A named pipe (FIFO) is meant to be opened twice, once for reading only and once for writing only. Generally, the two ends of a named pipe are expected to be opened by different processes although it should still work if one process opens both.

At the least, you should fork at the beginning of testSequence and have the parent return immediately to the event loop. (You will have to handle synchronization for completing the test and reporting a result back to the parent separately; pipe is likely to be useful for this and I have used it in a number of Tk programs to handle slow background tasks in child processes without blocking the GUI thread.) This will effectively require another event-driven task in the parent to verify the state machine behavior as the child makes incremental progress reports, since the test driver and FSM will be in separate processes.

If you insist on your current approach, inserting recursive calls to the event loop to process the events you create in testSequence is exactly what you must do.