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thomhurst merged 2 commits into from
Feb 25, 2026
Merged

feat(mocks): handle ref struct parameters and return types #4999

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71f1123
feat(mocks): handle ref struct parameters and return types gracefully
thomhurst Feb 25, 2026
2775de0
fix: address review feedback for ref struct support
thomhurst Feb 25, 2026
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26 changes: 26 additions & 0 deletions TUnit.Mocks.SourceGenerator.Tests/MockGeneratorTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -242,6 +242,32 @@ void M()
return VerifyGeneratorOutput(source);
}

[Test]
public Task Interface_With_RefStruct_Parameters()
{
var source = """
using System;
using TUnit.Mocks;

public interface IBufferProcessor
{
void Process(ReadOnlySpan<byte> data);
int Parse(ReadOnlySpan<char> text);
string GetName();
}

public class TestUsage
{
void M()
{
var mock = Mock.Of<IBufferProcessor>();
}
}
""";

return VerifyGeneratorOutput(source);
}

[Test]
public Task Interface_With_Mixed_Members()
{
Expand Down
93 changes: 93 additions & 0 deletions TUnit.Mocks.SourceGenerator.Tests/Snapshots/Interface_With_RefStruct_Parameters.verified.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,93 @@
// <auto-generated/>
#nullable enable

namespace TUnit.Mocks.Generated
{
internal static class IBufferProcessor_MockFactory
{
[global::System.Runtime.CompilerServices.ModuleInitializer]
internal static void Register()
{
global::TUnit.Mocks.Mock.RegisterFactory<global::IBufferProcessor>(Create);
}

private static global::TUnit.Mocks.Mock<global::IBufferProcessor> Create(global::TUnit.Mocks.MockBehavior behavior)
{
var engine = new global::TUnit.Mocks.MockEngine<global::IBufferProcessor>(behavior);
var impl = new IBufferProcessor_MockImpl(engine);
engine.Raisable = impl;
var mock = new global::TUnit.Mocks.Mock<global::IBufferProcessor>(impl, engine);
return mock;
}
}
}


// ===== FILE SEPARATOR =====

// <auto-generated/>
#nullable enable

namespace TUnit.Mocks.Generated
{
internal sealed class IBufferProcessor_MockImpl : global::IBufferProcessor, global::TUnit.Mocks.IRaisable
{
private readonly global::TUnit.Mocks.MockEngine<global::IBufferProcessor> _engine;

internal IBufferProcessor_MockImpl(global::TUnit.Mocks.MockEngine<global::IBufferProcessor> engine)
{
_engine = engine;
}

public void Process(global::System.ReadOnlySpan<byte> data)
{
_engine.HandleCall(0, "Process", global::System.Array.Empty<object?>());
}

public int Parse(global::System.ReadOnlySpan<char> text)
{
return _engine.HandleCallWithReturn<int>(1, "Parse", global::System.Array.Empty<object?>(), default);
}

public string GetName()
{
return _engine.HandleCallWithReturn<string>(2, "GetName", global::System.Array.Empty<object?>(), "");
}

[global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
public void RaiseEvent(string eventName, object? args)
{
throw new global::System.InvalidOperationException($"No event named '{eventName}' exists on this mock.");
}
}
}


// ===== FILE SEPARATOR =====

// <auto-generated/>
#nullable enable

namespace TUnit.Mocks.Generated
{
public static class IBufferProcessor_MockMemberExtensions
{
public static global::TUnit.Mocks.VoidMockMethodCall Process(this global::TUnit.Mocks.Mock<global::IBufferProcessor> mock)
{
var matchers = global::System.Array.Empty<global::TUnit.Mocks.Arguments.IArgumentMatcher>();
return new global::TUnit.Mocks.VoidMockMethodCall(mock.Engine, 0, "Process", matchers);
}

public static global::TUnit.Mocks.MockMethodCall<int> Parse(this global::TUnit.Mocks.Mock<global::IBufferProcessor> mock)
{
var matchers = global::System.Array.Empty<global::TUnit.Mocks.Arguments.IArgumentMatcher>();
return new global::TUnit.Mocks.MockMethodCall<int>(mock.Engine, 1, "Parse", matchers);
}

