def test_mergeLists_three(new_ll_iter, empty_new_list):
"""tests empty list in second position merges correctly"""
a = new_ll_iter
b = empty_new_list
mergeLists(a, b)
assert a.head._next._next.val is 3
def test_mergeLists_two(new_ll_iter, new_ll_iter_two):
"""tests two populated lists merge correcly"""
a = new_ll_iter
b = new_ll_iter_two
mergeLists(a, b)
assert a.head._next._next._next.val is 6
def test_mergeLists_one(empty_new_list, new_ll_iter):
"""tests empty list in first position and populated list merge correcly"""
a = empty_new_list
b = new_ll_iter
mergeLists(a, b)
assert a.head._next._next.val is 3
def test_mergeLists_xempty(empty_ll, n_linked_ll):
"""test for merging with empty list as first list """
mergeLists(empty_ll, n_linked_ll)
assert str(empty_ll) == str([1, 2, 3])
def test_mergeLists_dif_len(linked_list_zip, n_linked_ll):
""" test for merge like zip """
mergeLists(linked_list_zip, n_linked_ll)
assert str(linked_list_zip) == str([9, 1, 8, 2, 7, 3, 6])
def test_mergeLists_yempty(empty_ll, n_linked_ll):
"""test for merging with empty list as second list """
mergeLists(n_linked_ll, empty_ll)
assert str(n_linked_ll) == str([1, 2, 3])