So what can you do to avoid getting into this situation. On of the best advices I can give to a developer is: 'Whatever you do, do not lie to a software tester!'.
Not only will (good) testers find out sooner or later, they will put the spotlights on you once you lied to them.
Don't under estimate testers in finding out you are telling the truth as a developer, in 10 years of testing you can learn a lot on finding out if a developer knows what he is doing or just... trying to fix things. We sense like a shark senses a drip of blood from miles away.