fix(mocks): resolve build errors when mocking Azure SDK clients

Directory.Packages.props

@@ -8,6 +8,8 @@
   <ItemGroup>
     <PackageVersion Include="Aspire.Hosting.AppHost" Version="13.2.1" />
     <PackageVersion Include="Aspire.Hosting.Testing" Version="13.2.1" />
+    <PackageVersion Include="Azure.Data.Tables" Version="12.11.0" />
+    <PackageVersion Include="Azure.Storage.Blobs" Version="12.27.0" />
     <PackageVersion Include="AutoFixture" Version="4.18.1" />
     <PackageVersion Include="BenchmarkDotNet" Version="0.15.8" />
     <PackageVersion Include="BenchmarkDotNet.Annotations" Version="0.15.8" />

TUnit.Mocks.SourceGenerator/Builders/MockImplBuilder.cs

@@ -569,7 +569,7 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
             writer.AppendLine("return;");
             writer.DecreaseIndent();
             writer.AppendLine("}");
-            writer.AppendLine($"base.{method.Name}({argPassList});");
+            writer.AppendLine($"base.{method.Name}{GetTypeParameterList(method)}({argPassList});");
         }
         else if (method.IsVoid && method.IsAsync)
         {
@@ -589,7 +589,7 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
             }
             writer.DecreaseIndent();
             writer.AppendLine("}");
-            writer.AppendLine($"return base.{method.Name}({argPassList});");
+            writer.AppendLine($"return base.{method.Name}{GetTypeParameterList(method)}({argPassList});");
         }
         else if (method.IsAsync)
         {
@@ -619,7 +619,7 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
             }
             writer.DecreaseIndent();
             writer.AppendLine("}");
-            writer.AppendLine($"return base.{method.Name}({argPassList});");
+            writer.AppendLine($"return base.{method.Name}{GetTypeParameterList(method)}({argPassList});");
         }
         else if (method.IsRefStructReturn)
         {
@@ -638,7 +638,7 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
             }
             writer.DecreaseIndent();
             writer.AppendLine("}");
-            writer.AppendLine($"return base.{method.Name}({argPassList});");
+            writer.AppendLine($"return base.{method.Name}{GetTypeParameterList(method)}({argPassList});");
         }
         else if (method.IsReturnTypeStaticAbstractInterface)
         {
@@ -650,7 +650,7 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
             writer.AppendLine("return __result;");
             writer.DecreaseIndent();
             writer.AppendLine("}");
-            writer.AppendLine($"return base.{method.Name}({argPassList});");
+            writer.AppendLine($"return base.{method.Name}{GetTypeParameterList(method)}({argPassList});");
         }
         else
         {
@@ -662,7 +662,7 @@ private static void GeneratePartialMethodBody(CodeWriter writer, MockMemberModel
             writer.AppendLine("return __result;");
             writer.DecreaseIndent();
             writer.AppendLine("}");
-            writer.AppendLine($"return base.{method.Name}({argPassList});");
+            writer.AppendLine($"return base.{method.Name}{GetTypeParameterList(method)}({argPassList});");
         }
     }
 

TUnit.Mocks.SourceGenerator/Builders/MockMembersBuilder.cs

@@ -41,8 +41,14 @@ public static string Build(MockTypeModel model)
             {
                 bool firstMember = true;
 
+                // Pre-compute which methods need their `out` parameters kept in the extension
+                // signature to avoid CS0111 collisions. A method needs disambiguation when
+                // some other method on the model shares the same name AND the same
+                // matchable-parameter signature (i.e. parameters excluding out).
+                var methodsWithDisambiguation = ApplyOutDisambiguation(model.Methods);
+
                 // Methods
-                foreach (var method in model.Methods)
+                foreach (var method in methodsWithDisambiguation)
                 {
                     if (!firstMember) writer.AppendLine();
                     firstMember = false;
@@ -84,6 +90,20 @@ public static string Build(MockTypeModel model)
         return writer.ToString();
     }
 
+    private static void EmitOutParamDefaults(CodeWriter writer, MockMemberModel method)
+    {
+        if (!method.KeepOutParamsInExtensionSignature) return;
+        // Out params are assigned `default!` because the extension method never actually invokes
+        // the mocked method — it only *configures* a setup. The out value is never observed by
+        // caller code: this setup-configuration call returns a MockMethodCall, not the mocked
+        // result. For reference types this suppresses the CS8625 nullable warning on an unused
+        // assignment that exists solely to satisfy the `out` contract.
+        foreach (var op in method.Parameters.Where(p => p.Direction == ParameterDirection.Out))
+        {
+            writer.AppendLine($"{op.Name} = default!;");
+        }
+    }
+
     private static bool ShouldGenerateTypedWrapper(MockMemberModel method, bool hasEvents)
     {
         if (method.IsGenericMethod) return false;
@@ -577,6 +597,54 @@ private static void GenerateMemberMethod(CodeWriter writer, MockMemberModel meth
         }
     }
 
