Test On Espresso If A Dialog Fragment is Shown When a Button is Clicked

How do I make a test on Espresso where I could check whether a Dialog Fragment is shown when a Button is clicked?

I've been searching but never really found an answer.

Also could someone please guide me with TDD in Android. I've read alot but don't actually know how to start. I also dont understand the 70, 20, 10 rule. How do you know you are hitting them?

Also How do I know If I'm doing a Integration test over a Intrucmentation Test? I just really started studying these things and I'm frustrated and lost. Can please someone explain these things to me? :(

I really wanted to start developing with test in mind to improve my development cycle. Any help would be appreciated. Thanks in advance.