How to make spec and dummy in ruby gem project

I’m trying to make my first ruby gem project. This is bootstrap form
helper. I do not understand how to properly create spec tests for views
(test forms, inputs) and dummy.

In which folder they should be located and how to write tests? Anybody
can
show a very simple example tests for the forms of views and an example
dummy (layout/test app where I can see how it all will look like)?