operates with primitive types and value types containing these.
+ ///
+ ///
+ [Fact]
+ public void CannotSerializeNestedClass()
+ {
+ InvalidNestedBoolWrapperClass invalidWrapper = new()
+ {
+ Field1 = true,
+ Field2 = new BoolWrapperClass() { Field1 = true }
+ };
+
+ var ex = Assert.Throws(() => SerializationHelperSql9.Serialize(_stream, invalidWrapper));
+ string expectedException = StringsHelper.GetString(Strings.SQL_CannotCreateNormalizer, invalidWrapper.Field2.GetType().FullName);
+
+ Assert.Equal(expectedException, ex.Message);
+ }
+
+ ///
+ /// Attempts to serialize a struct containing non-primitive value types.
+ /// Verifies that this fails.
+ ///
+ [Fact]
+ public void CannotSerializeNonPrimitiveType()
+ {
+ InvalidIntPtrAndByteWrapperStruct invalidWrapper = new()
+ {
+ Field1 = 1,
+ Field2 = IntPtr.Zero
+ };
+
+ var ex = Assert.Throws(() => SerializationHelperSql9.Serialize(_stream, invalidWrapper));
+ string expectedException = StringsHelper.GetString(Strings.SQL_CannotCreateNormalizer, invalidWrapper.Field2.GetType().FullName);
+
+ Assert.Equal(expectedException, ex.Message);
+ }
+
+ ///
+ /// Serializes an object, verifies the value and the size of the object, then roundtrips it and verifies the result is identical.
+ ///
+ /// Object to serialize.
+ /// Expected serialization output.
+ private void RoundtripType(object inputValue, byte[] expectedValue)
+ {
+ int typeSize = SerializationHelperSql9.SizeInBytes(inputValue.GetType());
+ int objectSize = SerializationHelperSql9.SizeInBytes(inputValue);
+ int maxTypeSize = SerializationHelperSql9.GetUdtMaxLength(inputValue.GetType());
+
+ SerializationHelperSql9.Serialize(_stream, inputValue);
+ _stream.Seek(0, SeekOrigin.Begin);
+ object readPrimitive = SerializationHelperSql9.Deserialize(_stream, inputValue.GetType());
+
+ // For native formatting, the type size, the object size and the maximum object size will always be identical
+ Assert.Equal(typeSize, objectSize);
+ Assert.Equal(expectedValue.Length, typeSize);
+ Assert.Equal(typeSize, maxTypeSize);
+
+ Assert.Equal(expectedValue, _stream.ToArray());
+ Assert.Equal(inputValue, readPrimitive);
+ }
+}
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/SerializedTypes.cs b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/SerializedTypes.cs
new file mode 100644
index 0000000000..a02c213e01
--- /dev/null
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/SerializedTypes.cs
@@ -0,0 +1,335 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.SqlServer.Server;
+using System;
+using System.Data.SqlTypes;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace Microsoft.Data.SqlClient.UnitTests.UdtSerialization.SerializedTypes;
+
+// Simple cases: a struct containing one of the designated primitive types
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct BoolWrapperStruct { public bool Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct ByteWrapperStruct { public byte Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SByteWrapperStruct { public sbyte Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct UShortWrapperStruct { public ushort Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct ShortWrapperStruct { public short Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct UIntWrapperStruct { public uint Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct IntWrapperStruct { public int Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct ULongWrapperStruct { public ulong Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct LongWrapperStruct { public long Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct FloatWrapperStruct { public float Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct DoubleWrapperStruct { public double Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlByteWrapperStruct { public SqlByte Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlInt16WrapperStruct { public SqlInt16 Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlInt32WrapperStruct { public SqlInt32 Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlInt64WrapperStruct { public SqlInt64 Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlBooleanWrapperStruct { public SqlBoolean Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlSingleWrapperStruct { public SqlSingle Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlDoubleWrapperStruct { public SqlDouble Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlDateTimeWrapperStruct { public SqlDateTime Field1; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct SqlMoneyWrapperStruct { public SqlMoney Field1; }
