#6 using existing field IFileSystem for FileServiceConstructorInitialCodeAction

Author: inyutin-maxim

System.IO.Abstractions.Analyzers.Tests/CodeFixes/FileServiceConstructorInitialCodeFixTests.cs

@@ -12,6 +12,7 @@ public class FileServiceConstructorInitialCodeFixTests :
 	{
 		[Theory]
 		[InlineData("BeforeFix.txt", "AfterFix.txt")]
+		[InlineData("BeforeFixWithCustomField.txt", "AfterFixWithCustomField.txt")]
 		public void CodeFix(string sourceBefore, string sourceAfter)
 		{
 			var sourceBeforeFix = ReadFile(sourceBefore);

System.IO.Abstractions.Analyzers.Tests/TestData/CodeFix/FileServiceConstructorInitialCodeFix/AfterFixWithCustomField.txt

@@ -0,0 +1,25 @@
+using System.IO;
+using System.IO.Abstractions;
+
+namespace SomeNameSpace
+{
+	public class WithOutFileSystem
+	{
+		private readonly IFileSystem _fSystem;
+
+		public WithOutFileSystem()
+		{
+			_fSystem = new FileSystem();
+		}
+
+		public void SomeMethod()
+		{
+			const string filePath = "C:\\temp.txt";
+
+			if (File.Exists(filePath))
+			{
+				File.Delete(filePath);
+			}
+		}
+	}
+}

System.IO.Abstractions.Analyzers.Tests/TestData/CodeFix/FileServiceConstructorInitialCodeFix/BeforeFixWithCustomField.txt

@@ -0,0 +1,23 @@
+using System.IO;
+
+namespace SomeNameSpace
+{
+	public class WithOutFileSystem
+	{
+		private readonly IFileSystem _fSystem;
+
+		public WithOutFileSystem()
+		{
+		}
+
+		public void SomeMethod()
+		{
+			const string filePath = "C:\\temp.txt";
+
+			if (File.Exists(filePath))
+			{
+				File.Delete(filePath);
+			}
+		}
+	}
+}

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

@@ -74,10 +74,10 @@ protected override async Task<Document> GetChangedDocumentAsync(CancellationToke
 			return editor.GetChangedDocument();
 		}
 
-		private static ExpressionStatementSyntax CreateAssignmentExpression()
+		private static ExpressionStatementSyntax CreateAssignmentExpression(string field = Constants.FieldFileSystemName)
 		{
 			return SyntaxFactory.ExpressionStatement(SyntaxFactory.AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
-				SyntaxFactory.IdentifierName(Constants.FieldFileSystemName),
+				SyntaxFactory.IdentifierName(field),
 				SyntaxFactory.ObjectCreationExpression(SyntaxFactory.IdentifierName(Constants.FileSystemClassName))
 					.WithArgumentList(SyntaxFactory.ArgumentList())));
 		}
@@ -94,7 +94,17 @@ private static void ConstructorAddParameter(ClassDeclarationSyntax classDeclarat
 
 			if (!RoslynClassFileSystem.ConstructorHasAssignmentExpression(newConstructor))
 			{
-				newConstructor = newConstructor.AddBodyStatements(CreateAssignmentExpression());
+				if (RoslynClassFileSystem.HasFileSystemField(classDeclaration))
+				{
+					var fileSystem = RoslynClassFileSystem.GetFileSystemFieldFromClass(classDeclaration);
+
+					newConstructor =
+						newConstructor.AddBodyStatements(CreateAssignmentExpression(fileSystem.Declaration.Variables.ToFullString()));
+				} else
+				{
+					newConstructor =
+						newConstructor.AddBodyStatements(CreateAssignmentExpression());
+				}
 			}
 
 			if (RoslynClassFileSystem.HasConstructor(classDeclaration))