From e96a5c88a76f5ef168ea600abdca4f98e5304280 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20M=C3=BCller?= <muellerdavid4@gmail.com>
Date: Sat, 26 Feb 2022 03:31:57 +0100
Subject: [PATCH] imp + test + changelog

---
 Documentation/Changelog.md                    |  5 ++++
 .../Instrumentation/Instrumenter.cs           | 20 ++++++++++++++
 ...erageTests.ExcludeFromCoverageAttribute.cs | 27 +++++++++++++++++++
 ...mentation.ExcludeFromCoverage.Issue1302.cs | 18 +++++++++++++
 4 files changed, 70 insertions(+)
 create mode 100644 test/coverlet.core.tests/Samples/Instrumentation.ExcludeFromCoverage.Issue1302.cs

diff --git a/Documentation/Changelog.md b/Documentation/Changelog.md
index 5c551ceec..06daa9310 100644
--- a/Documentation/Changelog.md
+++ b/Documentation/Changelog.md
@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+-ExcludeFromCodeCoverage attribute on local functions ignores lambda expression [#1302](https://github.com/coverlet-coverage/coverlet/issues/1302)
+
 ## Release date 2022-02-06
 ### Packages  
 coverlet.msbuild 3.1.2  
diff --git a/src/coverlet.core/Instrumentation/Instrumenter.cs b/src/coverlet.core/Instrumentation/Instrumenter.cs
index 51b18c07c..42a1a1835 100644
--- a/src/coverlet.core/Instrumentation/Instrumenter.cs
+++ b/src/coverlet.core/Instrumentation/Instrumenter.cs
@@ -45,6 +45,7 @@ internal class Instrumenter
         private List<string> _excludedSourceFiles;
         private List<string> _branchesInCompiledGeneratedClass;
         private List<(MethodDefinition, int)> _excludedMethods;
+        private List<string> _excludedLambdaMethods;
         private List<string> _excludedCompilerGeneratedTypes;
         private readonly string[] _doesNotReturnAttributes;
         private ReachabilityHelper _reachabilityHelper;
@@ -500,12 +501,18 @@ private void InstrumentType(TypeDefinition type)
                     continue;
                 }
 
+                if (_excludedLambdaMethods != null && _excludedLambdaMethods.Contains(method.FullName))
+                {
+                    continue;
+                }
+
                 if (!customAttributes.Any(IsExcludeAttribute))
                 {
                     InstrumentMethod(method);
                 }
                 else
                 {
+                    (_excludedLambdaMethods ??= new List<string>()).AddRange(CollectLambdaMethodsInsideLocalFunction(method));
                     (_excludedMethods ??= new List<(MethodDefinition, int)>()).Add((method, ordinal));
                 }
             }
@@ -842,6 +849,19 @@ internal bool IsSynthesizedNameOf(string name, string methodName, int methodOrdi
                 (name.IndexOf($"<{methodName}>g__") != -1 && name.IndexOf($"|{methodOrdinal}_") != -1);
         }
 
+        private static IEnumerable<string> CollectLambdaMethodsInsideLocalFunction(MethodDefinition methodDefinition)
+        {
+            if (!methodDefinition.Name.Contains(">g__")) yield break;
+
+            foreach (Instruction instruction in methodDefinition.Body.Instructions.ToList())
+            {
+                if (instruction.OpCode == OpCodes.Ldftn && instruction.Operand is MethodReference mr && mr.Name.Contains(">b__"))
+                {
+                    yield return mr.FullName;
+                }
+            }
+        }
+
         /// <summary>
         /// A custom importer created specifically to allow the instrumentation of System.Private.CoreLib by
         /// removing the external references to netstandard that are generated when instrumenting a typical
diff --git a/test/coverlet.core.tests/Coverage/CoverageTests.ExcludeFromCoverageAttribute.cs b/test/coverlet.core.tests/Coverage/CoverageTests.ExcludeFromCoverageAttribute.cs
index e989c3838..bead5b913 100644
--- a/test/coverlet.core.tests/Coverage/CoverageTests.ExcludeFromCoverageAttribute.cs
+++ b/test/coverlet.core.tests/Coverage/CoverageTests.ExcludeFromCoverageAttribute.cs
@@ -277,5 +277,32 @@ public void ExcludeFromCodeCoverageAutoGeneratedGet()
                 File.Delete(path);
             }
         }
+
+        [Fact]
+        public void ExcludeFromCodeCoverage_Issue1302()
+        {
+            string path = Path.GetTempFileName();
+            try
+            {
+                FunctionExecutor.Run(async (string[] pathSerialize) =>
+                {
+                    CoveragePrepareResult coveragePrepareResult = await TestInstrumentationHelper.Run<Issue1302>(instance =>
+                    {
+                        instance.Run();
+                        return Task.CompletedTask;
+                    }, persistPrepareResultToFile: pathSerialize[0]);
+
+                    return 0;
+                }, new string[] { path });
+
+                TestInstrumentationHelper.GetCoverageResult(path)
+                    .Document("Instrumentation.ExcludeFromCoverage.Issue1302.cs")
+                    .AssertNonInstrumentedLines(BuildConfiguration.Debug, 10, 13);
+            }
+            finally
+            {
+                File.Delete(path);
+            }
+        }
     }
 }
diff --git a/test/coverlet.core.tests/Samples/Instrumentation.ExcludeFromCoverage.Issue1302.cs b/test/coverlet.core.tests/Samples/Instrumentation.ExcludeFromCoverage.Issue1302.cs
new file mode 100644
index 000000000..8bf8dd2d4
--- /dev/null
+++ b/test/coverlet.core.tests/Samples/Instrumentation.ExcludeFromCoverage.Issue1302.cs
@@ -0,0 +1,18 @@
+using System;
+
+namespace Coverlet.Core.Samples.Tests
+{
+    public class Issue1302
+    {
+        public void Run()
+        {
+            [System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+            static Func<string, bool> LocalFunction()
+            {
+                return myString => myString.Length == 10;
+            }
+
+            LocalFunction();
+        }
+    }
+}