Fix coverage issue for finally block with await (#1245)

Fix coverage issue for finally block with await

Documentation/Changelog.md

@@ -7,9 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 ### Fixed 
+-Fix branch coverage issue for finally block with await [#1233](https://github.com/coverlet-coverage/coverlet/issues/1233)
 -Fix threshold doesn't work when coverage empty [#1205](https://github.com/coverlet-coverage/coverlet/issues/1205)  
 -Fix branch coverage issue for il switch [#1177](https://github.com/coverlet-coverage/coverlet/issues/1177)  
--Fix branch coverage with using statement and several awaits[#1176](https://github.com/coverlet-coverage/coverlet/issues/1176)  
+-Fix branch coverage with using statement and several awaits[#1176](https://github.com/coverlet-coverage/coverlet/issues/1176)
 
 ### Improvements  
 -Improve logging in case of exception inside static ctor of NetstandardAwareAssemblyResolver [#1230](https://github.com/coverlet-coverage/coverlet/pull/1230)  

src/coverlet.core/Symbols/CecilSymbolHelper.cs

@@ -543,9 +543,9 @@ namespace Coverlet.Core.Symbols
                         instructions[i].Operand is FieldDefinition field &&
                         IsCompilerGenerated(field) && field.FieldType.FullName == "System.Object")
                     {
-                        // We expect the call to GetResult() to be no more than three
+                        // We expect the call to GetResult() to be no more than four
                         // instructions before the loading of the field's value.
-                        int minCallIndex = Math.Max(0, i - 3);
+                        int minCallIndex = Math.Max(0, i - 4);
 
                         for (int j = i - 1; j >= minCallIndex; --j)
                         {

test/coverlet.core.tests/Coverage/CoverageTests.AsyncAwait.cs

@@ -154,5 +154,33 @@ namespace Coverlet.Core.Tests
                 File.Delete(path);
             }
         }
+
+        [Fact]
+        public void AsyncAwait_Issue_1233()
+        {
+            string path = Path.GetTempFileName();
+            try
+            {
+                FunctionExecutor.Run(async (string[] pathSerialize) =>
+                {
+                    CoveragePrepareResult coveragePrepareResult = await TestInstrumentationHelper.Run<Issue_1233>(instance =>
+                        {
+                            ((Task)instance.Test()).ConfigureAwait(false).GetAwaiter().GetResult();
+                            return Task.CompletedTask;
+                        },
+                        persistPrepareResultToFile: pathSerialize[0]);
+
+                    return 0;
+                }, new string[] { path });
+
+                var document = TestInstrumentationHelper.GetCoverageResult(path).Document("Instrumentation.AsyncAwait.cs");
+                document.AssertLinesCovered(BuildConfiguration.Debug, (150, 1));
+                Assert.DoesNotContain(document.Branches, x => x.Key.Line == 150);
+            }
+            finally
+            {
+                File.Delete(path);
+            }
+        }
     }
 }

test/coverlet.core.tests/Samples/Instrumentation.AsyncAwait.cs

@@ -137,4 +137,18 @@ namespace Coverlet.Core.Samples.Tests
             await Task.CompletedTask;
         }
     }
+
+    public class Issue_1233
+    {
+        async public Task Test()
+        {
+            try
+            {
+            }
+            finally
+            {
+                await Task.CompletedTask;
+            }
+        }
+    }
 }