Interface to be implemented by all Surefire providers.
NOTE: This class is part of the proposed public api for surefire providers for 2.7. It may
still be subject to changes, even for minor revisions.
The api covers this interface and all the types reachable from it. And nothing else.
Called in one of three ways:
Forkmode = never: getSuites is not called, invoke is called with null parameter
Forkmode = once: getSuites is not called, invoke is called with null parameter
Forkmode anything else: getSuites is called, invoke is called on new provider instance for each item in getSuites
Makes an attempt at cancelling the current run, giving the provider a chance to notify
reporting that the remaining tests have been cancelled due to timeout.
If the provider thinks it can terminate properly it is the responsibility of
the invoke method to return a RunResult with a booter code of failure.
It is up to the provider to find out how to implement this method properly.
A provider may also choose to not do anything at all in this method,
which means surefire will kill the forked process soon afterwards anyway.
Will be called on a different thread than the one calling invoke.