Add the PosInfoMoq2015 rule to check the return type of the Protected…

…() setup methods (fixes #38).

PosInformatique.Moq.Analyzers.sln

@@ -52,6 +52,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Compilation", "Compilation"
 		docs\Compilation\PosInfoMoq2012.md = docs\Compilation\PosInfoMoq2012.md
 		docs\Compilation\PosInfoMoq2013.md = docs\Compilation\PosInfoMoq2013.md
 		docs\Compilation\PosInfoMoq2014.md = docs\Compilation\PosInfoMoq2014.md
+		docs\Compilation\PosInfoMoq2015.md = docs\Compilation\PosInfoMoq2015.md
 	EndProjectSection
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Moq.Analyzers.Sandbox", "tests\Moq.Analyzers.Sandbox\Moq.Analyzers.Sandbox.csproj", "{07F970A1-1477-4D4C-B233-C9B4DA6E3AD6}"

README.md

@@ -54,6 +54,7 @@ All the rules of this category should not be disabled (or changed their severity
 | [PosInfoMoq2012: The delegate in the argument of the `Returns()` method must return a value with same type of the mocked method.](docs/Compilation/PosInfoMoq2012.md) | The lambda expression, anonymous method or method in the argument of the `Returns()` must return return a value of the same type as the mocked method or property. |
 | [PosInfoMoq2013: The delegate in the argument of the `Returns()`/`ReturnsAsync()` method must have the same parameter types of the mocked method/property.](docs/Compilation/PosInfoMoq2013.md) | The lambda expression, anonymous method or method in the argument of the `Returns()`/`ReturnsAsync()` must have the same arguments type of the mocked method or property. |
 | [PosInfoMoq2014: The `Callback()` delegate expression must not return a value.](docs/Compilation/PosInfoMoq2014.md) | The `Callback()` delegate expression must not return a value. |
+| [PosInfoMoq2014: PosInfoMoq2015: The `Protected().Setup()` method must match the return type of the mocked method](docs/Compilation/PosInfoMoq2015.md) | The method setup with `Protected().Setup()` must match the return type of the mocked method. |
 
 
 

docs/Compilation/PosInfoMoq2006.md

@@ -24,7 +24,7 @@ and must be overridable (`virtual`, `abstract` and `override`, but not `sealed`)
 public void Test()
 {
     var service = new Mock<Service>();
-    service.Protected().Setup("GetData")            // The GetData() is public and can be mocked with Protected() feature.
+    service.Protected().Setup("GetData")            // The GetData() is public and can't be mocked with Protected() feature.
         .Returns(10);
     service.Protected().Setup("NotExists")          // The NotExists() method does not exist.
         .Returns(10);

docs/Compilation/PosInfoMoq2015.md

@@ -0,0 +1,50 @@
+# PosInfoMoq2015: The `Protected().Setup()` method must match the return type of the mocked method
+
+| Property                            | Value																                         |
+|-------------------------------------|----------------------------------------------------------------------------------------------|
+| **Rule ID**                         | PosInfoMoq2015														                         |
+| **Title**                           | The `Protected().Setup()` method must match the return type of the mocked method.            |
+| **Category**                        | Compilation															                         |
+| **Default severity**				  | Error																                         |
+
+## Cause
+
+The method setup with `Protected().Setup()` must match the return type of the mocked method.
+
+## Rule description
+
+When using the `Protected().Setup()`, the return type of mocked method must match of the generic
+argument specified in the `Setup<T>()` method.
+
+```csharp
+[Fact]
+public void Test()
+{
+    var service = new Mock<Service>();
+    service.Protected().Setup<int>("GetData")       // OK.
+        .Returns(10);
+    service.Protected().Setup("GetData")            // Error: The GetData() return an int, Setup<int>() must be use.
+    service.Protected().Setup<int>("SendEmail")     // Error: The SendEmail() method does not return a value, the `int` generic argument must be remove.0
+        .Returns(10);
+    service.Protected().Setup<string>("GetData")    // Error: The GetData() return an int, Setup<int>() must be use.
+        .Returns("The data");
+}
+
+public abstract class Service
+{
+    protected abstract int GetData();
+
+    protected abstract void SendEmail();
+}
+```
+
+## How to fix violations
+
+To fix a violation of this rule, use the generic parameter of the `Setup<T>()` method if the protected mocked
+method return a value. Else do not specify a generic parameter for the `Setup<T>()` method of the protected mocked
+method does not return a value (`void`).
+
+## When to suppress warnings
+
+Do not suppress an error from this rule. If bypassed, the execution of the unit test will be failed with a `ArgumentException`
+thrown with the *"Can't set return value for void method xxx."* message.

src/Moq.Analyzers/AnalyzerReleases.Shipped.md

@@ -3,7 +3,8 @@
 ### New Rules
 Rule ID | Category | Severity | Notes
 --------|----------|----------|-------
-PosInfoMoq2014 | Compilation | Error | CallBackDelegateMustMatchMockedMethodAnalyzer, [Documentation](https://posinformatique.github.io/PosInformatique.Moq.Analyzers/docs/Compilation/PosInfoMoq2014.html)PosInfoMoq2013 | Compilation | Error | The delegate in the argument of the `Returns()`/`ReturnsAsync()` method must have the same parameter types of the mocked method/property.
+PosInfoMoq2014 | Compilation | Error | The `Callback()` delegate expression must not return a value.
+PosInfoMoq2015 | Compilation | Error | The `Protected().Setup()` method must match the return type of the mocked method.
 
