fix(mocks): mocking a method with more params than Func/Action arity (#6254)

TUnit.Mocks.SourceGenerator.Tests/MockGeneratorTests.cs

@@ -1291,6 +1291,66 @@ void M()
         return VerifyGeneratorOutput(source);
     }
 
+    [Test]
+    public Task Method_With_More_Params_Than_Func_Action_Arity()
+    {
+        // Issue #6254: an async method with more parameters than the BCL Func<>/Action<> arity
+        // limit (16 inputs) must not emit typed Returns/ReturnsAsync/Callback/Throws overloads —
+        // doing so produced CS0305. The wrapper is still generated (for the untyped ReturnsAsync
+        // surface); only the parameter-typed convenience overloads are omitted.
+        var source = """
+            using System.Threading.Tasks;
+            using TUnit.Mocks;
+
+            public interface ILongMethodSignatures
+            {
+                Task SomeMethod(string _1, string _2, string _3, string _4, string _5,
+                    string _6, string _7, string _8, string _9, string _10,
+                    string _11, string _12, string _13, string _14, string _15,
+                    string _16, string _17, string _18, string _19, string _20);
+            }
+
+            public class TestUsage
+            {
+                void M()
+                {
+                    var mock = Mock.Of<ILongMethodSignatures>();
+                }
+            }
+            """;
+
+        return VerifyGeneratorOutput(source);
+    }
+
+    [Test]
+    public Task Returning_Async_Method_With_More_Params_Than_Func_Action_Arity()
+    {
+        // Issue #6254, returning-async (Task<T>) variant. This routes through the value-returning
+        // unified-class emit path (distinct from the void-Task path above), which has its own
+        // arity gate. At 17 params — one past the BCL Func<>/Action<> limit — the typed overloads
+        // must be omitted while the untyped Returns/ReturnsAsync surface is retained.
+        var source = """
+            using System.Threading.Tasks;
+            using TUnit.Mocks;
+
+            public interface ILongReturningSignature
+            {
+                Task<int> Sum(int _1, int _2, int _3, int _4, int _5, int _6, int _7, int _8, int _9,
+                    int _10, int _11, int _12, int _13, int _14, int _15, int _16, int _17);
+            }
+
+            public class TestUsage
+            {
+                void M()
+                {
+                    var mock = Mock.Of<ILongReturningSignature>();
+                }
+            }
+            """;
+
+        return VerifyGeneratorOutput(source);
+    }
+
     [Test]
     public Task GenerateMock_Attribute_With_Concrete_Class()
     {

TUnit.Mocks.SourceGenerator.Tests/Snapshots/Method_With_More_Params_Than_Func_Action_Arity.verified.txt

@@ -0,0 +1,259 @@
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+
+public sealed class ILongMethodSignaturesMock : global::TUnit.Mocks.Mock<global::ILongMethodSignatures>, global::ILongMethodSignatures
+{
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    internal ILongMethodSignaturesMock(global::ILongMethodSignatures mockObject, global::TUnit.Mocks.MockEngine<global::ILongMethodSignatures> engine)
+        : base(mockObject, engine) { }
+
+    global::System.Threading.Tasks.Task global::ILongMethodSignatures.SomeMethod(string _1, string _2, string _3, string _4, string _5, string _6, string _7, string _8, string _9, string _10, string _11, string _12, string _13, string _14, string _15, string _16, string _17, string _18, string _19, string _20) => Object.SomeMethod(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20);
+}
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+
+file sealed class ILongMethodSignaturesMockImpl : global::ILongMethodSignatures, global::TUnit.Mocks.IRaisable, global::TUnit.Mocks.IMockObject
+{
+    private readonly global::TUnit.Mocks.MockEngine<global::ILongMethodSignatures> _engine;
+
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    global::TUnit.Mocks.IMock? global::TUnit.Mocks.IMockObject.MockWrapper { get; set; }
+
+    internal ILongMethodSignaturesMockImpl(global::TUnit.Mocks.MockEngine<global::ILongMethodSignatures> engine)
+    {
+        _engine = engine;
+    }
+
+    public global::System.Threading.Tasks.Task SomeMethod(string _1, string _2, string _3, string _4, string _5, string _6, string _7, string _8, string _9, string _10, string _11, string _12, string _13, string _14, string _15, string _16, string _17, string _18, string _19, string _20)
