fix(mocks): skip inaccessible internal accessors when mocking Azure.Response

TUnit.Mocks.SourceGenerator.Tests/MockGeneratorTests.cs

@@ -656,6 +656,43 @@ void M()
         return VerifyGeneratorOutput(source, [externalRef]);
     }
 
+    // Regression for https://github.com/thomhurst/TUnit/issues/5455 — public virtual properties
+    // whose setters are individually inaccessible (internal/private) must emit getter-only overrides.
+    // `Reason` is the control: `protected internal set` is reachable via the mock's inheritance, so
+    // its setter must still be emitted.
+    [Test]
+    public Task Partial_Mock_Omits_Inaccessible_Property_Setters()
+    {
+        var externalSource = """
+            namespace ExternalLib
+            {
+                public class ExternalResponse
+                {
+                    public virtual int StatusCode { get; internal set; }
+                    public virtual bool IsSuccess { get; private set; }
+                    public virtual string Reason { get; protected internal set; } = "";
+                }
+            }
+            """;
+
+        var externalRef = CreateExternalAssemblyReference(externalSource);
+
+        var source = """
+            using TUnit.Mocks;
+            using ExternalLib;
+
+            public class TestUsage
+            {
+                void M()
+                {
+                    var mock = Mock.Of<ExternalResponse>();
+                }
+            }
+            """;
+
+        return VerifyGeneratorOutput(source, [externalRef]);
+    }
+
     [Test]
     public Task Partial_Mock_Filters_Members_With_Internal_Signature_Types()
     {

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

@@ -0,0 +1,117 @@
+// <auto-generated/>
+#nullable enable
+
+namespace TUnit.Mocks.Generated.ExternalLib
+{
+    file sealed class ExternalResponseMockImpl : global::ExternalLib.ExternalResponse, global::TUnit.Mocks.IRaisable, global::TUnit.Mocks.IMockObject
+    {
+        private readonly global::TUnit.Mocks.MockEngine<global::ExternalLib.ExternalResponse> _engine;
+
+        [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+        global::TUnit.Mocks.IMock? global::TUnit.Mocks.IMockObject.MockWrapper { get; set; }
+
+        internal ExternalResponseMockImpl(global::TUnit.Mocks.MockEngine<global::ExternalLib.ExternalResponse> engine) : base()
+        {
+            _engine = engine;
+        }
+
+        public override int StatusCode
+        {
+            get
+            {
+                if (_engine.TryHandleCallWithReturn<int>(0, "get_StatusCode", global::System.Array.Empty<object?>(), default, out var __result))
+                {
+                    return __result;
+                }
+                return base.StatusCode;
+            }
+        }
+
+        public override bool IsSuccess
+        {
+            get
+            {
+                if (_engine.TryHandleCallWithReturn<bool>(1, "get_IsSuccess", global::System.Array.Empty<object?>(), default, out var __result))
+                {
+                    return __result;
+                }
+                return base.IsSuccess;
+            }
+        }
+
+        public override string Reason
+        {
+            get
+            {
+                if (_engine.TryHandleCallWithReturn<string>(2, "get_Reason", global::System.Array.Empty<object?>(), "", out var __result))
+                {
+                    return __result;
+                }
+                return base.Reason;
+            }
+            set
+            {
+                if (!_engine.TryHandleCall(3, "set_Reason", new object?[] { value }))
+                {
+                    base.Reason = value;
+                }
+            }
+        }
+
+        [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 static class ExternalResponsePartialMockFactory
+    {
+        [global::System.Runtime.CompilerServices.ModuleInitializer]
+        internal static void Register()
+        {
+            global::TUnit.Mocks.MockRegistry.RegisterFactory<global::ExternalLib.ExternalResponse>(Create);
+        }
+
+        private static global::TUnit.Mocks.Mock<global::ExternalLib.ExternalResponse> Create(global::TUnit.Mocks.MockBehavior behavior, object[] constructorArgs)
+        {
+            var engine = new global::TUnit.Mocks.MockEngine<global::ExternalLib.ExternalResponse>(behavior);
+            var impl = new ExternalResponseMockImpl(engine);
+            engine.Raisable = impl;
+            var mock = new global::TUnit.Mocks.Mock<global::ExternalLib.ExternalResponse>(impl, engine);
+            return mock;
+        }
+    }
+}
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#nullable enable
+
+namespace TUnit.Mocks.Generated
+{
+    public static class ExternalLib_ExternalResponse_MockMemberExtensions
+    {
+        extension(global::TUnit.Mocks.Mock<global::ExternalLib.ExternalResponse> mock)
+        {
+            public global::TUnit.Mocks.PropertyMockCall<int> StatusCode
+                => new(global::TUnit.Mocks.MockRegistry.GetEngine(mock), 0, 0, "StatusCode", true, false);
+
+            public global::TUnit.Mocks.PropertyMockCall<bool> IsSuccess
+                => new(global::TUnit.Mocks.MockRegistry.GetEngine(mock), 1, 0, "IsSuccess", true, false);
+
+            public global::TUnit.Mocks.PropertyMockCall<string> Reason
+                => new(global::TUnit.Mocks.MockRegistry.GetEngine(mock), 2, 3, "Reason", true, true);
+        }
+    }
+}
+
+
+// ===== FILE SEPARATOR =====
+
+// <auto-generated/>
+#nullable enable
+
+namespace TUnit.Mocks.Generated;