+    /// <summary>
+    /// Returns the input methods, with <see cref="MockMemberModel.KeepOutParamsInExtensionSignature"/>
+    /// set to <c>true</c> on any method whose generated extension method would otherwise collide with
+    /// another overload. Methods are grouped by (name, type-arity, matchable-parameter signature);
+    /// any group with more than one entry causes its <c>out</c>-bearing members to be flagged.
+    /// The matchable-parameter signature includes parameter direction (ref/in/by-value) so that
+    /// overloads differing only by direction (e.g. <c>Foo(int)</c> vs <c>Foo(ref int)</c>) are not
+    /// treated as collisions.
+    /// </summary>
+    private static IEnumerable<MockMemberModel> ApplyOutDisambiguation(EquatableArray<MockMemberModel> methods)
+    {
+        var flagged = new HashSet<int>();
+        var byKey = new Dictionary<string, List<MockMemberModel>>(System.StringComparer.Ordinal);
+        foreach (var m in methods)
+        {
+            var matchable = string.Join(",", m.Parameters
+                .Where(p => p.Direction != ParameterDirection.Out)
+                .Select(p => $"{p.Direction}:{p.FullyQualifiedType}"));
+            var typeArity = m.TypeParameters.Length;
+            var key = $"{m.Name}`{typeArity}({matchable})";
+            if (!byKey.TryGetValue(key, out var list))
+            {
+                list = new List<MockMemberModel>();
+                byKey[key] = list;
+            }
+            list.Add(m);
+        }
+        foreach (var group in byKey.Values)
+        {
+            if (group.Count < 2) continue;
+            foreach (var m in group)
+            {
+                if (m.Parameters.Any(p => p.Direction == ParameterDirection.Out))
+                {
+                    flagged.Add(m.MemberId);
+                }
+            }
+        }
+
+        if (flagged.Count == 0)
+        {
+            return methods;
+        }
+        return methods.Select(m => flagged.Contains(m.MemberId)
+            ? m with { KeepOutParamsInExtensionSignature = true }
+            : m);
+    }
+
     private static (bool UseTypedWrapper, string ReturnType, string SetupReturnType) GetReturnTypeInfo(
         MockMemberModel method, MockTypeModel model, string safeName)
     {
@@ -633,6 +701,8 @@ private static void EmitMemberMethodBody(CodeWriter writer, MockMemberModel meth
 
         using (writer.Block($"public static {returnType} {safeMemberName}{typeParams}({fullParamList}){constraints}"))
         {
+            EmitOutParamDefaults(writer, method);
+
             // Build matchers array
             var matchableParams = includeRefStructArgs
                 ? method.Parameters.Where(p => p.Direction != ParameterDirection.Out).ToList()
@@ -717,7 +787,16 @@ private static void EmitSingleFuncOverload(CodeWriter writer, MockMemberModel me
         for (int i = 0; i < method.Parameters.Length; i++)
         {
             var p = method.Parameters[i];
-            if (p.Direction == ParameterDirection.Out) continue;
+            if (p.Direction == ParameterDirection.Out)
+            {
+                // Keep out params only when needed to disambiguate colliding overloads.
+                // Callers of the disambiguated overload must write `out _` at the call site.
+                if (method.KeepOutParamsInExtensionSignature)
+                {
+                    paramParts.Add($"out {p.FullyQualifiedType} {p.Name}");
+                }
+                continue;
+            }
 
             if (funcIndices.Contains(i))
             {
@@ -757,6 +836,8 @@ private static void EmitSingleFuncOverload(CodeWriter writer, MockMemberModel me
 
         using (writer.Block($"public static {returnType} {safeMemberName}{typeParams}({fullParamList}){constraints}"))
         {
+            EmitOutParamDefaults(writer, method);
+
             // Convert Func params to Arg<T> via implicit conversion
             foreach (var idx in funcIndices.OrderBy(i => i))
             {
@@ -876,7 +957,19 @@ private static string GetArgParameterList(MockMemberModel method, bool includeRe
         var parts = new List<string>();
         foreach (var p in method.Parameters)
         {
-            if (p.Direction == ParameterDirection.Out) continue;
+            if (p.Direction == ParameterDirection.Out)
+            {
+                // Normally out params are omitted from the extension signature so callers
+                // don't have to write `out _`. But when another overload of this method has
+                // the same matchable-parameter signature (e.g. GenerateSasUri(perms, expires)
+                // vs GenerateSasUri(perms, expires, out string)), we MUST keep the out param
+                // in the signature, otherwise CS0111 fires on the generated extensions.
+                if (method.KeepOutParamsInExtensionSignature)
+                {
+                    parts.Add($"out {p.FullyQualifiedType} {p.Name}");
+                }
+                continue;
+            }
             if (p.IsRefStruct)
             {
                 if (includeRefStructArgs)