+    {
+        try
+        {
+            _engine.HandleCall(0, "SomeMethod", new object?[] { _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20 });
+            if (global::TUnit.Mocks.Setup.RawReturnContext.TryConsume(out var __rawAsync))
+            {
+                if (__rawAsync is global::System.Threading.Tasks.Task __typedAsync) return __typedAsync;
+                throw new global::System.InvalidOperationException($"ReturnsAsync: expected global::System.Threading.Tasks.Task but got {__rawAsync?.GetType().Name ?? "null"}");
+            }
+            return global::System.Threading.Tasks.Task.CompletedTask;
+        }
+        catch (global::System.Exception __ex)
+        {
+            return global::System.Threading.Tasks.Task.FromException(__ex);
+        }
+    }
+
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    public void RaiseEvent(string eventName, object? args)
+    {
+        throw new global::System.InvalidOperationException($"No event named '{eventName}' exists on this mock.");
+    }
+}
+
+internal static class ILongMethodSignaturesMockFactory
+{
+    [global::System.Runtime.CompilerServices.ModuleInitializer]
+    internal static void Register()
+    {
+        global::TUnit.Mocks.MockRegistry.RegisterFactory<global::ILongMethodSignatures>(Create);
+    }
+
+    internal static global::TUnit.Mocks.Mock<global::ILongMethodSignatures> CreateAutoMock(global::TUnit.Mocks.MockBehavior behavior)
+    {
+        var engine = new global::TUnit.Mocks.MockEngine<global::ILongMethodSignatures>(behavior);
+        var impl = new ILongMethodSignaturesMockImpl(engine);
+        engine.Raisable = impl;
+        var mock = new ILongMethodSignaturesMock(impl, engine);
+        return mock;
+    }
+
+    internal static global::TUnit.Mocks.Mock<global::ILongMethodSignatures> Create(global::TUnit.Mocks.MockBehavior behavior, object[] constructorArgs)
+    {
+        if (constructorArgs.Length > 0) throw new global::System.ArgumentException($"Interface mock 'global::ILongMethodSignatures' does not support constructor arguments, but {constructorArgs.Length} were provided.");
+        var engine = new global::TUnit.Mocks.MockEngine<global::ILongMethodSignatures>(behavior);
+        var impl = new ILongMethodSignaturesMockImpl(engine);
+        engine.Raisable = impl;
+        var mock = new ILongMethodSignaturesMock(impl, engine);
+        return mock;
+    }
+}
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+
+public static class ILongMethodSignatures_MockMemberExtensions
+{
+    public static ILongMethodSignatures_SomeMethod_M0_MockCall SomeMethod(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock, global::TUnit.Mocks.Arguments.Arg<string> _1, global::TUnit.Mocks.Arguments.Arg<string> _2, global::TUnit.Mocks.Arguments.Arg<string> _3, global::TUnit.Mocks.Arguments.Arg<string> _4, global::TUnit.Mocks.Arguments.Arg<string> _5, global::TUnit.Mocks.Arguments.Arg<string> _6, global::TUnit.Mocks.Arguments.Arg<string> _7, global::TUnit.Mocks.Arguments.Arg<string> _8, global::TUnit.Mocks.Arguments.Arg<string> _9, global::TUnit.Mocks.Arguments.Arg<string> _10, global::TUnit.Mocks.Arguments.Arg<string> _11, global::TUnit.Mocks.Arguments.Arg<string> _12, global::TUnit.Mocks.Arguments.Arg<string> _13, global::TUnit.Mocks.Arguments.Arg<string> _14, global::TUnit.Mocks.Arguments.Arg<string> _15, global::TUnit.Mocks.Arguments.Arg<string> _16, global::TUnit.Mocks.Arguments.Arg<string> _17, global::TUnit.Mocks.Arguments.Arg<string> _18, global::TUnit.Mocks.Arguments.Arg<string> _19, global::TUnit.Mocks.Arguments.Arg<string> _20)
+    {
+        var matchers = new global::TUnit.Mocks.Arguments.IArgumentMatcher[] { _1.Matcher, _2.Matcher, _3.Matcher, _4.Matcher, _5.Matcher, _6.Matcher, _7.Matcher, _8.Matcher, _9.Matcher, _10.Matcher, _11.Matcher, _12.Matcher, _13.Matcher, _14.Matcher, _15.Matcher, _16.Matcher, _17.Matcher, _18.Matcher, _19.Matcher, _20.Matcher };
+        return new ILongMethodSignatures_SomeMethod_M0_MockCall(global::TUnit.Mocks.MockRegistry.GetEngine(mock), 0, "SomeMethod", matchers);
+    }
+
+    /// <summary>Configure the mock setup for <c>SomeMethod</c> with every argument matched as <c>Any&lt;T&gt;()</c>.</summary>
+    public static ILongMethodSignatures_SomeMethod_M0_MockCall SomeMethod(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock, global::TUnit.Mocks.Arguments.AnyArgs _)
+    {
+        var matchers = new global::TUnit.Mocks.Arguments.IArgumentMatcher[] { global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance, global::TUnit.Mocks.Matchers.AnyMatcher<string>.Instance };