+
+
+// Success case: a class containing one of the designated primitive types
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal class BoolWrapperClass { public bool Field1; }
+
+// Success case: a struct containing one designated primitive type and one nested struct
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedBoolWrapperStruct { public bool Field1; public BoolWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedByteWrapperStruct { public byte Field1; public ByteWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSByteWrapperStruct { public sbyte Field1; public SByteWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedUShortWrapperStruct { public ushort Field1; public UShortWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedShortWrapperStruct { public short Field1; public ShortWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedUIntWrapperStruct { public uint Field1; public UIntWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedIntWrapperStruct { public int Field1; public IntWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedULongWrapperStruct { public ulong Field1; public ULongWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedLongWrapperStruct { public long Field1; public LongWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedFloatWrapperStruct { public float Field1; public FloatWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedDoubleWrapperStruct { public double Field1; public DoubleWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlByteWrapperStruct { public SqlByte Field1; public SqlByteWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlInt16WrapperStruct { public SqlInt16 Field1; public SqlInt16WrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlInt32WrapperStruct { public SqlInt32 Field1; public SqlInt32WrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlInt64WrapperStruct { public SqlInt64 Field1; public SqlInt64WrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlBooleanWrapperStruct { public SqlBoolean Field1; public SqlBooleanWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlSingleWrapperStruct { public SqlSingle Field1; public SqlSingleWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlDoubleWrapperStruct { public SqlDouble Field1; public SqlDoubleWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlDateTimeWrapperStruct { public SqlDateTime Field1; public SqlDateTimeWrapperStruct Field2; }
+
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct NestedSqlMoneyWrapperStruct { public SqlMoney Field1; public SqlMoneyWrapperStruct Field2; }
+
+
+// Success case: a class containing one designated primitive type and a nested struct
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal class NestedBoolWrapperClass { public bool Field1; public BoolWrapperStruct Field2; }
+
+// Failure case: a struct or a class containing one designated primitive type and a nested class
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal class InvalidNestedBoolWrapperClass { public bool Field1; public BoolWrapperClass? Field2; }
+
+// Failure case: a struct or a class containing a field which is not a designated primitive type
+[SqlUserDefinedType(Format.Native)]
+[StructLayout(LayoutKind.Sequential)]
+internal struct InvalidIntPtrAndByteWrapperStruct { public byte Field1; public IntPtr Field2; }
+
+// Success case: a struct or a class implementing IBinarySerialize which would not otherwise be serializable
+internal interface IFormattingProgress
+{
+ bool ParameterlessConstructorInvoked { get; }
