Feature/first unit tests

Here's the beginning of adding unit tests. There is still a good bit of work to do to improve coverage (currently 33.6% coverage by line).

Also, this PR depends on #2.
I can see this argument. I did this because I ran into a "ArrayIndexOutOfBounds" exception with an empty string for path in the original code. After rereading the docs of Path.resolve(Path), I definitely got this wrong. It says, "If other is an empty path then this method trivially returns this path."  I'll modify to do that.