Complete FileServiceInterfaceInjectionCodeAction

Author: inyutin-maxim

Roslyn.Testing/CodeFix/CSharpCodeFixProviderTest.cs

@@ -76,7 +76,7 @@ protected void VerifyFix(string oldSource,
 
 			if (string.IsNullOrEmpty(result.ErrorMessage))
 			{
-				result.NewSource.ShouldBe(result.ActualSource);
+				result.NewSource.ShouldContainWithoutWhitespace(result.ActualSource);
 			} else
 			{
 				result.Success.ShouldBeTrue(result.ErrorMessage);

System.IO.Abstractions.Analyzers/CodeActions/FileServiceInterfaceInjectionCodeAction.cs

@@ -34,10 +34,7 @@ protected override async Task<Document> GetChangedDocumentAsync(CancellationToke
 		{
 			var editor = await DocumentEditor.CreateAsync(_document, cancellationToken).ConfigureAwait(false);
 
-			var parameter = SF.Parameter(SF.Identifier("fileSystem"))
-				.WithType(SF.ParseTypeName(Constants.FileSystemName))
-				.WithAdditionalAnnotations(Formatter.Annotation, Simplifier.Annotation)
-				.NormalizeWhitespace();
+			var parameter = CreateFileSystemParameterDeclaration();
 
 			if (!(_constructor.Parent is ClassDeclarationSyntax classDeclarationSyntax))
 			{
@@ -55,19 +52,71 @@ protected override async Task<Document> GetChangedDocumentAsync(CancellationToke
 				return editor.GetChangedDocument();
 			}
 
-			var fileSystemPropertyDeclaration = SF.FieldDeclaration(SF.VariableDeclaration(SF.IdentifierName(Constants.FileSystemName))
-					.WithVariables(SF.SingletonSeparatedList(SF.VariableDeclarator(SF.Identifier("_fileSystem")))))
-				.WithModifiers(SF.TokenList(SF.Token(SyntaxKind.PrivateKeyword),
-					SF.Token(SyntaxKind.ReadOnlyKeyword)));
+			var fileSystemPropertyDeclaration = CreateFileSystemPropertyDeclaration();
 
 			editor.InsertMembers(classDeclarationSyntax,
 				0,
 				new SyntaxNode[]
-					{ fileSystemPropertyDeclaration });
+				{
+					fileSystemPropertyDeclaration
+				});
+
+			var newConstructor = _constructor.WithBody(_constructor.Body.AddStatements(CreateAssignmentExpression()))
+				.AddParameterListParameters(parameter)
+				.WithAdditionalAnnotations(Formatter.Annotation, Simplifier.Annotation)
+				.NormalizeWhitespace();
+
+			editor.ReplaceNode(_constructor, newConstructor);
+			var compilationUnitSyntax = GetCompilationUnit(_constructor);
 
-			editor.AddParameter(_constructor, parameter);
+			editor.ReplaceNode(compilationUnitSyntax.Usings.FirstOrDefault(),
+				SF.UsingDirective(SF.ParseName(Constants.FileSystemNameSpace)));
 
 			return editor.GetChangedDocument();
 		}
+
+		private static FieldDeclarationSyntax CreateFileSystemPropertyDeclaration()
+		{
+			return SF.FieldDeclaration(SF.VariableDeclaration(CreateFileSystemType())
+					.WithVariables(SF.SingletonSeparatedList(SF.VariableDeclarator(SF.Identifier("_fileSystem")))))
+				.WithModifiers(SF.TokenList(SF.Token(SyntaxKind.PrivateKeyword),
+					SF.Token(SyntaxKind.ReadOnlyKeyword)));
+		}
+
+		private static ParameterSyntax CreateFileSystemParameterDeclaration()
+		{
+			return SF.Parameter(SF.Identifier("fileSystem"))
+				.WithType(CreateFileSystemType())
+				.WithAdditionalAnnotations(Formatter.Annotation, Simplifier.SpecialTypeAnnotation)
+				.NormalizeWhitespace();
+		}
+
+		private static TypeSyntax CreateFileSystemType()
+		{
+			return SF.ParseTypeName(Constants.FileSystemName);
+		}
+
+		private static ExpressionStatementSyntax CreateAssignmentExpression()
+		{
+			return SF.ExpressionStatement(SF.AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+				SF.IdentifierName("_fileSystem"),
+				SF.IdentifierName("fileSystem")));
+		}
+
+		private CompilationUnitSyntax GetCompilationUnit(SyntaxNode node)
+		{
+			switch (node)
+			{
+				case null:
+
+					return null;
+				case CompilationUnitSyntax compilationUnitSyntax:
+
+					return compilationUnitSyntax;
+				default:
+
+					return GetCompilationUnit(node.Parent);
+			}
+		}
 	}
 }