“The only purpose of the app is basically to pull a list of contacts”
Okay. Test that. What does “pull” mean? That sounds like “logic”.
” display them on a page”
Okay. Test that. Right ones displayed? Everything there?
” display a form to send a message,”
Okay. Test that. Right fields? Validations of inputs all work?
” and the like.”
Okay. Test that. Do the queries work? Find the right data? Display the right data? Validate the inputs? Produce the right error messages for the invalid inputs?