If there can be a "before" the known laws of physics, there can also be an "outside" of the known laws of physics. And if the universe has a Creator, one who actually created the whole of space and time and all the laws that science seeks to discover and understand, He must be in that "outside," since if He were "inside," He would not be the Creator, just as a statue cannot be its own sculptor.
How then do we "test" for Him? Perhaps by finding His fingerprints: the Anthropic Principle, evidence of design in life, communications with mankind that can be tested and authenticated, etc.
Oh, but I forgot: We're not allowed to even inquire in such directions. It's just not scientific--at least not according to the modern priests of atheism and humanism.
The “modern priests of atheism and humanism” set up the parameters of discussion (science/materialism) to exclude the Creator,
then state that they’ve disproved the Creator.
That’s not science, that’s dogma.
You set forth a possible observation, the results of which are not yet known, and set forth the test "Result X would indicate the absence of such an entity".
Ball's in your court....
No, but those tests and observations have led us to the Big Bang. And as theories develop and instruments get better, we’ll have even more evidence. And if the evidence and theory points to something else, that something else will take the place of the Big Bang.
But anyway, you are asking for mutually exclusive things, first you want to say that “God is outside observation” then you want to say “Traces of God is observable.”
You can’t have it both ways. If you want God to be a part of science, if He doesn’t exist following the rules of science, then you would have to admit God doesn’t exist.