Add OpenCover coverage for C#
diff --git a/src/csharp/.gitignore b/src/csharp/.gitignore
index deac550..0f96a48 100644
--- a/src/csharp/.gitignore
+++ b/src/csharp/.gitignore
@@ -7,6 +7,7 @@
 Grpc.sdf
 
 TestResult.xml
+coverage_results.xml
 /TestResults
 .vs/
 *.nupkg