Fix enum values

[dwightwatson]

I think when I converted this from the previous enum implementation to the native implemenation I made a mistake by setting unspecified to private as well.

• This fixes the enum by setting the value of the string to match the case,
• It also adds test coverage for this and the other enum values.

Closes #141

[DiedeGu]

Hi I reviewed the code, it looks good, but Scrutinizer is failing.