def test_last():
colors = SingleLinkedList()
colors.push("Cadmium Red Light")
assert colors.last() == "Cadmium Red Light"
colors.push("Hansa Yellow")
assert colors.last() == "Hansa Yellow"
colors.shift("Pthalo Green")
assert colors.last() == "Hansa Yellow"
def test_shift():
colors = SingleLinkedList()
colors.shift("Cadmium Orange")
assert colors.count() == 1
colors.shift("Carbazole Violet")
assert colors.count() == 2
assert colors.pop() == "Cadmium Orange"
assert colors.count() == 1
assert colors.pop() == "Carbazole Violet"
assert colors.count() == 0
