> Of course this strategy requires you to have good tests.
Not necessarily, if you also follow another similar principle. Leave the code a little neater than you found it, but also leave the code a little more well tested than you found it!
Could you distinguish between "good tests" and "a little more well tested"?
It seems to me that good tests enable code to be well tested. Here, "good tests" would be verification of behaviour by using the various expected and unexpected input and output.
Not necessarily, if you also follow another similar principle. Leave the code a little neater than you found it, but also leave the code a little more well tested than you found it!