add tests for list arguments

[doliv071]

Great package, really happy to see someone implementing this for R.

Would you be interested in adding list arguments to the set of tests? I understand this can get out of hand QUICKLY.

Here are a few that I wrote up while thinking about this. doesn't include nesting or listing of complex structures though.

listFuzz <- list(
    list_empty = list(),
    list_single = list(1),
    list_single_blank = list(" "),
    list_mult = list(1, 2, 3),
    list_mult_blank = list("", "", " ", " "),
    list_with_na = list(NA, 2, 3),
    list_single_na = list(NA),
    list_all_na = list(NA, NA, NA),
    list_var_len = list(c(1,2,3), c(1,2), c(1)),
    list_mix_vals = list(c(1,2,3), c("a", "b", "c")),
    list_named = list(A = c(1,2,3), B = c("a", "b", "c")),
    list_named_var_len = list(A = c(1,2,3), B = c(1,2), C = c(1)),
    list_named_na = list(A = NA, B = NA, C = NA),
    list_0len = list(character(0), integer(0)),
    list_named_0len = list(A = character(0), B = integer(0))
)```