01basic.t is the only test in this directory which is NOT dynamically
generated by dotty/build_tests. It checks the most basic functioning
of GraphViz::Data::Structure (does it load, does it create an object, etc.)

All of the other tests check to make sure that the output from 
GraphViz::Data::Structure is consistent with what it output when the dotty
tests were run and approved visually.

There may be a better way to handle the tests, but this one seems to provide
the most flexibility in testing the module while allowing all of the tests
to be updated easily when a change is made to the output.