public static global::TUnit.Mocks.MockMethodCall<string> GetName(this global::TUnit.Mocks.Mock<global::IBufferProcessor> mock)
{
var matchers = global::System.Array.Empty<global::TUnit.Mocks.Arguments.IArgumentMatcher>();
return new global::TUnit.Mocks.MockMethodCall<string>(mock.Engine, 2, "GetName", matchers);
}
}
}
130 changes: 120 additions & 10 deletions TUnit.Mocks.SourceGenerator/Builders/MockImplBuilder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -238,6 +238,17 @@ private static void GenerateWrapMethodBody(CodeWriter writer, MockMemberModel me
writer.AppendLine("}");
writer.AppendLine($"return _wrappedInstance.{method.Name}({argPassList});");
}
else if (method.IsRefStructReturn)
{
writer.AppendLine($"if (_engine.TryHandleCall({method.MemberId}, \"{method.Name}\", {argsArray}))");
writer.AppendLine("{");
writer.IncreaseIndent();
EmitOutRefReadback(writer, method);
writer.AppendLine("return default;");
writer.DecreaseIndent();
writer.AppendLine("}");
writer.AppendLine($"return _wrappedInstance.{method.Name}({argPassList});");
}
else
{
writer.AppendLine($"if (_engine.TryHandleCallWithReturn<{method.ReturnType}>({method.MemberId}, \"{method.Name}\", {argsArray}, {method.SmartDefault}, out var __result))");
Expand All @@ -259,7 +270,31 @@ private static void GenerateWrapProperty(CodeWriter writer, MockMemberModel prop

if (prop.HasGetter)
{
if (prop.IsAbstractMember)
if (prop.IsRefStructReturn)
{
if (prop.IsAbstractMember)
{
writer.AppendLine("get");
writer.OpenBrace();
writer.AppendLine($"_engine.HandleCall({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>());");
writer.AppendLine("return default;");
writer.CloseBrace();
}
else
{
writer.AppendLine("get");
writer.OpenBrace();
writer.AppendLine($"if (_engine.TryHandleCall({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>()))");
writer.AppendLine("{");
writer.IncreaseIndent();
writer.AppendLine("return default;");
writer.DecreaseIndent();
writer.AppendLine("}");
writer.AppendLine($"return _wrappedInstance.{prop.Name};");
writer.CloseBrace();
}
}
else if (prop.IsAbstractMember)
{
writer.AppendLine($"get => _engine.HandleCallWithReturn<{prop.ReturnType}>({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>(), {prop.SmartDefault});");
}
Expand All @@ -280,15 +315,19 @@ private static void GenerateWrapProperty(CodeWriter writer, MockMemberModel prop

if (prop.HasSetter)
{
var setterArgs = prop.IsRefStructReturn
? "global::System.Array.Empty<object?>()"
: "new object?[] { value }";

if (prop.IsAbstractMember)
{
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", new object?[] {{ value }});");
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", {setterArgs});");
}
else
{
writer.AppendLine("set");
writer.OpenBrace();
writer.AppendLine($"if (!_engine.TryHandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", new object?[] {{ value }}))");
writer.AppendLine($"if (!_engine.TryHandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", {setterArgs}))");
writer.AppendLine("{");
writer.IncreaseIndent();
writer.AppendLine($"_wrappedInstance.{prop.Name} = value;");
Expand Down Expand Up @@ -475,6 +514,18 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
writer.AppendLine("}");
writer.AppendLine($"return base.{method.Name}({argPassList});");
}
else if (method.IsRefStructReturn)
{
// synchronous method returning ref struct — use void dispatch, fall back to base
writer.AppendLine($"if (_engine.TryHandleCall({method.MemberId}, \"{method.Name}\", {argsArray}))");
writer.AppendLine("{");
writer.IncreaseIndent();
EmitOutRefReadback(writer, method);
writer.AppendLine("return default;");
writer.DecreaseIndent();
writer.AppendLine("}");
writer.AppendLine($"return base.{method.Name}({argPassList});");
}
else
{
// synchronous method with return value
Expand Down Expand Up @@ -566,6 +617,15 @@ private static void GenerateEngineDispatchBody(CodeWriter writer, MockMemberMode
}
}
}
else if (method.IsRefStructReturn)
{
// Synchronous method returning a ref struct — can't use HandleCallWithReturn<T> because
// ref structs can't be generic type arguments. Use void dispatch for call tracking,
// callbacks, and throws. Return default (e.g. ReadOnlySpan<byte>.Empty).
writer.AppendLine($"_engine.HandleCall({method.MemberId}, \"{method.Name}\", {argsArray});");
EmitOutRefReadback(writer, method);
writer.AppendLine("return default;");
}
else
{
// Synchronous method with return value — need to read back out/ref before returning
Expand All @@ -589,12 +649,32 @@ private static void GenerateInterfaceProperty(CodeWriter writer, MockMemberModel