+        return new ILongMethodSignatures_SomeMethod_M0_MockCall(global::TUnit.Mocks.MockRegistry.GetEngine(mock), 0, "SomeMethod", matchers);
+    }
+
+    #if NET9_0_OR_GREATER
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static void Reset(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock)
+        => global::TUnit.Mocks.Mock.Reset(mock);
+
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static void VerifyAll(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock)
+        => global::TUnit.Mocks.Mock.VerifyAll(mock);
+
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static void VerifyNoOtherCalls(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock)
+        => global::TUnit.Mocks.Mock.VerifyNoOtherCalls(mock);
+
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static void SetupAllProperties(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock)
+        => global::TUnit.Mocks.Mock.SetupAllProperties(mock);
+
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static global::TUnit.Mocks.Diagnostics.MockDiagnostics GetDiagnostics(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock)
+        => global::TUnit.Mocks.Mock.GetDiagnostics(mock);
+
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static void SetState(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock, string? stateName)
+        => global::TUnit.Mocks.Mock.SetState(mock, stateName);
+
+    [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+    public static void InState(this global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock, string stateName, global::System.Action<global::TUnit.Mocks.Mock<global::ILongMethodSignatures>> configure)
+        => global::TUnit.Mocks.Mock.InState(mock, stateName, configure);
+
+    extension(global::TUnit.Mocks.Mock<global::ILongMethodSignatures> mock)
+    {
+        [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+        public global::System.Collections.Generic.IReadOnlyList<global::TUnit.Mocks.Verification.CallRecord> Invocations => global::TUnit.Mocks.Mock.Invocations(mock);
+
+        [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+        public global::TUnit.Mocks.MockBehavior Behavior => global::TUnit.Mocks.Mock.Behavior(mock);
+
+        [global::System.Runtime.CompilerServices.OverloadResolutionPriority(-1)]
+        public global::TUnit.Mocks.IDefaultValueProvider? DefaultValueProvider
+        {
+            get => global::TUnit.Mocks.Mock.GetDefaultValueProvider(mock);
+            set => global::TUnit.Mocks.Mock.SetDefaultValueProvider(mock, value);
+        }
+    }
+    #endif
+}
+
+[global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+public sealed class ILongMethodSignatures_SomeMethod_M0_MockCall : global::TUnit.Mocks.Verification.ICallVerification
+{
+    private readonly global::TUnit.Mocks.IMockEngineAccess _engine;
+    private readonly int _memberId;
+    private readonly string _memberName;
+    private readonly global::TUnit.Mocks.Arguments.IArgumentMatcher[] _matchers;
+    private global::TUnit.Mocks.Setup.VoidMethodSetupBuilder? _builder;
+
+    internal ILongMethodSignatures_SomeMethod_M0_MockCall(global::TUnit.Mocks.IMockEngineAccess engine, int memberId, string memberName, global::TUnit.Mocks.Arguments.IArgumentMatcher[] matchers)
+    {
+        _engine = engine;
+        _memberId = memberId;
+        _memberName = memberName;
+        _matchers = matchers;
+        _ = EnsureSetup();
+    }
+
+    private global::TUnit.Mocks.Setup.VoidMethodSetupBuilder EnsureSetup()
+    {
+        var existing = global::System.Threading.Volatile.Read(ref _builder);
+        if (existing is not null) return existing;
+        return EnsureSetupSlow();
+    }
+
+    [global::System.Runtime.CompilerServices.MethodImpl(global::System.Runtime.CompilerServices.MethodImplOptions.NoInlining)]
+    private global::TUnit.Mocks.Setup.VoidMethodSetupBuilder EnsureSetupSlow()
+    {
+        var setup = new global::TUnit.Mocks.Setup.MethodSetup(_memberId, _matchers, _memberName);
+        var fresh = new global::TUnit.Mocks.Setup.VoidMethodSetupBuilder(setup);
+        var prev = global::System.Threading.Interlocked.CompareExchange(ref _builder, fresh, null);
+        if (prev is not null) return prev;
+        // AddSetup runs only on the CAS winner. Setup is sequential in practice,
+        // so a concurrent loser observing the builder before registration is benign.
