def test_pop():
colors = SingleLinkedList()
colors.push("Magenta")
colors.push("Alizarin")
assert colors.pop() == "Alizarin"
assert colors.pop() == "Magenta"
assert colors.pop() == None
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
def test_get():
colors = SingleLinkedList()
colors.push("Vermillion")
assert colors.get(0) == "Vermillion"
colors.push("Sap Green")
assert colors.get(0) == "Vermillion"
assert colors.get(1) == "Sap Green"
colors.push("Cadmium Yellow Light")
assert colors.get(0) == "Vermillion"
assert colors.get(1) == "Sap Green"
assert colors.get(2) == "Cadmium Yellow Light"
assert colors.pop() == "Cadmium Yellow Light"
assert colors.get(0) == "Vermillion"
assert colors.get(1) == "Sap Green"
assert colors.get(2) == None
colors.pop()
assert colors.get(0) == "Vermillion"
colors.pop()
assert colors.get(0) == None
