SUM test suite:
0 0 
97 1 a
16556 1 abc
26423 1 message digest
53553 1 abcdefghijklmnopqrstuvwxyz
54802 1 abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq
25587 1 ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
21845 1 12345678901234567890123456789012345678901234567890123456789012345678901234567890
62769 977 one million 'a' characters