Extract out common FixAll code. It will be used for other diagnostic analyzers we have.

src/Features/CSharp/Portable/InvokeDelegateWithConditionalAccess/InvokeDelegateWithConditionalAccessCodeFixProvider.FixAllProvider.cs

@@ -9,6 +9,7 @@
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeActions;
 using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CodeFixes.FixAllOccurrences;
 using Microsoft.CodeAnalysis.CSharp.Extensions;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -31,7 +32,7 @@ internal partial class InvokeDelegateWithConditionalAccessCodeFixProvider : Code
         /// By taking control ourselves, we can simply make all the tree edits and not have to
         /// try to back-infer textual changes which then may or may not merge properly.
         /// </summary>
-        private class InvokeDelegateWithConditionalAccessFixAllProvider : BatchFixAllProvider
+        private class InvokeDelegateWithConditionalAccessFixAllProvider : DocumentBasedFixAllProvider
         {
             private readonly InvokeDelegateWithConditionalAccessCodeFixProvider _provider;
 
@@ -40,32 +41,8 @@ public InvokeDelegateWithConditionalAccessFixAllProvider(InvokeDelegateWithCondi
                 _provider = provider;
             }
 
-            internal override async Task<CodeAction> GetFixAsync(
-                ImmutableDictionary<Document, ImmutableArray<Diagnostic>> documentsAndDiagnosticsToFixMap,
-                FixAllState fixAllState,
-                CancellationToken cancellationToken)
-            {
-                // Process all documents in parallel.
-                var updatedDocumentTasks = documentsAndDiagnosticsToFixMap.Select(
-                    kvp => FixAsync(fixAllState, kvp.Key, kvp.Value, cancellationToken));
-
-                await Task.WhenAll(updatedDocumentTasks).ConfigureAwait(false);
-
-                var currentSolution = fixAllState.Solution;
-                foreach (var task in updatedDocumentTasks)
-                {
-                    var updatedDocument = await task.ConfigureAwait(false);
-                    currentSolution = currentSolution.WithDocumentSyntaxRoot(
-                        updatedDocument.Id,
-                        await updatedDocument.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false));
-                }
-
-                var title = GetFixAllTitle(fixAllState);
-                return new CodeAction.SolutionChangeAction(title, _ => Task.FromResult(currentSolution));
-            }
-
-            private Task<Document> FixAsync(
-                FixAllState fixAllState, Document document, ImmutableArray<Diagnostic> diagnostics, CancellationToken cancellationToken)
+            protected override Task<Document> FixDocumentAsync(
+                Document document, ImmutableArray<Diagnostic> diagnostics, CancellationToken cancellationToken)
             {
                 // Filter out the diagnostics we created for the faded out code.  We don't want
                 // to try to fix those as well as the normal diagnostics we created.
@@ -78,4 +55,4 @@ public InvokeDelegateWithConditionalAccessFixAllProvider(InvokeDelegateWithCondi
             }
         }
     }
-}
+}
\ No newline at end of file

src/Workspaces/Core/Portable/CodeFixes/FixAllOccurrences/BatchFixAllProvider.cs

@@ -209,36 +209,7 @@ public override async Task<CodeAction> GetFixAsync(FixAllContext fixAllContext)
 
         public virtual string GetFixAllTitle(FixAllState fixAllState)
         {
-            var diagnosticIds = fixAllState.DiagnosticIds;
-            string diagnosticId;
-            if (diagnosticIds.Count() == 1)
-            {
-                diagnosticId = diagnosticIds.Single();
-            }
-            else
-            {
-                diagnosticId = string.Join(",", diagnosticIds.ToArray());
-            }
-
-            switch (fixAllState.Scope)
-            {
-                case FixAllScope.Custom:
-                    return string.Format(WorkspacesResources.Fix_all_0, diagnosticId);
-
-                case FixAllScope.Document:
-                    var document = fixAllState.Document;
-                    return string.Format(WorkspacesResources.Fix_all_0_in_1, diagnosticId, document.Name);
-
-                case FixAllScope.Project:
-                    var project = fixAllState.Project;
-                    return string.Format(WorkspacesResources.Fix_all_0_in_1, diagnosticId, project.Name);
-
-                case FixAllScope.Solution:
-                    return string.Format(WorkspacesResources.Fix_all_0_in_Solution, diagnosticId);
-
-                default:
-                    throw ExceptionUtilities.Unreachable;
-            }
+            return FixAllProvider.GetFixAllTitle(fixAllState);
         }
 
