Integration testing for part of function

I'm trying to find a pattern which will allow me to test part of the functionality of my main() function:

def main():
  do_a()
  download_file()
  do_b()
  do_c()
  do_d()

I'd like to have a test that asserts that the flow up until (and including) the download_file is working correctly.

One obvious way to do so would be to pass a test_name as a parameter and have a logic like:

if test_name == 'download_file':
  return 

but I'd like to avoid mixing testing logic inside production code.

Another option would be to mock the functions do_b, do_c, and do_d but then if there are lots like so, it's neither elegant nor maintainable to mock all of them.

Thanks for any insight.