$ perl test.pl
ok 1 - 9 .. 10 - 1 without constant (OP)
ok 2 - 9 .. 10 - 1 with constant() (OP)
not ok 3 - 9 .. 10 - 1 with constant (OP)
#   Failed test '9 .. 10 - 1 with constant (OP)'
#   at test.pl line 38.
#     Structures begin differing at:
#          $got->[1] = '10'
#     $expected->[1] = Does not exist
ok 4 - 9 .. 10 - 1 with constant() and parnes (proposed-me)
not ok 5 - 9 .. 10 - 1 with constant and parens (proposed-me)
#   Failed test '9 .. 10 - 1 with constant and parens (proposed-me)'
#   at test.pl line 60.
#     Structures begin differing at:
#          $got->[1] = '10'
#     $expected->[1] = Does not exist
ok 6 - 9 .. 10 - 1 with constant() (proposed-11143893)
ok 7 - 9 .. 10 - 1 with constant (proposed-11143893)
ok 8 - 9 .. 10 - 1 with constant() and parens (proposed-11143893/me)
ok 9 - 9 .. 10 - 1 with constant and parens (proposed-11143893/me)
ok 10 - 9 .. 10 with constant (OP)
ok 11 - 9 .. 10 with constant (proposed-11143893)
1..11
# Looks like you failed 2 tests of 11.