TUnit.Mocks.SourceGenerator/Discovery/MemberDiscovery.cs

@@ -74,13 +74,13 @@ public static (EquatableArray<MockMemberModel> Methods, EquatableArray<MockMembe
                         {
                             if (existingIndex.HasValue)
                             {
-                                MergePropertyAccessors(properties, existingIndex.Value, property, ref memberIdCounter);
+                                MergePropertyAccessors(properties, existingIndex.Value, property, ref memberIdCounter, compilationAssembly);
                             }
                         }
                         else
                         {
                             seenProperties[key] = properties.Count;
-                            properties.Add(CreatePropertyModel(property, ref memberIdCounter, explicitInterfaceName, interfaceFqn));
+                            properties.Add(CreatePropertyModel(property, ref memberIdCounter, explicitInterfaceName, interfaceFqn, compilationAssembly));
                         }
                         break;
                     }
@@ -93,13 +93,13 @@ public static (EquatableArray<MockMemberModel> Methods, EquatableArray<MockMembe
                         {
                             if (existingIndex.HasValue)
                             {
-                                MergePropertyAccessors(properties, existingIndex.Value, indexer, ref memberIdCounter);
+                                MergePropertyAccessors(properties, existingIndex.Value, indexer, ref memberIdCounter, compilationAssembly);
                             }
                         }
                         else
                         {
                             seenProperties[key] = properties.Count;
-                            properties.Add(CreateIndexerModel(indexer, ref memberIdCounter, explicitInterfaceName, interfaceFqn));
+                            properties.Add(CreateIndexerModel(indexer, ref memberIdCounter, explicitInterfaceName, interfaceFqn, compilationAssembly));
                         }
                         break;
                     }
@@ -179,13 +179,13 @@ public static (EquatableArray<MockMemberModel> Methods, EquatableArray<MockMembe
                             {
                                 if (existingIndex.HasValue)
                                 {
-                                    MergePropertyAccessors(properties, existingIndex.Value, property, ref memberIdCounter);
+                                    MergePropertyAccessors(properties, existingIndex.Value, property, ref memberIdCounter, compilationAssembly);
                                 }
                             }
                             else
                             {
                                 seenProperties[key] = properties.Count;
-                                properties.Add(CreatePropertyModel(property, ref memberIdCounter, null, declaringInterfaceName: interfaceFqn));
+                                properties.Add(CreatePropertyModel(property, ref memberIdCounter, null, declaringInterfaceName: interfaceFqn, compilationAssembly: compilationAssembly));
                             }
                             break;
                         }
@@ -198,13 +198,13 @@ public static (EquatableArray<MockMemberModel> Methods, EquatableArray<MockMembe
                             {
                                 if (existingIndex.HasValue)
                                 {
-                                    MergePropertyAccessors(properties, existingIndex.Value, indexer, ref memberIdCounter);
+                                    MergePropertyAccessors(properties, existingIndex.Value, indexer, ref memberIdCounter, compilationAssembly);
                                 }
                             }
                             else
                             {
                                 seenProperties[key] = properties.Count;
-                                properties.Add(CreateIndexerModel(indexer, ref memberIdCounter, null, declaringInterfaceName: interfaceFqn));
+                                properties.Add(CreateIndexerModel(indexer, ref memberIdCounter, null, declaringInterfaceName: interfaceFqn, compilationAssembly: compilationAssembly));
                             }
                             break;
                         }
@@ -292,13 +292,13 @@ private static void ProcessClassMembers(
                             {
                                 if (existingIndex.HasValue)
                                 {
-                                    MergePropertyAccessors(properties, existingIndex.Value, property, ref memberIdCounter);
+                                    MergePropertyAccessors(properties, existingIndex.Value, property, ref memberIdCounter, compilationAssembly);
                                 }
                             }
                             else
                             {
                                 seenProperties[key] = properties.Count;
-                                properties.Add(CreatePropertyModel(property, ref memberIdCounter, null));
+                                properties.Add(CreatePropertyModel(property, ref memberIdCounter, null, compilationAssembly: compilationAssembly));
                             }
                         }
                         else if (!seenProperties.ContainsKey(key))
@@ -318,13 +318,13 @@ private static void ProcessClassMembers(
                             {
                                 if (existingIndex.HasValue)
                                 {
-                                    MergePropertyAccessors(properties, existingIndex.Value, indexer, ref memberIdCounter);
+                                    MergePropertyAccessors(properties, existingIndex.Value, indexer, ref memberIdCounter, compilationAssembly);
                                 }
                             }
                             else
                             {
                                 seenProperties[key] = properties.Count;
-                                properties.Add(CreateIndexerModel(indexer, ref memberIdCounter, null));
+                                properties.Add(CreateIndexerModel(indexer, ref memberIdCounter, null, compilationAssembly: compilationAssembly));
                             }
                         }
                         else if (!seenProperties.ContainsKey(key))
@@ -362,9 +362,12 @@ private static void ProcessClassMembers(
     private static bool IsMemberAccessibleFromExternal(ISymbol member, IAssemblySymbol compilationAssembly, bool hasInternalAccess)
     {
         var accessibility = member.DeclaredAccessibility;
+        // Private: never accessible from another assembly (no InternalsVisibleTo equivalent for private).
         // ProtectedOrInternal (protected internal) is intentionally NOT blocked here:
         // the generated mock subclasses the target, so the protected part grants access.
         // ProtectedAndInternal (private protected) requires BOTH inheritance AND internal access.
+        if (accessibility == Accessibility.Private)
+            return false;
         if (accessibility is Accessibility.Internal or Accessibility.ProtectedAndInternal)
         {
             if (!hasInternalAccess)
@@ -376,7 +379,7 @@ private static bool IsMemberAccessibleFromExternal(ISymbol member, IAssemblySymb
 
