Test plan
naction   expected     comment
nincrement   1            increment from initial state
nincrement   2     sequence of increments
nincrement   3
nincrement   4
ndecrement   3               sequence of decrements
ndecrement   2
nincrement   3        increment follows decrement
nreset   0
nincrement   1      increment follows reset
ndecrement   0
ndecrement   0             decrement 0 count
nreset   0
ndecrement   0     decrement follows reset
ncreate   0     initial state
ndecrement   0           decrement from initial state