Python tracing and conditional jumps

There is no information in the trace facility about the last branch taken.

What I did to implement branch coverage measurement in coverage.py is to keep a record for each stack frame of the last line executed, then the next time the trace function is called, I can record a pair of line numbers which form a from-to arc of execution.

About finer-grained tracing: you can trick the Python interpreter into giving you byte code information. My experiment in this is described here: Wicked hack: Python bytecode tracing

I'd be very interested to see how this work progresses!