Fix S2094 FP: Should not raise for messages

analyzers/its/expected/akka.net/S2094-Akka-netstandard2.0.json

@@ -23,24 +23,6 @@
       "Message": "Remove this empty class, write its code or make it an \u0022interface\u0022.",
       "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/akka.net/src/core/Akka/IO/Inet.cs#L229",
       "Location": "Line 229 Position 31-43"
-    },
-    {
-      "Id": "S2094",
-      "Message": "Remove this empty class, write its code or make it an \u0022interface\u0022.",
-      "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/akka.net/src/core/Akka/IO/Tcp.cs#L738",
-      "Location": "Line 738 Position 22-27"
-    },
-    {
-      "Id": "S2094",
-      "Message": "Remove this empty class, write its code or make it an \u0022interface\u0022.",
-      "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/akka.net/src/core/Akka/Routing/Listeners.cs#L37",
-      "Location": "Line 37 Position 27-42"
-    },
-    {
-      "Id": "S2094",
-      "Message": "Remove this empty class, write its code or make it an \u0022interface\u0022.",
-      "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/akka.net/src/core/Akka/Routing/RouterMsg.cs#L31",
-      "Location": "Line 31 Position 27-50"
     }
   ]
 }

analyzers/src/SonarAnalyzer.Common/Rules/ClassShouldNotBeEmptyBase.cs

@@ -31,6 +31,8 @@ public abstract class ClassShouldNotBeEmptyBase<TSyntaxKind, TDeclarationSyntax>
         KnownType.System_Attribute,
         KnownType.System_Exception);
 
+    private static readonly IEnumerable<string> IgnoredSuffixes = ["Command", "Event", "Message"];
+
     protected abstract bool IsEmptyAndNotPartial(SyntaxNode node);
     protected abstract TDeclarationSyntax GetIfHasDeclaredBaseClassOrInterface(SyntaxNode node);
     protected abstract bool HasInterfaceOrGenericBaseClass(TDeclarationSyntax declaration);
@@ -51,13 +53,17 @@ protected override void Initialize(SonarAnalysisContext context) =>
                     && IsEmptyAndNotPartial(c.Node)
                     && !HasAnyAttribute(c.Node)
                     && !HasConditionalCompilationDirectives(c.Node)
+                    && !ShouldIgnoreBecauseOfName(identifier)
                     && !ShouldIgnoreBecauseOfBaseClassOrInterface(c.Node, c.SemanticModel))
                 {
                     c.ReportIssue(Diagnostic.Create(Rule, identifier.GetLocation(), DeclarationTypeKeyword(c.Node)));
                 }
             },
             Language.SyntaxKind.ClassAndRecordClassDeclarations);
 
+    private static bool ShouldIgnoreBecauseOfName(SyntaxToken identifier) =>
+        IgnoredSuffixes.Any(identifier.ValueText.EndsWith);
+
     private bool ShouldIgnoreBecauseOfBaseClassOrInterface(SyntaxNode node, SemanticModel model) =>
         GetIfHasDeclaredBaseClassOrInterface(node) is { } declaration
         && (HasInterfaceOrGenericBaseClass(declaration) || ShouldIgnoreType(declaration, model));

analyzers/tests/SonarAnalyzer.Test/TestCases/ClassShouldNotBeEmpty.cs

@@ -126,4 +126,16 @@ class ImplementsMarker: IMarker { }          // Compliant - implements a marker
     struct EmptyStruct { }                       // Compliant - this rule only deals with classes
 
     enum EmptyEnum { }                           // Compliant - this rule only deals with classes
+
+    class SomeCommand { }                        // Compliant, ignored because of the suffix
+    class SomeEvent { }                          // Compliant, ignored because of the suffix
+    class SomeMessage { }                        // Compliant, ignored because of the suffix
+    class Some_Command { }                       // Compliant, ignored because of the suffix
+    class Someevent { }                          // Noncompliant
+    class SOMEMESSAGE { }                        // Noncompliant
+    class SomeCommandHandler { }                 // Noncompliant
+    class MessageHandler { }                     // Noncompliant
+    class Command { }                            // Compliant, ignored because of the suffix
+    class Event { }                              // Compliant, ignored because of the suffix
+    class Message { }                            // Compliant, ignored because of the suffix
 }