     /// <summary>
     /// Full accessibility check for members where the containing assembly isn't pre-computed
-    /// (used by DiscoverConstructors).
+    /// (used by DiscoverConstructors and IsAccessorAccessible).
     /// </summary>
     private static bool IsMemberAccessible(ISymbol member, IAssemblySymbol? compilationAssembly)
     {
@@ -387,6 +390,9 @@ private static bool IsMemberAccessible(ISymbol member, IAssemblySymbol? compilat
             return true;
 
         var accessibility = member.DeclaredAccessibility;
+        // Private: never reachable cross-assembly (no InternalsVisibleTo equivalent for private).
+        if (accessibility == Accessibility.Private)
+            return false;
         if (accessibility is Accessibility.Internal or Accessibility.ProtectedAndInternal)
         {
             if (!memberAssembly.GivesAccessTo(compilationAssembly))
@@ -532,27 +538,38 @@ private static MockMemberModel CreateMethodModel(IMethodSymbol method, ref int m
     /// accessors so the generated class satisfies all interfaces.
     /// </summary>
     private static void MergePropertyAccessors(List<MockMemberModel> properties, int existingIndex,
-        IPropertySymbol newProperty, ref int memberIdCounter)
+        IPropertySymbol newProperty, ref int memberIdCounter, IAssemblySymbol? compilationAssembly = null)
     {
         var existing = properties[existingIndex];
-        var needsGetter = !existing.HasGetter && newProperty.GetMethod is not null;
-        var needsSetter = !existing.HasSetter && newProperty.SetMethod is not null;
+        var newGetterAccessible = IsAccessorAccessible(newProperty.GetMethod, compilationAssembly);
+        var newSetterAccessible = IsAccessorAccessible(newProperty.SetMethod, compilationAssembly);
+        var needsGetter = !existing.HasGetter && newGetterAccessible;
+        var needsSetter = !existing.HasSetter && newSetterAccessible;
 
         if (!needsGetter && !needsSetter) return;
 
         properties[existingIndex] = existing with
         {
-            HasGetter = existing.HasGetter || newProperty.GetMethod is not null,
-            HasSetter = existing.HasSetter || newProperty.SetMethod is not null,
+            HasGetter = existing.HasGetter || newGetterAccessible,
+            HasSetter = existing.HasSetter || newSetterAccessible,
             SetterMemberId = existing.HasSetter ? existing.SetterMemberId
-                : newProperty.SetMethod is not null ? memberIdCounter++ : existing.SetterMemberId
+                : newSetterAccessible ? memberIdCounter++ : existing.SetterMemberId
         };
     }
 
-    private static MockMemberModel CreatePropertyModel(IPropertySymbol property, ref int memberIdCounter, string? explicitInterfaceName, string? declaringInterfaceName = null)
+    /// <summary>
+    /// Returns true if the accessor exists AND is accessible from the compilation assembly.
+    /// Needed because e.g. `internal set` on an external type exists in the symbol but can't be overridden.
+    /// </summary>
+    private static bool IsAccessorAccessible(IMethodSymbol? accessor, IAssemblySymbol? compilationAssembly)
+        => accessor is not null && IsMemberAccessible(accessor, compilationAssembly);
+
+    private static MockMemberModel CreatePropertyModel(IPropertySymbol property, ref int memberIdCounter, string? explicitInterfaceName, string? declaringInterfaceName = null, IAssemblySymbol? compilationAssembly = null)
     {
+        var hasGetter = IsAccessorAccessible(property.GetMethod, compilationAssembly);
+        var hasSetter = IsAccessorAccessible(property.SetMethod, compilationAssembly);
         var getterId = memberIdCounter++;
-        var setterId = property.SetMethod is not null ? memberIdCounter++ : 0;
+        var setterId = hasSetter ? memberIdCounter++ : 0;
 
         return new MockMemberModel
         {
@@ -563,8 +580,8 @@ private static MockMemberModel CreatePropertyModel(IPropertySymbol property, ref
             IsVoid = false,
             IsAsync = false,
             IsProperty = true,
-            HasGetter = property.GetMethod is not null,
-            HasSetter = property.SetMethod is not null,
+            HasGetter = hasGetter,
+            HasSetter = hasSetter,
             SetterMemberId = setterId,
             ExplicitInterfaceName = explicitInterfaceName,
             DeclaringInterfaceName = declaringInterfaceName,
@@ -613,10 +630,12 @@ public static EquatableArray<MockConstructorModel> DiscoverConstructors(INamedTy
         return new EquatableArray<MockConstructorModel>(constructors.ToImmutableArray());
     }
 
-    private static MockMemberModel CreateIndexerModel(IPropertySymbol indexer, ref int memberIdCounter, string? explicitInterfaceName, string? declaringInterfaceName = null)
+    private static MockMemberModel CreateIndexerModel(IPropertySymbol indexer, ref int memberIdCounter, string? explicitInterfaceName, string? declaringInterfaceName = null, IAssemblySymbol? compilationAssembly = null)
     {
+        var hasGetter = IsAccessorAccessible(indexer.GetMethod, compilationAssembly);
+        var hasSetter = IsAccessorAccessible(indexer.SetMethod, compilationAssembly);
         var getterId = memberIdCounter++;
-        var setterId = indexer.SetMethod is not null ? memberIdCounter++ : 0;
+        var setterId = hasSetter ? memberIdCounter++ : 0;
 
         return new MockMemberModel
         {
@@ -629,8 +648,8 @@ private static MockMemberModel CreateIndexerModel(IPropertySymbol indexer, ref i
             IsAsync = false,
             IsProperty = true,
             IsIndexer = true,
-            HasGetter = indexer.GetMethod is not null,
-            HasSetter = indexer.SetMethod is not null,
+            HasGetter = hasGetter,
+            HasSetter = hasSetter,
             Parameters = new EquatableArray<MockParameterModel>(
                 indexer.Parameters.Select(p => new MockParameterModel
                 {

TUnit.Mocks.Tests/Issue5455Tests.cs

@@ -0,0 +1,16 @@
+using Azure;
+
+namespace TUnit.Mocks.Tests;
+
+// Regression: https://github.com/thomhurst/TUnit/issues/5455
+// Azure.Response.IsError is `public virtual bool IsError { get; internal set; }` — the internal
+// setter is invisible to external assemblies, so the generated override must not emit it.
+public class Issue5455Tests
+{
+    [Test]
+    public void Mocking_Response_With_Internal_Setter_Compiles()
+    {
+        var mock = Mock.Of<Response>(MockBehavior.Strict);
+        _ = mock.Object;
+    }
+}