Added an empty string analyzer & code fix

app/SourceCodeRules/SourceCodeRules/AnalyzerReleases.Shipped.md

@@ -10,3 +10,4 @@
  MWAIS0004 | Usage    | Error    | RandomInstantiationAnalyzer    
  MWAIS0005 | Usage    | Error    | ThisUsageAnalyzer              
  MWAIS0006 | Style    | Error    | SwitchExpressionMethodAnalyzer 
+ MWAIS0007 | Usage    | Error    | EmptyStringAnalyzer            

app/SourceCodeRules/SourceCodeRules/Identifier.cs

@@ -8,4 +8,5 @@ public static class Identifier
     public const string RANDOM_INSTANTIATION_ANALYZER = $"{Tools.ID_PREFIX}0004";
     public const string THIS_USAGE_ANALYZER = $"{Tools.ID_PREFIX}0005";
     public const string SWITCH_EXPRESSION_METHOD_ANALYZER = $"{Tools.ID_PREFIX}0006";
+    public const string EMPTY_STRING_ANALYZER = $"{Tools.ID_PREFIX}0007";
 }

app/SourceCodeRules/SourceCodeRules/UsageAnalyzers/EmptyStringAnalyzer.cs

@@ -0,0 +1,68 @@
+using System.Collections.Immutable;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace SourceCodeRules.UsageAnalyzers;
+
+#pragma warning disable RS1038
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+#pragma warning restore RS1038
+public sealed class EmptyStringAnalyzer : DiagnosticAnalyzer
+{
+    private const string DIAGNOSTIC_ID = Identifier.EMPTY_STRING_ANALYZER;
+    
+    private static readonly string TITLE = """
+                                           Use string.Empty instead of ""
+                                           """;
+    
+    private static readonly string MESSAGE_FORMAT = """
+                                                    Use string.Empty instead of ""
+                                                    """;
+    
+    private static readonly string DESCRIPTION = """Empty string literals ("") should be replaced with string.Empty for better code consistency and readability except in const contexts.""";
+    
+    private const string CATEGORY = "Usage";
+    
+    private static readonly DiagnosticDescriptor RULE = new(DIAGNOSTIC_ID, TITLE, MESSAGE_FORMAT, CATEGORY, DiagnosticSeverity.Error, isEnabledByDefault: true, description: DESCRIPTION);
+    
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => [RULE];
+    
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+        context.RegisterSyntaxNodeAction(AnalyzeEmptyStringLiteral, SyntaxKind.StringLiteralExpression);
+    }
+    
+    private static void AnalyzeEmptyStringLiteral(SyntaxNodeAnalysisContext context)
+    {
+        var stringLiteral = (LiteralExpressionSyntax)context.Node;
+        if (stringLiteral.Token.ValueText != string.Empty)
+            return;
+        
+        if (IsInConstContext(stringLiteral))
+            return;
+        
+        var diagnostic = Diagnostic.Create(RULE, stringLiteral.GetLocation());
+        context.ReportDiagnostic(diagnostic);
+    }
+    
+    private static bool IsInConstContext(LiteralExpressionSyntax stringLiteral)
+    {
+        var variableDeclarator = stringLiteral.FirstAncestorOrSelf<VariableDeclaratorSyntax>();
+        if (variableDeclarator is null)
+            return false;
+            
+        var declaration = variableDeclarator.Parent?.Parent;
+        return declaration switch
+        {
+            FieldDeclarationSyntax fieldDeclaration => fieldDeclaration.Modifiers.Any(SyntaxKind.ConstKeyword),
+            LocalDeclarationStatementSyntax localDeclaration => localDeclaration.Modifiers.Any(SyntaxKind.ConstKeyword),
+            
+            _ => false
+        };
+    }
+}

app/SourceCodeRules/SourceCodeRules/UsageCodeFixes/EmptyStringCodeFixProvider.cs

@@ -0,0 +1,54 @@
+using System.Collections.Immutable;
+using System.Composition;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Formatting;
+
+namespace SourceCodeRules.UsageCodeFixes;
+
+[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(EmptyStringCodeFixProvider)), Shared]
+public class EmptyStringCodeFixProvider : CodeFixProvider
+{
+    private const string TITLE = """Replace "" with string.Empty""";
+    
+    public sealed override ImmutableArray<string> FixableDiagnosticIds => [Identifier.EMPTY_STRING_ANALYZER];
+    
+    public sealed override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;
+    
+    public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken);
+        if(root is null)
+            return;
+        
+        var diagnostic = context.Diagnostics.First();
+        var diagnosticSpan = diagnostic.Location.SourceSpan;
+        
+        if (root.FindToken(diagnosticSpan.Start).Parent is not LiteralExpressionSyntax emptyStringLiteral)
+            return;
+        
+        context.RegisterCodeFix(
+            CodeAction.Create(
+                title: TITLE,
+                createChangedDocument: c => ReplaceWithStringEmpty(context.Document, emptyStringLiteral, c),
+                equivalenceKey: TITLE),
+            diagnostic);
+    }
+    private static async Task<Document> ReplaceWithStringEmpty(Document document, LiteralExpressionSyntax emptyStringLiteral, CancellationToken cancellationToken)
+    {
+        var stringEmptyExpression = SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, SyntaxFactory.IdentifierName("string"), SyntaxFactory.IdentifierName("Empty")).WithAdditionalAnnotations(Formatter.Annotation);
+        var root = await document.GetSyntaxRootAsync(cancellationToken);
+        if (root is null)
+            return document;
+        
+        var newRoot = root.ReplaceNode(emptyStringLiteral, stringEmptyExpression);
+        return document.WithSyntaxRoot(newRoot);
+    }
+}