This is a terrible function name. Does it check that the reverse of the test case that is passed also passes? No.

What makes sense would be something like given A and B, test that the reverse of A is B, the reverse of B is A, the double reverse of A is A and the double reverse of B is B.

This only depends on the flags. So that belong is the flag grilling test not in some common function.

dito

What about you define a set of flags, or even a function to get a selection of flags, and have the caller do something like

for (uint32_t flags : GetWhateverFlags()) {
    // Do stuff here...
}

and then delete that thing.

Just use a good old for loop. Bonus point, you'll be able to allocate one vector instead of n, the code will be easier to debug and follow in general and it's not even a given that it'll be that much longer.

For the many flag test, it's okay to use static test vectors, or to leverage GetTheThingYouWant() functions. Pick a pseudorandom set of flags, pick static and radom test vector, check that and do it again with a new set of flags.

This is not a good name. You can also drop the reverse test case thing and just pass two values.

Dude, just do

for (int i = 0; i < 4096; i++) {
    uint32_t flags = lcg.next();

    // Do stuff...
}

Just stop overcomplicating everything. This is not shorter, this is not faster (in fact, this is slower). Why does this exist? Also, bonus point for the Flag*Set* being a vector XD

Just create a test case with all the flag instead of woving this all over the place.

This has the same structure as op_reversebytes_iota_random_flags and op_reversebytes_palindrome so you should probably merge them. The code is talking to you, you just got to pay attention.

Don't create function if you are going to only use them in one place.

You can merge that into op_reversebytes_manual_random_flags with op_reversebytes_empty_stack_random_flags and maybe other pieces that I'm missing.