TUnit.Mocks.SourceGenerator/Models/MockMemberModel.cs

@@ -45,6 +45,19 @@ internal sealed record MockMemberModel : IEquatable<MockMemberModel>
     /// </summary>
     public bool IsReturnTypeStaticAbstractInterface { get; init; }
 
+    /// <summary>
+    /// True when this method's <c>out</c> parameters must be kept in the generated extension
+    /// method signature to avoid CS0111 collisions with a sibling overload that shares the same
+    /// matchable-parameter signature (e.g. <c>BlobClient.GenerateSasUri(perms, expires)</c> vs
+    /// <c>GenerateSasUri(perms, expires, out string stringToSign)</c>). When true, callers must
+    /// pass <c>out _</c> at the call site for the disambiguated overload.
+    /// Computed transiently inside <see cref="Builders.MockMembersBuilder.Build"/> by examining
+    /// the full method set; never set on models flowing through the incremental pipeline.
+    /// Excluded from <see cref="Equals(MockMemberModel?)"/> / <see cref="GetHashCode"/> because
+    /// it is a derived per-build flag, not part of model identity.
+    /// </summary>
+    public bool KeepOutParamsInExtensionSignature { get; init; }
+
     /// <summary>
     /// For methods returning ReadOnlySpan&lt;T&gt; or Span&lt;T&gt;, the fully qualified element type.
     /// Null for non-span return types. Used to support configurable span return values via array conversion.

TUnit.Mocks.Tests/Issue5434Tests.cs

@@ -0,0 +1,49 @@
+using Azure.Data.Tables;
+using Azure.Storage.Blobs;
+using Azure.Storage.Sas;
+
+namespace TUnit.Mocks.Tests;
+
+// Reproduction and regression tests for https://github.com/thomhurst/TUnit/issues/5434
+// BlobClient: CS0111 duplicate GenerateSasUri / GenerateUserDelegationSasUri members in generated extensions.
+// TableClient: CS0411 type inference failures for generic methods (GetEntity<T>, GetEntityAsync<T>,
+// GetEntityIfExists<T>, GetEntityIfExistsAsync<T>, Query<T>, QueryAsync<T>) in generated impl factory.
+public class Issue5434Tests
+{
+    [Test]
+    public void Can_Mock_BlobClient()
+    {
+        var mock = Mock.Of<BlobClient>(MockBehavior.Strict);
+        _ = mock.Object;
+    }
+
+    [Test]
+    public void Can_Mock_TableClient()
+    {
+        var mock = Mock.Of<TableClient>(MockBehavior.Strict);
+        _ = mock.Object;
+    }
+
+    // Exercises the disambiguated overload that keeps `out string stringToSign` in its
+    // signature to distinguish it from GenerateSasUri(perms, expires). This call would not
+    // compile if `keepOutParams` disambiguation regressed.
+    [Test]
+    public void Can_Configure_BlobClient_GenerateSasUri_OutOverload()
+    {
+        var mock = Mock.Of<BlobClient>(MockBehavior.Loose);
+        _ = mock.GenerateSasUri(Arg.Any<BlobSasPermissions>(), Arg.Any<System.DateTimeOffset>(), out _);
+    }
+
+    // Exercises the generic-return-type override path. This would not compile if
+    // the base.GetEntity(...) call in the generated override was missing the <T> type argument.
+    [Test]
+    public void Can_Configure_TableClient_GetEntity_Generic()
+    {
+        var mock = Mock.Of<TableClient>(MockBehavior.Loose);
+        _ = mock.GetEntity<TableEntity>(
+            Arg.Any<string>(),
+            Arg.Any<string>(),
+            Arg.Any<System.Collections.Generic.IEnumerable<string>>(),
+            Arg.Any<System.Threading.CancellationToken>());
+    }
+}

TUnit.Mocks.Tests/TUnit.Mocks.Tests.csproj

@@ -9,6 +9,8 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Azure.Data.Tables" />
+    <PackageReference Include="Azure.Storage.Blobs" />
     <ProjectReference Include="..\TUnit.Mocks\TUnit.Mocks.csproj" />
     <ProjectReference Include="..\TUnit.Mocks.Assertions\TUnit.Mocks.Assertions.csproj" />