+ bool ReadInvoked { get; }
+ bool WriteInvoked { get; }
+}
+
+[SqlUserDefinedType(Format.UserDefined, MaxByteSize = 11)]
+internal struct UserDefinedFormattedStruct : IBinarySerialize, IFormattingProgress, IEquatable
+{
+ public IntPtr Field1;
+ public bool ParameterlessConstructorInvoked { get; }
+ public bool ReadInvoked { get; private set; }
+ public bool WriteInvoked { get; private set; }
+
+ public UserDefinedFormattedStruct()
+ {
+ ParameterlessConstructorInvoked = true;
+ }
+
+ public UserDefinedFormattedStruct(IntPtr field1)
+ {
+ Field1 = field1;
+ }
+
+ public void Read(BinaryReader r)
+ {
+ Field1 = IntPtr.Size switch
+ {
+ sizeof(uint) => (IntPtr)r.ReadUInt32(),
+ sizeof(ulong) => (IntPtr)r.ReadUInt64(),
+ _ => throw new Exception("Invalid IntPtr size")
+ };
+
+ ReadInvoked = true;
+ }
+
+ public void Write(BinaryWriter w)
+ {
+ if (IntPtr.Size == sizeof(uint))
+ {
+ w.Write((uint)Field1);
+ }
+ else if (IntPtr.Size == sizeof(ulong))
+ {
+ w.Write((ulong)Field1);
+ }
+ else
+ {
+ throw new Exception("Invalid IntPtr size");
+ }
+
+ WriteInvoked = true;
+ }
+
+ public bool Equals(UserDefinedFormattedStruct other)
+ => other.Field1 == Field1;
+}
+
+[SqlUserDefinedType(Format.UserDefined, MaxByteSize = 11)]
+internal class UserDefinedFormattedClass : IBinarySerialize, IFormattingProgress, IEquatable
+{
+ public IntPtr Field1;
+ public bool ParameterlessConstructorInvoked { get; }
+ public bool ReadInvoked { get; private set; }
+ public bool WriteInvoked { get; private set; }
+
+ public UserDefinedFormattedClass()
+ {
+ ParameterlessConstructorInvoked = true;
+ }
+
+ public UserDefinedFormattedClass(IntPtr field1)
+ {
+ Field1 = field1;
+ }
+
+ public void Read(BinaryReader r)
+ {
+ Field1 = IntPtr.Size switch
+ {
+ sizeof(uint) => (IntPtr)r.ReadUInt32(),
+ sizeof(ulong) => (IntPtr)r.ReadUInt64(),
+ _ => throw new Exception("Invalid IntPtr size")
+ };
+
+ ReadInvoked = true;
+ }
+
+ public void Write(BinaryWriter w)
+ {
+ if (IntPtr.Size == sizeof(uint))
+ {
+ w.Write((uint)Field1);
+ }
+ else if (IntPtr.Size == sizeof(ulong))
+ {
+ w.Write((ulong)Field1);
+ }
+ else
+ {
+ throw new Exception("Invalid IntPtr size");
+ }
+
+ WriteInvoked = true;
+ }
+
+ public bool Equals(UserDefinedFormattedClass? other)
+ => other is not null && other.Field1 == Field1;
+}
+
+// Failure cases: type does not have a public constructor, does not implement IBinarySerialize, does not have a SqlUserDefinedType attribute,
+// or has a SqlUserDefinedType attribute with a Format of Unknown.
+
+[SqlUserDefinedType(Format.UserDefined)]
+internal class UserDefinedMissingPublicConstructor : IBinarySerialize
+{
+ public UserDefinedMissingPublicConstructor(bool _) { }
+
+ public void Read(BinaryReader r) { }
+
+ public void Write(BinaryWriter w) { }
+}
+
+[SqlUserDefinedType(Format.UserDefined)]
+internal class UserDefinedDoesNotImplementIBinarySerialize
+{
+ public UserDefinedDoesNotImplementIBinarySerialize() { }
+}
+
+internal class ClassMissingSqlUserDefinedTypeAttribute
+{
+}
+
+[SqlUserDefinedType(Format.Unknown)]
+internal class UnknownFormattedClass
+{
+}
diff --git a/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/UserDefinedSerializationTest.cs b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/UserDefinedSerializationTest.cs
new file mode 100644
index 0000000000..da3f47f5ee
--- /dev/null
+++ b/src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft/Data/SqlClient/UdtSerialization/UserDefinedSerializationTest.cs
@@ -0,0 +1,121 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.Data.SqlClient.Server;
+using Microsoft.Data.SqlClient.UnitTests.UdtSerialization.SerializedTypes;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using Xunit;
+
+namespace Microsoft.Data.SqlClient.UnitTests.UdtSerialization;
+
+///
+/// Tests the user-defined UDT serialization method. Verifies that custom types round-trip.
+///
+public sealed class UserDefinedSerializationTest : IDisposable
+{
+ private readonly MemoryStream _stream;
+
+ ///
+ /// Initializes the MemoryStream used for all tests in this class.
