Add additional test cases to improve coverage

[quinnj]

No description provided.

[ScottPJones]

This needs to have @static if VERSION >= ... ... end around the tests for parsing arguments at the end of a string.
That causes the tests to fail on older versions of Julia (before Jeff merged in the change I did to make numbers work as string arguments, not just things that looked like symbols)
(and thanks for the extra tests! It's appreciated!)