Respect PreferParameterNullChecking user option

src/EditorFeatures/CSharpTest/InitializeParameter/AddParameterCheckTests.cs

@@ -29,8 +29,10 @@ public async Task TestEmptyFile()
             await VerifyCS.VerifyRefactoringAsync(code, code);
         }
 
-        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsInitializeParameter)]
-        public async Task TestSimpleReferenceType()
+        [Theory, Trait(Traits.Feature, Traits.Features.CodeActionsInitializeParameter)]
+        [InlineData("csharp_style_prefer_parameter_null_checking = true")]
+        [InlineData("")]
+        public async Task TestSimpleReferenceType(string editorConfig)
         {
             await new VerifyCS.Test
             {
@@ -52,7 +54,46 @@ class C
     public C(string s!!)
     {
     }
-}"
+}",
+                EditorConfig = $@"
+[*]
+{editorConfig}
+"
+            }.RunAsync();
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsInitializeParameter)]
+        public async Task TestDoNotPreferParameterNullChecking()
+        {
+            await new VerifyCS.Test
+            {
+                LanguageVersion = LanguageVersionExtensions.CSharpNext,
+                TestCode = @"
+using System;
+
+class C
+{
+    public C([||]string s)
+    {
+    }
+}",
+                FixedCode = @"
+using System;
+
+class C
+{
+    public C(string s)
+    {
+        if (s is null)
+        {
+            throw new ArgumentNullException(nameof(s));
+        }
+    }
+}",
+                EditorConfig = @"
+[*]
+csharp_style_prefer_parameter_null_checking = false
+",
             }.RunAsync();
         }
 

src/Features/CSharp/Portable/InitializeParameter/CSharpAddParameterCheckCodeRefactoringProvider.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Composition;
 using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeRefactorings;
 using Microsoft.CodeAnalysis.CSharp.CodeStyle;
 using Microsoft.CodeAnalysis.CSharp.Extensions;
@@ -102,14 +103,18 @@ protected override StatementSyntax CreateParameterCheckIfStatement(DocumentOptio
                 @else: null);
         }
 
-        protected override Document? TryAddNullCheckToParameterDeclaration(Document document, ParameterSyntax parameterSyntax, CancellationToken cancellationToken)
+        protected override async Task<Document?> TryAddNullCheckToParameterDeclarationAsync(Document document, ParameterSyntax parameterSyntax, CancellationToken cancellationToken)
         {
             var tree = parameterSyntax.SyntaxTree;
             if (!tree.Options.LanguageVersion().IsCSharp11OrAbove())
                 return null;
 
+            var options = await document.GetOptionsAsync(cancellationToken).ConfigureAwait(false);
+            if (!options.GetOption(CSharpCodeStyleOptions.PreferParameterNullChecking).Value)
+                return null;
+
             // We expect the syntax tree to already be in memory since we already have a node from the tree
-            var syntaxRoot = tree.GetRoot(cancellationToken);
+            var syntaxRoot = await tree.GetRootAsync(cancellationToken).ConfigureAwait(false);
             syntaxRoot = syntaxRoot.ReplaceNode(
                 parameterSyntax,
                 parameterSyntax.WithExclamationExclamationToken(Token(SyntaxKind.ExclamationExclamationToken)));

src/Features/Core/Portable/InitializeParameter/AbstractAddParameterCheckCodeRefactoringProvider.cs

@@ -42,7 +42,7 @@ internal abstract partial class AbstractAddParameterCheckCodeRefactoringProvider
         protected abstract bool PrefersThrowExpression(DocumentOptionSet options);
         protected abstract string EscapeResourceString(string input);
         protected abstract TStatementSyntax CreateParameterCheckIfStatement(DocumentOptionSet options, TExpressionSyntax condition, TStatementSyntax ifTrueStatement);
-        protected abstract Document? TryAddNullCheckToParameterDeclaration(Document document, TParameterSyntax parameterSyntax, CancellationToken cancellationToken);
+        protected abstract Task<Document?> TryAddNullCheckToParameterDeclarationAsync(Document document, TParameterSyntax parameterSyntax, CancellationToken cancellationToken);
 
         protected override async Task<ImmutableArray<CodeAction>> GetRefactoringsForAllParametersAsync(
             Document document,
@@ -331,7 +331,7 @@ private async Task<Document> AddNullCheckAsync(
             CancellationToken cancellationToken)
         {
             // First see if we can adopt the '!!' parameter null checking syntax.
-            var modifiedDocument = TryAddNullCheckToParameterDeclaration(document, parameterSyntax, cancellationToken);
+            var modifiedDocument = await TryAddNullCheckToParameterDeclarationAsync(document, parameterSyntax, cancellationToken).ConfigureAwait(false);
             if (modifiedDocument != null)
             {
                 return modifiedDocument;

src/Features/VisualBasic/Portable/InitializeParameter/VisualBasicAddParameterCheckCodeRefactoringProvider.vb

@@ -72,8 +72,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.InitializeParameter
                 elseBlock:=Nothing)
         End Function
 
-        Protected Overrides Function TryAddNullCheckToParameterDeclaration(document As Document, parameterSyntax As ParameterSyntax, cancellationToken As CancellationToken) As Document
-            Return Nothing
+        Protected Overrides Function TryAddNullCheckToParameterDeclarationAsync(document As Document, parameterSyntax As ParameterSyntax, cancellationToken As CancellationToken) As Task(Of Document)
+            Return Task.FromResult(Of Document)(Nothing)
         End Function
     End Class
 End Namespace