@pytest.fixture
def linear_structure(request, graph, random_sequence):
 sequence = random_sequence()
 graph.consume(sequence)
 if hdn_counts(sequence, graph):
  request.applymarker(pytest.mark.xfail)
 return (graph, sequence)

@ pytest . fixture def linear_structure ( request , graph , random_sequence ) : sequence = random_sequence ( ) graph . consume ( sequence ) if hdn_counts ( sequence , graph ) : request . applymarker ( pytest . mark . xfail ) return ( graph , sequence )
sets up a simple linear path graph structure .