Using SpecFlow+ Runner without feature files

[Janis Simsons]

Hello,

Is it possible to use SpecFlow+ Runner to execute NUnit or XUnit or any other framework tests? 

I don't want to write feature files, but I would like to use the SpecFlow+ Runner, because it has excellent parallel execution capabilities.

Or is there any other way to use SpecFlow+ Runner to run tests (doesn't have to be NUnit or XUnit code) without having feature files?

Thank you