After I upgraded Magento manually (copied the files of 1.7 into my Magento 1.6) I had some errors coming from Code in
Fatal error: Undefined class constant 'TYPE_BILLING' in [...]/app/code/core/Mage/Sales/Model/Quote.php on line 547
In this case the problem was in:
I copied the new version of Abstract.php and put the changes into the new file.
There where some other similar errors that I fixed the same way.
Now I dont get any bugs anymore by clicked around, but how can I be sure I found everything? There is quite a lot in the
app\code\local\Mage folder and to check all files manually will take forever.
So how do you check the custom adaptations in