add more tests to increase coverage
add more tests to increase coverage

See https://coveralls.io/builds/2452816/source?filename=src%2Fnpge%2Fcpp%2FgoodSlices.cpp#L171

npge/lua-npge,npge/lua-npge,starius/lua-npge,starius/lua-npge,starius/lua-npge,npge/lua-npge