title: How can I get code coverage for dart runtime?
body: <p>Briefly: Can anyone tell me how to know if the dart code has been invoked or how to mark it as hits and misses.</p>
  
  <p>We can get test coverage by 'flutter test --coverage'. But this rely on test.dart file, I mean we have to write test.dart file for the file and function we care about. If we can collect the coverage info when dart is running, it will be easier for us to know which code lines has been invoked. And I think it will be friendly for developers.</p>
  
  <p>I have searched dart-lang/sdk, only know that 'flutter test --coverage' gets reports by invokeRpcRaw('getSourceReport'...), but I have no idea how to get reports for dart runtime.</p>
  
  <p>If runtime dose not work, can I do something when compile?</p>