Add rbenv files to .gitignore.
Remove test-unit dev dependency.
Prefer $LOAD_PATH over $:.
Fixes RSpec configuration.
Refactor spec syntax.
Fixes some code styles.
Add support config files for Rubocop and Hound CI.
Make const of files thats actually used in tests.
Split up grouped tests.
Update regex.
Use a guard clauses instead of wrappings.
Code style of assignments in conditions.
Favor format over String#%.
Avoid using "format" as variable name.

There already exits ruby method named “format” plus method name.
Avoid using rescue in its modifier form.