Refactor code based on code review feedback

Extract helper methods IsActivityMethod, IsOrchestratorMethod, and ImplementsInterface to reduce code duplication. Move system assembly names to static readonly collections. Optimize LINQ chain in ScanReferencedAssemblies to use simple foreach loop.

Co-authored-by: YunchuWang <[email protected]>

Author: Copilot

src/Analyzers/Activities/FunctionNotFoundAnalyzer.cs

@@ -10,6 +10,8 @@
 
 namespace Microsoft.DurableTask.Analyzers.Activities;
 
+/// <summary>
+/// Analyzer that detects calls to non-existent activities and sub-orchestrations.
 /// <summary>
 /// Analyzer that detects calls to non-existent activities and sub-orchestrations.
 /// </summary>
@@ -26,6 +28,22 @@ public sealed class FunctionNotFoundAnalyzer : DiagnosticAnalyzer
     /// </summary>
     public const string SubOrchestrationNotFoundDiagnosticId = "DURABLE2004";
 
+    // System assemblies to skip when scanning referenced assemblies for performance
+    static readonly HashSet<string> SystemAssemblyNames =
+    [
+        "mscorlib",
+        "System",
+        "netstandard"
+    ];
+
+    static readonly string[] SystemAssemblyPrefixes =
+    [
+        "System.",
+        "Microsoft.CodeAnalysis",
+        "Microsoft.CSharp",
+        "Microsoft.VisualBasic"
+    ];
+
     static readonly LocalizableString ActivityNotFoundTitle = new LocalizableResourceString(nameof(Resources.ActivityNotFoundAnalyzerTitle), Resources.ResourceManager, typeof(Resources));
     static readonly LocalizableString ActivityNotFoundMessageFormat = new LocalizableResourceString(nameof(Resources.ActivityNotFoundAnalyzerMessageFormat), Resources.ResourceManager, typeof(Resources));
 
@@ -129,19 +147,13 @@ public override void Initialize(AnalysisContext context)
                     }
 
                     // Check for Activity defined via [ActivityTrigger]
-                    if (knownSymbols.ActivityTriggerAttribute != null &&
-                        methodSymbol.ContainsAttributeInAnyMethodArguments(knownSymbols.ActivityTriggerAttribute) &&
-                        knownSymbols.FunctionNameAttribute != null &&
-                        methodSymbol.TryGetSingleValueFromAttribute(knownSymbols.FunctionNameAttribute, out string functionName))
+                    if (IsActivityMethod(methodSymbol, knownSymbols, out string functionName))
                     {
                         activityNames.Add(functionName);
                     }
 
                     // Check for Orchestrator defined via [OrchestrationTrigger]
-                    if (knownSymbols.FunctionOrchestrationAttribute != null &&
-                        methodSymbol.ContainsAttributeInAnyMethodArguments(knownSymbols.FunctionOrchestrationAttribute) &&
-                        knownSymbols.FunctionNameAttribute != null &&
-                        methodSymbol.TryGetSingleValueFromAttribute(knownSymbols.FunctionNameAttribute, out string orchestratorFunctionName))
+                    if (IsOrchestratorMethod(methodSymbol, knownSymbols, out string orchestratorFunctionName))
                     {
                         orchestratorNames.Add(orchestratorFunctionName);
                     }
@@ -173,7 +185,7 @@ public override void Initialize(AnalysisContext context)
 
                     // Check for ITaskOrchestrator implementations (class-based orchestrators)
                     if (knownSymbols.TaskOrchestratorInterface != null &&
-                        classSymbol.AllInterfaces.Any(i => SymbolEqualityComparer.Default.Equals(i, knownSymbols.TaskOrchestratorInterface)))
+                        ImplementsInterface(classSymbol, knownSymbols.TaskOrchestratorInterface))
                     {
                         orchestratorNames.Add(classSymbol.Name);
                     }
@@ -281,6 +293,49 @@ public override void Initialize(AnalysisContext context)
         return constant.Value?.ToString();
     }
 
