Tested Application Step 3: Rewrite the Tests You Have

Go through every test you have written so far and apply the three rules: arrange-act-assert visible, named after the behavior, one reason to fail. Split any test asserting several unrelated things. Replace every loose assertion with a specific one. Then run the suite and read only the test names: if you cannot tell what the system does from that list alone, the names need work. That list is the closest thing you will have to documentation that cannot go stale.