+        _engine.AddSetup(setup);
+        return fresh;
+    }
+
+    /// <inheritdoc />
+    public ILongMethodSignatures_SomeMethod_M0_MockCall Returns() { EnsureSetup().Returns(); return this; }
+    /// <inheritdoc />
+    public ILongMethodSignatures_SomeMethod_M0_MockCall Throws<TException>() where TException : global::System.Exception, new() { EnsureSetup().Throws<TException>(); return this; }
+    /// <inheritdoc />
+    public ILongMethodSignatures_SomeMethod_M0_MockCall Throws(global::System.Exception exception) { EnsureSetup().Throws(exception); return this; }
+    /// <inheritdoc />
+    public ILongMethodSignatures_SomeMethod_M0_MockCall Callback(global::System.Action callback) { EnsureSetup().Callback(callback); return this; }
+    /// <inheritdoc />
+    public ILongMethodSignatures_SomeMethod_M0_MockCall TransitionsTo(string stateName) { EnsureSetup().TransitionsTo(stateName); return this; }
+    /// <inheritdoc />
+    public ILongMethodSignatures_SomeMethod_M0_MockCall Then() { EnsureSetup().Then(); return this; }
+
+    /// <summary>Return a pre-built Task directly (e.g., from a TaskCompletionSource).</summary>
+    public ILongMethodSignatures_SomeMethod_M0_MockCall ReturnsAsync(global::System.Threading.Tasks.Task task) { EnsureSetup().ReturnsRaw(task); return this; }
+    /// <summary>Return a pre-built Task from a factory, invoked on each call.</summary>
+    public ILongMethodSignatures_SomeMethod_M0_MockCall ReturnsAsync(global::System.Func<global::System.Threading.Tasks.Task> taskFactory) { EnsureSetup().ReturnsRaw(() => (object?)taskFactory()); return this; }
+
+    // ICallVerification
+    /// <inheritdoc />
+    public void WasCalled() => _engine.CreateVerification(_memberId, _memberName, _matchers).WasCalled();
+    /// <inheritdoc />
+    public void WasCalled(global::TUnit.Mocks.Times times) => _engine.CreateVerification(_memberId, _memberName, _matchers).WasCalled(times);
+    /// <inheritdoc />
+    public void WasCalled(global::TUnit.Mocks.Times times, string? message) => _engine.CreateVerification(_memberId, _memberName, _matchers).WasCalled(times, message);
+    /// <inheritdoc />
+    public void WasCalled(string? message) => _engine.CreateVerification(_memberId, _memberName, _matchers).WasCalled(message);
+    /// <inheritdoc />
+    public void WasNeverCalled() => _engine.CreateVerification(_memberId, _memberName, _matchers).WasNeverCalled();
+    /// <inheritdoc />
+    public void WasNeverCalled(string? message) => _engine.CreateVerification(_memberId, _memberName, _matchers).WasNeverCalled(message);
+}
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+
+namespace TUnit.Mocks
+{
+    public static class ILongMethodSignatures_MockStaticExtension
+    {
+        extension(global::ILongMethodSignatures _)
+        {
+            public static global::ILongMethodSignaturesMock Mock()
+            {
+                return (global::ILongMethodSignaturesMock)global::ILongMethodSignaturesMockFactory.CreateAutoMock(global::TUnit.Mocks.Mock.DefaultBehavior);
+            }
+
+            public static global::ILongMethodSignaturesMock Mock(global::TUnit.Mocks.MockBehavior behavior)
+            {
+                return (global::ILongMethodSignaturesMock)global::ILongMethodSignaturesMockFactory.CreateAutoMock(behavior);
+            }
+        }
+    }
+}
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+
+namespace TUnit.Mocks.Generated;