         public virtual async Task<Solution> TryMergeFixesAsync(

src/Workspaces/Core/Portable/CodeFixes/FixAllOccurrences/DocumentBasedFixAllProvider.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.CodeActions;
+
+namespace Microsoft.CodeAnalysis.CodeFixes.FixAllOccurrences
+{
+    /// <summary>
+    /// A simple implementation of <see cref="FixAllProvider"/> that takes care of collecting
+    /// all the diagnostics and fixes all documents in parallel.  The only functionality a 
+    /// subclass needs to provide is how each document will apply all the fixes to all the 
+    /// diagnostics in that document.
+    /// </summary>
+    internal abstract class DocumentBasedFixAllProvider : FixAllProvider
+    {
+        public sealed override async Task<CodeAction> GetFixAsync(FixAllContext fixAllContext)
+        {
+            var documentsAndDiagnosticsToFixMap = await fixAllContext.GetDocumentDiagnosticsToFixAsync().ConfigureAwait(false);
+            return await GetFixAsync(documentsAndDiagnosticsToFixMap, fixAllContext.State, fixAllContext.CancellationToken).ConfigureAwait(false);
+        }
+
+        internal sealed override async Task<CodeAction> GetFixAsync(
+            ImmutableDictionary<Document, ImmutableArray<Diagnostic>> documentsAndDiagnosticsToFixMap, 
+            FixAllState fixAllState, 
+            CancellationToken cancellationToken)
+        {
+            // Process all documents in parallel.
+            var updatedDocumentTasks = documentsAndDiagnosticsToFixMap.Select(
+                kvp => FixDocumentAsync(kvp.Key, kvp.Value, cancellationToken));
+
+            await Task.WhenAll(updatedDocumentTasks).ConfigureAwait(false);
+
+            var currentSolution = fixAllState.Solution;
+            foreach (var task in updatedDocumentTasks)
+            {
+                var updatedDocument = await task.ConfigureAwait(false);
+                currentSolution = currentSolution.WithDocumentSyntaxRoot(
+                    updatedDocument.Id,
+                    await updatedDocument.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false));
+            }
+
+            var title = GetFixAllTitle(fixAllState);
+            return new CodeAction.SolutionChangeAction(title, _ => Task.FromResult(currentSolution));
+        }
+
+        protected abstract Task<Document> FixDocumentAsync(
+            Document document, ImmutableArray<Diagnostic> diagnostics, CancellationToken cancellationToken);
+    }
+}

src/Workspaces/Core/Portable/CodeFixes/FixAllOccurrences/FixAllProvider.cs

@@ -2,9 +2,11 @@
 
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeActions;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CodeFixes
 {
@@ -54,5 +56,39 @@ public virtual IEnumerable<string> GetSupportedFixAllDiagnosticIds(CodeFixProvid
         {
             return Task.FromResult<CodeAction>(null);
         }
+
+        internal static string GetFixAllTitle(FixAllState fixAllState)
+        {
+            var diagnosticIds = fixAllState.DiagnosticIds;
+            string diagnosticId;
+            if (diagnosticIds.Count() == 1)
+            {
+                diagnosticId = diagnosticIds.Single();
+            }
+            else
+            {
+                diagnosticId = string.Join(",", diagnosticIds.ToArray());
+            }
+
+            switch (fixAllState.Scope)
+            {
+                case FixAllScope.Custom:
+                    return string.Format(WorkspacesResources.Fix_all_0, diagnosticId);
+
+                case FixAllScope.Document:
+                    var document = fixAllState.Document;
+                    return string.Format(WorkspacesResources.Fix_all_0_in_1, diagnosticId, document.Name);
+
+                case FixAllScope.Project:
+                    var project = fixAllState.Project;
+                    return string.Format(WorkspacesResources.Fix_all_0_in_1, diagnosticId, project.Name);
+
+                case FixAllScope.Solution:
+                    return string.Format(WorkspacesResources.Fix_all_0_in_Solution, diagnosticId);
+
+                default:
+                    throw ExceptionUtilities.Unreachable;
+            }
+        }
     }
 }
\ No newline at end of file

src/Workspaces/Core/Portable/Workspaces.csproj

@@ -329,6 +329,7 @@
     <Compile Include="CodeCleanup\Providers\SimplificationCodeCleanupProvider.cs" />
     <Compile Include="CodeFixes\CodeFixContext.cs" />
     <Compile Include="CodeFixes\FixAllOccurrences\BatchSimplificationFixAllProvider.cs" />
+    <Compile Include="CodeFixes\FixAllOccurrences\DocumentBasedFixAllProvider.cs" />
     <Compile Include="CodeFixes\FixAllOccurrences\FixAllState.FixAllDiagnosticProvider.cs" />
     <Compile Include="CodeFixes\FixAllOccurrences\FixAllProviderInfo.cs" />
     <Compile Include="CodeFixes\FixAllOccurrences\FixAllState.FixMultipleDiagnosticProvider.cs" />