fix false positive

Author: MarcoRossignoli

src/coverlet.core/Coverage.cs

@@ -1,12 +1,11 @@
+using Coverlet.Core.Helpers;
+using Coverlet.Core.Instrumentation;
+using Coverlet.Core.Symbols;
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.IO.Compression;
 using System.Linq;
-
-using Coverlet.Core.Helpers;
-using Coverlet.Core.Instrumentation;
-
+
 namespace Coverlet.Core
 {
     public class Coverage
@@ -183,6 +182,18 @@ private void CalculateCoverage()
                         {
                             int ordinal = int.Parse(info[3]);
                             var branch = document.Branches[(start, ordinal)];
+                            // for MoveNext() compiler autogenerated method we need to patch false positive (IAsyncStateMachine for instance) 
+                            // the idea is force same hits on other branch
+                            if (CecilSymbolHelper.IsMoveNext(branch.Method))
+                            {
+                                foreach (var moveNextBranch in document.Branches)
+                                {
+                                    if (moveNextBranch.Value.Method == branch.Method && moveNextBranch.Value != branch)
+                                    {
+                                        moveNextBranch.Value.Hits += hits;
+                                    }
+                                }
+                            }
                             branch.Hits += hits;
                         }
                         else

src/coverlet.core/Symbols/CecilSymbolHelper.cs

@@ -20,6 +20,11 @@ public static class CecilSymbolHelper
         private const int StepOverLineCode = 0xFEEFEE;
         private static readonly Regex IsMovenext = new Regex(@"\<[^\s>]+\>\w__\w(\w)?::MoveNext\(\)$", RegexOptions.Compiled | RegexOptions.ExplicitCapture);
 
+        public static bool IsMoveNext(string fullName)
+        {
+            return IsMovenext.IsMatch(fullName);
+        }
+
         public static List<BranchPoint> GetBranchPoints(MethodDefinition methodDefinition)
         {
             var list = new List<BranchPoint>();