Tidyup

Proposed updates to modernise code. A few more updates to come.
Technically it is fine, so this is just your preference? I don't like modifying global state, e.g. `$LOAD_PATH` - that feels like a hack to me just to get the test files to load correctly.

I'd rather get rid of the helper alltogether but unfortunately there are too many regressions in minitest which is the current best option going forward.