+ ///
+ public UserDefinedSerializationTest()
+ {
+ _stream = new MemoryStream();
+ }
+
+ void IDisposable.Dispose()
+ {
+ _stream.Dispose();
+ }
+
+ ///
+ /// Attempts to serialize and deserialize an instance of a struct with a user-defined serialization method.
+ ///
+ ///
+ [Fact]
+ public void CanSerializeStruct()
+ => RoundtripType(new UserDefinedFormattedStruct((IntPtr)0x12345678));
+
+ ///
+ /// Attempts to serialize and deserialize an instance of a class with a user-defined serialization method.
+ ///
+ ///
+ [Fact]
+ public void CanSerializeClass()
+ => RoundtripType(new UserDefinedFormattedClass((IntPtr)0x12345678));
+
+ ///
+ /// Attempts to deserialize an instance of a type with a user-defined serialization method but without a public
+ /// parameterless constructor. Verifies that this fails.
+ ///
+ [Fact]
+ public void RequiresPublicParameterlessConstructor()
+ {
+ SerializationHelperSql9.Serialize(_stream, new UserDefinedMissingPublicConstructor(true));
+ _stream.Seek(0, SeekOrigin.Begin);
+
+ Assert.Throws(
+ () => SerializationHelperSql9.Deserialize(_stream, typeof(UserDefinedMissingPublicConstructor)));
+ }
+
+ ///
+ /// Attempts to deserialize an instance of a type with a user-defined serialization method but which does not,
+ /// implement IBinarySerialize. Verifies that this fails.
+ ///
+ [Fact]
+ public void RequiresIBinarySerializeImplementation()
+ {
+ Assert.Throws(
+ () => SerializationHelperSql9.Serialize(_stream, new UserDefinedDoesNotImplementIBinarySerialize()));
+ }
+
+ private void RoundtripType(T userObject)
+ where T : IFormattingProgress
+ {
+ int typeSize = SerializationHelperSql9.SizeInBytes(userObject.GetType());
+ int objectSize = SerializationHelperSql9.SizeInBytes(userObject);
+ int maxTypeSize = SerializationHelperSql9.GetUdtMaxLength(userObject.GetType());
+
+ SerializationHelperSql9.Serialize(_stream, userObject);
+ _stream.Seek(0, SeekOrigin.Begin);
+ byte[] serializedValue = _stream.ToArray();
+ T readInstance = (T)SerializationHelperSql9.Deserialize(_stream, userObject.GetType());
+
+ // If this is a struct, it will have been copied by value and the write to WriteInvoked will have been made
+ // to another copy of our object
+ if (!typeof(T).IsValueType)
+ {
+ Assert.True(userObject.WriteInvoked);
+ }
+
+ Assert.Equal(IntPtr.Size, typeSize);
+ Assert.Equal(IntPtr.Size, objectSize);
+ Assert.Equal(11, maxTypeSize);
+
+ Assert.Equal(IntPtr.Size, serializedValue.Length);
+ if (IntPtr.Size == 8)
+ {
+ Assert.Equal([0x78, 0x56, 0x34, 0x12, 0x00, 0x00, 0x00, 0x00], serializedValue);
+ }
+ else if (IntPtr.Size == 4)
+ {
+ Assert.Equal([0x78, 0x56, 0x34, 0x12], serializedValue);
+ }
+ else
+ {
+ Assert.Fail("Invalid IntPtr size.");
+ }
+
+ // In .NET Framework, Activator.CreateInstance does not invoke a struct's parameterless constructor
+#if NET
+ Assert.NotEqual(userObject.ParameterlessConstructorInvoked, readInstance.ParameterlessConstructorInvoked);
+ Assert.True(readInstance.ParameterlessConstructorInvoked);
+#endif
+ Assert.True(readInstance.ReadInvoked);
+
+ Assert.Equal(userObject, readInstance);
+ }
+}