Implement test code analyzer

ScriptCoreGenerator/StyleChecker.cs

@@ -0,0 +1,63 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Text;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace ScriptCoreGenerator;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public class StyleChecker : DiagnosticAnalyzer
+{
+    public const string DiagnosticId = "MakeConst";
+
+    private static readonly LocalizableString Title =
+        new LocalizableResourceString(nameof(Strings.AnalyzerTitle), Strings.ResourceManager, typeof(Strings));
+    private static readonly LocalizableString MessageFormat =
+        new LocalizableResourceString(nameof(Strings.AnalyzerMessageFormat), Strings.ResourceManager, typeof(Strings));
+    private static readonly LocalizableString Description =
+        new LocalizableResourceString(nameof(Strings.AnalyzerDescription), Strings.ResourceManager, typeof(Strings));
+
+    private const string Category = "Usage";
+
+    private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat,
+        Category, DiagnosticSeverity.Warning, isEnabledByDefault: true, description: Description);
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
+
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+        
+        context.RegisterSyntaxNodeAction(AnalyzeNode, SyntaxKind.LocalDeclarationStatement);
+    }
+
+    private void AnalyzeNode(SyntaxNodeAnalysisContext context)
+    {
+        var localDeclaration = (LocalDeclarationStatementSyntax)context.Node;
+
+        if (localDeclaration.Modifiers.Any(SyntaxKind.ConstKeyword))
+        {
+            return;
+        }
+
+        // Perform data flow analysis on the local declaration.
+        DataFlowAnalysis dataFlowAnalysis = context.SemanticModel.AnalyzeDataFlow(localDeclaration);
+
+        // Retrieve the local symbol for each variable in the local declaration
+        // and ensure that it is not written outside of the data flow analysis region.
+        VariableDeclaratorSyntax variable = localDeclaration.Declaration.Variables.Single();
+        ISymbol variableSymbol = context.SemanticModel.GetDeclaredSymbol(variable, context.CancellationToken);
+        if (dataFlowAnalysis.WrittenOutside.Contains(variableSymbol))
+        {
+            return;
+        }
+
+        context.ReportDiagnostic(Diagnostic.Create(Rule, context.Node.GetLocation(), localDeclaration.Declaration.Variables.First().Identifier.ValueText));
+    }
+}