Sandbox test setup for redis

Should not we summon @whatyouhide here?

I am thinking about something that would make it possible to write tests like

test "redix_interop" do
  assert_redix_set "foo", 42, fn -> send(MyProcess, {:foo, 42}) end
  assert_redix_change, "bar", 3, fn -> MyModule.update_bars(& &1 + 3) end
  assert_redix ...
end