What common mistake do developers make with Database isolation, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Database isolation, why does the mistake cause problems, and what is the safer approach? One recurring problem with database isolation is applying it without understanding the boundary it protects. Writing a test that only asserts a 200 response while never verifying that the important application state actually changed. In addition, Tests should avoid relying on leftover records from previous test runs. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.