> An all-powerful god who creates subjects that are capable of failing a test of his own devising, even though he totally could make everyone adequate if he so chose, such a god is an evil sadist

That wouldn't be called a test. That would be perfect beings who follow the commands of god. (which already exist and are called angels)

> It'd be like making up rules for what constitutes an evil pixel in Conway's game of life and punishing those pixels for their transgressions. You controlled every parameter.

If we set the rules and command those pixels you to follow the rules otherwise we punish you. And those pixels had free will but still chose to transgress. Wouldn't be fair to punish them?

> Those pixels failed the test because you set them up for preordained failure.

You have free will. You chose to transgress and revoke god even though the signs were obvious. God knows the outcome because he is all-knowing but you now have the freedom to do whatever you want. Your actions are not forced.