 ## Release 1.10.0
 

src/Moq.Analyzers/Analyzers/SetupProtectedMustBeUsedWithProtectedOrInternalMembersAnalyzer.cs

@@ -15,7 +15,7 @@ namespace PosInformatique.Moq.Analyzers
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
     public class SetupProtectedMustBeUsedWithProtectedOrInternalMembersAnalyzer : DiagnosticAnalyzer
     {
-        private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(
+        private static readonly DiagnosticDescriptor SetupMustBeOnOverridableMethods = new DiagnosticDescriptor(
             "PosInfoMoq2006",
             "The Protected().Setup() method must be use with overridable protected or internal methods",
             "The Protected().Setup() method must be use with overridable protected or internal methods",
@@ -25,7 +25,17 @@ public class SetupProtectedMustBeUsedWithProtectedOrInternalMembersAnalyzer : Di
             description: "The Protected().Setup() method must be use with overridable protected or internal methods.",
             helpLinkUri: "https://posinformatique.github.io/PosInformatique.Moq.Analyzers/docs/Compilation/PosInfoMoq2006.html");
 
-        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
+        private static readonly DiagnosticDescriptor SetupReturnTypeMustMatch = new DiagnosticDescriptor(
+            "PosInfoMoq2015",
+            "The Protected().Setup() method must match the return type of the mocked method",
+            "The Protected().Setup() method must match the return type of the mocked method",
+            "Compilation",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true,
+            description: "The Protected().Setup() method must match the return type of the mocked method.",
+            helpLinkUri: "https://posinformatique.github.io/PosInformatique.Moq.Analyzers/docs/Compilation/PosInfoMoq2015.html");
+
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(SetupMustBeOnOverridableMethods, SetupReturnTypeMustMatch);
 
         public override void Initialize(AnalysisContext context)
         {
@@ -81,6 +91,8 @@ private static void Analyze(SyntaxNodeAnalysisContext context)
             }
 
             // Check if a method exists with the specified name
+            IMethodSymbol? methodMatch = null;
+
             foreach (var method in mockedType.GetAllMembers(methodName).OfType<IMethodSymbol>())
             {
                 if (!method.IsAbstract && !method.IsVirtual && !method.IsOverride)
@@ -95,23 +107,78 @@ private static void Analyze(SyntaxNodeAnalysisContext context)
 
                 if (method.DeclaredAccessibility == Accessibility.Protected)
                 {
-                    return;
+                    methodMatch = method;
+                    break;
                 }
 
                 if (method.DeclaredAccessibility == Accessibility.Internal)
                 {
-                    return;
+                    methodMatch = method;
+                    break;
                 }
 
                 if (method.DeclaredAccessibility == Accessibility.ProtectedOrInternal)
                 {
-                    return;
+                    methodMatch = method;
+                    break;
+                }
+            }
+
+            if (methodMatch is null)
+            {
+                // No method match, raise an error.
+                context.ReportDiagnostic(SetupMustBeOnOverridableMethods, literalExpression.GetLocation());
+                return;
+            }
+
+            // Else check the argument type of the Setup<T>() method and the method found.
+            var setupMethodSymbol = context.SemanticModel.GetSymbolInfo(invocationExpression, context.CancellationToken);
+
+            if (setupMethodSymbol.Symbol is not IMethodSymbol setupMethod)
+            {
+                return;
+            }
+
+            if (invocationExpression.Expression is not MemberAccessExpressionSyntax memberAccessExpressionSyntax)
+            {
+                return;
+            }
+
+            if (methodMatch.ReturnsVoid)
+            {
+                if (setupMethod.TypeArguments.Length > 0)
+                {
+                    if (memberAccessExpressionSyntax.Name is not GenericNameSyntax genericNameSyntax)
+                    {
+                        return;
+                    }
+
+                    // The method mocked is void and no generic arguments has been specified in the Setup<T>() method.
+                    context.ReportDiagnostic(SetupReturnTypeMustMatch, genericNameSyntax.TypeArgumentList.Arguments[0].GetLocation());
                 }
+
+                return;
+            }
+
+            if (setupMethod.TypeArguments.Length != 1)
+            {
+                // No generic type has been specified in the Setup<T>().
+                context.ReportDiagnostic(SetupReturnTypeMustMatch, memberAccessExpressionSyntax.Name.GetLocation());
+                return;
             }
 
-            // No returns method has been specified with Strict mode. Report the diagnostic issue.
-            var diagnostic = Diagnostic.Create(Rule, literalExpression.GetLocation());
-            context.ReportDiagnostic(diagnostic);
+            if (!SymbolEqualityComparer.Default.Equals(setupMethod.TypeArguments[0], methodMatch.ReturnType))
+            {
+                if (memberAccessExpressionSyntax.Name is not GenericNameSyntax genericNameSyntax)
+                {
+                    return;
+                }
+
+                // The method mocked return a type which does not match the argument type of the Setup<T>() method.
+                context.ReportDiagnostic(SetupReturnTypeMustMatch, genericNameSyntax.TypeArgumentList.Arguments[0].GetLocation());
+
+                return;
+            }
         }
     }
 }

src/Moq.Analyzers/Moq.Analyzers.csproj

@@ -20,6 +20,7 @@
       1.10.0
       - Add new rules:
         - PosInfoMoq2014: The delegate in the argument of the Returns() method must return a value with same type of the mocked method.
+        - PosInfoMoq2015: The Protected().Setup() method must match the return type of the mocked method.
 
       1.10.0
       - Add new rules: