editor command processing

Is there a preferred way to determine if an editor command has 
completed executing? I'm finding it to be quite a challenge to write 
code to test the editor. Functions have to be called in the interface 
process which in turn calls editor:process-character to run something 
in the editor process. So the test code might close the interface which 
generates an error because the operation on the editor pane has not yet 
completed.

Thanks for any suggestions,

John DeSoi, Ph.D.