> For example. I want to write test like this:
>
> @unittest.skip("This test requires huge memory")

There is @test.support.bigmemtest(size=_2G, memuse=1) decorator which
is more convinient than the skip decorators. See
Lib/test/test_bigmem.py.

You can use tracemalloc to get the memory peak:
tracemalloc.get_traced_memory()[1] is the peak.