I'd like to see some checks for cases with several adjacent separators, with max varying so as to end before, within and after a group of repeat separators, e.g. ":one::two:::three"/':' with max = 3, 4, 5, 6.
I'd also like to see some tests that use actual regex, not simple single character separators, e.g. split the preceding with ":+" and verify you get { "one", "two", "three" }.
I'd like to see some tests with more-than-one-character strings, e.g. split on "=>", and some cases with cases of overlapping delimiters, e.g. split on "--" (c.f. XML comments) when the string has "---" somewhere in it.