SA1001 no longer accepts commas as first token on a line

Author: vweijsters

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

@@ -72,15 +72,23 @@ public async Task TestLastCommaInLineAsync()
         [Fact]
         public async Task TestFirstCommaInLineAsync()
         {
-            string statement = $"f(a{Environment.NewLine}, b);";
-            await this.TestCommaInStatementOrDeclAsync(statement, EmptyDiagnosticResults, statement).ConfigureAwait(false);
+            string testStatement = $"f(a{Environment.NewLine}, b);";
+            string fixedStatement = $"f(a,{Environment.NewLine}b);";
+
+            DiagnosticResult expected = this.CSharpDiagnostic().WithArguments(" not", "preceded").WithLocation(8, 1);
+
+            await this.TestCommaInStatementOrDeclAsync(testStatement, expected, fixedStatement).ConfigureAwait(false);
         }
 
         [Fact]
         public async Task TestCommentBeforeFirstCommaInLineAsync()
         {
-            string statement = $"f(a // comment{Environment.NewLine}, b);";
-            await this.TestCommaInStatementOrDeclAsync(statement, EmptyDiagnosticResults, statement).ConfigureAwait(false);
+            string testStatement = $"f(a // comment{Environment.NewLine}, b);";
+            string fixedStatement = $"f(a, // comment{Environment.NewLine}b);";
+
+            DiagnosticResult expected = this.CSharpDiagnostic().WithArguments(" not", "preceded").WithLocation(8, 1);
+
+            await this.TestCommaInStatementOrDeclAsync(testStatement, expected, fixedStatement).ConfigureAwait(false);
         }
 
         [Fact]

StyleCop.Analyzers/StyleCop.Analyzers/SpacingRules/SA1001CommasMustBeSpacedCorrectly.cs

@@ -27,7 +27,7 @@ internal class SA1001CommasMustBeSpacedCorrectly : DiagnosticAnalyzer
         /// </summary>
         public const string DiagnosticId = "SA1001";
         private const string Title = "Commas must be spaced correctly";
-        private const string MessageFormat = "Commas must{0} be {1} by a space.";
+        private const string MessageFormat = "Commas must{0} be {1} by whitespace.";
         private const string Description = "The spacing around a comma is incorrect, within a C# code file.";
         private const string HelpLink = "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/blob/master/documentation/SA1001.md";
 
@@ -99,21 +99,15 @@ private static void HandleCommaToken(SyntaxTreeAnalysisContext context, SyntaxTo
                 }
             }
 
-            bool hasPrecedingSpace = false;
-            if (!token.IsFirstInLine())
+            if (token.IsFirstInLine() || token.IsPrecededByWhitespace())
             {
-                hasPrecedingSpace = token.IsPrecededByWhitespace();
-            }
-
-            if (hasPrecedingSpace)
-            {
-                // comma must{ not} be {preceded} by a space
-                context.ReportDiagnostic(Diagnostic.Create(Descriptor, token.GetLocation(), TokenSpacingProperties.RemovePreceding, " not", "preceded"));
+                // comma must{ not} be {preceded} by whitespace
+                context.ReportDiagnostic(Diagnostic.Create(Descriptor, token.GetLocation(), TokenSpacingProperties.RemovePrecedingPreserveLayout, " not", "preceded"));
             }
 
             if (missingFollowingSpace)
             {
-                // comma must{} be {followed} by a space
+                // comma must{} be {followed} by whitespace
                 context.ReportDiagnostic(Diagnostic.Create(Descriptor, token.GetLocation(), TokenSpacingProperties.InsertFollowing, string.Empty, "followed"));
             }
         }

documentation/SA1001.md

@@ -23,7 +23,7 @@ The spacing around a comma is incorrect, within a C# code file.
 
 A violation of this rule occurs when the spacing around a comma is incorrect.
 
-A comma should always be followed by a single space, unless it is the last character on the line, and a comma should never be preceded by any whitespace, unless it is the first character on the line.
+A comma should always be followed by a single space, unless it is the last character on the line, and a comma should never be preceded by any whitespace.
 
 ## How to fix violations