CSS selector testing

Are there any good tools or methods for testing css selectors?

I'm developing a SCSS framework and would like to include tests in it. Specifically I would like to have tests to ensure that the css selectors are working properly.

Say for instance that I have the html:

<input class="btn" disabled id="test"></input>

and css

.btn {
 color: red;
 ...
}

.btn:disabled {
 color: green;
 ...
}

I would like to have a test that ensures that the element with id=test, have the .btn:disabled as the "primary" css class and .btn as the "secondary".

I'm thinking of doing this in selenium. Are there any good ways of doing this? I would not like to hard code the css values into the tests.