if (prop.HasGetter)
{
writer.AppendLine($"get => _engine.HandleCallWithReturn<{prop.ReturnType}>({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>(), {prop.SmartDefault});");
if (prop.IsRefStructReturn)
{
// ref struct property — can't use HandleCallWithReturn<T>, use void dispatch + return default
writer.AppendLine("get");
writer.OpenBrace();
writer.AppendLine($"_engine.HandleCall({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>());");
writer.AppendLine("return default;");
writer.CloseBrace();
}
else
{
writer.AppendLine($"get => _engine.HandleCallWithReturn<{prop.ReturnType}>({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>(), {prop.SmartDefault});");
}
}

if (prop.HasSetter)
{
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", new object?[] {{ value }});");
if (prop.IsRefStructReturn)
{
// ref struct property — can't box value, use empty args
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", global::System.Array.Empty<object?>());");
}
else
{
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", new object?[] {{ value }});");
}
}

writer.CloseBrace();
Expand All @@ -608,7 +688,31 @@ private static void GeneratePartialProperty(CodeWriter writer, MockMemberModel p

if (prop.HasGetter)
{
if (prop.IsAbstractMember)
if (prop.IsRefStructReturn)
{
if (prop.IsAbstractMember)
{
writer.AppendLine("get");
writer.OpenBrace();
writer.AppendLine($"_engine.HandleCall({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>());");
writer.AppendLine("return default;");
writer.CloseBrace();
}
else
{
writer.AppendLine("get");
writer.OpenBrace();
writer.AppendLine($"if (_engine.TryHandleCall({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>()))");
writer.AppendLine("{");
writer.IncreaseIndent();
writer.AppendLine("return default;");
writer.DecreaseIndent();
writer.AppendLine("}");
writer.AppendLine($"return base.{prop.Name};");
writer.CloseBrace();
}
}
else if (prop.IsAbstractMember)
{
writer.AppendLine($"get => _engine.HandleCallWithReturn<{prop.ReturnType}>({prop.MemberId}, \"get_{prop.Name}\", global::System.Array.Empty<object?>(), {prop.SmartDefault});");
}
Expand All @@ -630,16 +734,20 @@ private static void GeneratePartialProperty(CodeWriter writer, MockMemberModel p

if (prop.HasSetter)
{
var setterArgs = prop.IsRefStructReturn
? "global::System.Array.Empty<object?>()"
: "new object?[] { value }";

if (prop.IsAbstractMember)
{
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", new object?[] {{ value }});");
writer.AppendLine($"set => _engine.HandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", {setterArgs});");
}
else
{
// Virtual property setter: try engine, fall back to base
writer.AppendLine("set");
writer.OpenBrace();
writer.AppendLine($"if (!_engine.TryHandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", new object?[] {{ value }}))");
writer.AppendLine($"if (!_engine.TryHandleCall({prop.SetterMemberId}, \"set_{prop.Name}\", {setterArgs}))");
writer.AppendLine("{");
writer.IncreaseIndent();
writer.AppendLine($"base.{prop.Name} = value;");
Expand Down Expand Up @@ -838,6 +946,7 @@ private static void EmitOutRefReadback(CodeWriter writer, MockMemberModel method
for (int i = 0; i < method.Parameters.Length; i++)
{
var p = method.Parameters[i];
if (p.IsRefStruct) continue; // ref structs can't be cast from object
if (p.Direction == ParameterDirection.Out || p.Direction == ParameterDirection.Ref)
{
writer.AppendLine($"if (__outRef.TryGetValue({i}, out var __v{i})) {p.Name} = ({p.FullyQualifiedType})__v{i}!;");
Expand All @@ -848,8 +957,9 @@ private static void EmitOutRefReadback(CodeWriter writer, MockMemberModel method

private static string GetArgsArrayExpression(MockMemberModel method)
{
// Only include non-out parameters in args array
var matchableParams = method.Parameters.Where(p => p.Direction != ParameterDirection.Out).ToList();
// Only include non-out, non-ref-struct parameters in args array
// (ref structs cannot be boxed into object?[])
var matchableParams = method.Parameters.Where(p => p.Direction != ParameterDirection.Out && !p.IsRefStruct).ToList();
if (matchableParams.Count == 0) return "global::System.Array.Empty<object?>()";
var args = string.Join(", ", matchableParams.Select(p => p.Name));
return $"new object?[] {{ {args} }}";
Expand Down
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