+    static bool IsActivityMethod(IMethodSymbol methodSymbol, KnownTypeSymbols knownSymbols, out string functionName)
+    {
+        functionName = string.Empty;
+
+        if (knownSymbols.ActivityTriggerAttribute == null ||
+            !methodSymbol.ContainsAttributeInAnyMethodArguments(knownSymbols.ActivityTriggerAttribute))
+        {
+            return false;
+        }
+
+        if (knownSymbols.FunctionNameAttribute == null ||
+            !methodSymbol.TryGetSingleValueFromAttribute(knownSymbols.FunctionNameAttribute, out functionName))
+        {
+            return false;
+        }
+
+        return true;
+    }
+
+    static bool IsOrchestratorMethod(IMethodSymbol methodSymbol, KnownTypeSymbols knownSymbols, out string functionName)
+    {
+        functionName = string.Empty;
+
+        if (knownSymbols.FunctionOrchestrationAttribute == null ||
+            !methodSymbol.ContainsAttributeInAnyMethodArguments(knownSymbols.FunctionOrchestrationAttribute))
+        {
+            return false;
+        }
+
+        if (knownSymbols.FunctionNameAttribute == null ||
+            !methodSymbol.TryGetSingleValueFromAttribute(knownSymbols.FunctionNameAttribute, out functionName))
+        {
+            return false;
+        }
+
+        return true;
+    }
+
+    static bool ImplementsInterface(INamedTypeSymbol typeSymbol, INamedTypeSymbol interfaceSymbol)
+    {
+        return typeSymbol.AllInterfaces.Any(i => SymbolEqualityComparer.Default.Equals(i, interfaceSymbol));
+    }
+
     static bool ClassOverridesMethod(INamedTypeSymbol classSymbol, IMethodSymbol methodToFind)
     {
         INamedTypeSymbol? baseType = classSymbol;
@@ -308,14 +363,21 @@ static void ScanReferencedAssemblies(
     {
         // Scan all referenced assemblies for activities and orchestrators
         // Skip system assemblies for performance
-        foreach (IAssemblySymbol assembly in compilation.References
-            .Select(r => compilation.GetAssemblyOrModuleSymbol(r))
-            .OfType<IAssemblySymbol>()
-            .Where(a => !IsSystemAssembly(a)))
+        foreach (MetadataReference reference in compilation.References)
         {
             cancellationToken.ThrowIfCancellationRequested();
 
-            // Get all types in the assembly
+            if (compilation.GetAssemblyOrModuleSymbol(reference) is not IAssemblySymbol assembly)
+            {
+                continue;
+            }
+
+            if (IsSystemAssembly(assembly))
+            {
+                continue;
+            }
+
+            // Scan this assembly
             ScanNamespaceForFunctions(
                 assembly.GlobalNamespace,
                 knownSymbols,
@@ -330,13 +392,21 @@ static bool IsSystemAssembly(IAssemblySymbol assembly)
     {
         // Skip well-known system assemblies to improve performance
         string assemblyName = assembly.Name;
-        return assemblyName == "mscorlib" ||
-               assemblyName == "System" ||
-               assemblyName == "netstandard" ||
-               assemblyName.StartsWith("System.", StringComparison.Ordinal) ||
-               assemblyName.StartsWith("Microsoft.CodeAnalysis", StringComparison.Ordinal) ||
-               assemblyName.StartsWith("Microsoft.CSharp", StringComparison.Ordinal) ||
-               assemblyName.StartsWith("Microsoft.VisualBasic", StringComparison.Ordinal);
+
+        if (SystemAssemblyNames.Contains(assemblyName))
+        {
+            return true;
+        }
+
+        foreach (string prefix in SystemAssemblyPrefixes)
+        {
+            if (assemblyName.StartsWith(prefix, StringComparison.Ordinal))
+            {
+                return true;
+            }
+        }
+
+        return false;
     }
 
     static void ScanNamespaceForFunctions(
@@ -365,7 +435,7 @@ static void ScanNamespaceForFunctions(
 
             // Check for ITaskOrchestrator implementations (class-based orchestrators)
             if (knownSymbols.TaskOrchestratorInterface != null &&
-                typeSymbol.AllInterfaces.Any(i => SymbolEqualityComparer.Default.Equals(i, knownSymbols.TaskOrchestratorInterface)))
+                ImplementsInterface(typeSymbol, knownSymbols.TaskOrchestratorInterface))
             {
                 orchestratorNames.Add(typeSymbol.Name);
             }
@@ -381,19 +451,13 @@ static void ScanNamespaceForFunctions(
                 }
 
                 // Check for Activity defined via [ActivityTrigger]
-                if (knownSymbols.ActivityTriggerAttribute != null &&
-                    methodSymbol.ContainsAttributeInAnyMethodArguments(knownSymbols.ActivityTriggerAttribute) &&
-                    knownSymbols.FunctionNameAttribute != null &&
-                    methodSymbol.TryGetSingleValueFromAttribute(knownSymbols.FunctionNameAttribute, out string functionName))
+                if (IsActivityMethod(methodSymbol, knownSymbols, out string functionName))
                 {
                     activityNames.Add(functionName);
                 }
 
                 // Check for Orchestrator defined via [OrchestrationTrigger]
-                if (knownSymbols.FunctionOrchestrationAttribute != null &&
-                    methodSymbol.ContainsAttributeInAnyMethodArguments(knownSymbols.FunctionOrchestrationAttribute) &&
-                    knownSymbols.FunctionNameAttribute != null &&
-                    methodSymbol.TryGetSingleValueFromAttribute(knownSymbols.FunctionNameAttribute, out string orchestratorFunctionName))
+                if (IsOrchestratorMethod(methodSymbol, knownSymbols, out string orchestratorFunctionName))
                 {
                     orchestratorNames.Add(orchestratorFunctionName);
                 }