Fixed issue in SA1001 fix all code fix

Author: vweijsters

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/SpacingRules/TokenSpacingCodeFixProvider.cs

@@ -225,7 +225,12 @@ private static void UpdateReplaceMap(Dictionary<SyntaxToken, SyntaxToken> replac
                 case TokenSpacingProperties.ActionInsert:
                     if (!replaceMap.ContainsKey(nextToken))
                     {
-                        replaceMap[token] = token.WithTrailingTrivia(token.TrailingTrivia.Insert(0, SyntaxFactory.Space));
+                        // If the token is already present in the map and it has trailing trivia, then it has already been
+                        // processed during an earlier step in the fix all process, so no additional processing is needed.
+                        if (!replaceMap.ContainsKey(token) || (replaceMap[token].TrailingTrivia.Count == 0))
+                        {
+                            replaceMap[token] = token.WithTrailingTrivia(token.TrailingTrivia.Insert(0, SyntaxFactory.Space));
+                        }
                     }
 
                     break;

StyleCop.Analyzers/StyleCop.Analyzers.Test/SpacingRules/SA1001UnitTests.cs

@@ -227,6 +227,55 @@ void MethodName()
             await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        [WorkItem(2468, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/2468")]
+        public async Task TestCodeFixCommaPlacementAsync()
+        {
+            var testCode = @"using System;
+
+public class TestClass
+{
+    public void TestMethod()
+    {
+        var test = (new[]
+        {
+            new Tuple<int, int>(1, 2)
+           ,new Tuple<int, int>(3, 4)
+           ,new Tuple<int, int>(5, 6)
+        }).ToString();
+    }
+}
+";
+
+            var fixedCode = @"using System;
+
+public class TestClass
+{
+    public void TestMethod()
+    {
+        var test = (new[]
+        {
+            new Tuple<int, int>(1, 2),
+           new Tuple<int, int>(3, 4),
+           new Tuple<int, int>(5, 6)
+        }).ToString();
+    }
+}
+";
+
+            DiagnosticResult[] expected =
+            {
+                this.CSharpDiagnostic().WithArguments(" not", "preceded").WithLocation(10, 12),
+                this.CSharpDiagnostic().WithArguments(string.Empty, "followed").WithLocation(10, 12),
+                this.CSharpDiagnostic().WithArguments(" not", "preceded").WithLocation(11, 12),
+                this.CSharpDiagnostic().WithArguments(string.Empty, "followed").WithLocation(11, 12),
+            };
+
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
+        }
+
         protected override IEnumerable<DiagnosticAnalyzer> GetCSharpDiagnosticAnalyzers()
         {
             yield return new SA1001CommasMustBeSpacedCorrectly();