Improved opencover coverage detection

appveyor.yml

@@ -15,5 +15,5 @@ build_script:
 
 test_script:
  - dotnet build /t:Rebuild /p:DebugType=full /p:DebugSymbols=true EternalArrowBackup.sln
- - ps: Get-ChildItem *.Tests.csproj -Recurse | % {C:\ProgramData\chocolatey\lib\opencover.portable\tools\OpenCover.Console -register -target:"C:\Program Files\dotnet\dotnet.exe" -targetargs:"test --no-build --logger:trx;LogFileName=results.trx --filter Category!=Integration $_" -filter:"+[*]* -[*.Tests]*" -mergeoutput -output:OpenCover.xml -oldStyle}
+ - ps: Get-ChildItem *.Tests.csproj -Recurse | % {C:\ProgramData\chocolatey\lib\opencover.portable\tools\OpenCover.Console -register -target:"C:\Program Files\dotnet\dotnet.exe" -targetargs:"test --no-build --logger:trx;LogFileName=results.trx --filter Category!=Integration $_" -filter:"+[*]* -[*.Tests]*" -showunvisited -mergeoutput -output:OpenCover.xml -oldStyle}
  - codecov -f OpenCover.xml