def test_humanize_type():
assert type(humanize("0")) is str
def test_humanize_number():
assert humanize("122") == "one hundred twenty two"
def test_humanize_long():
assert humanize(
"1 + 2 - 3 + 4 - 5 = 6 * 7 / 8"
) == "one plus two minus three plus four minus five equals six multiply by seven divide by eight"
def test_humanize_spaces():
assert humanize(" 1 * 1 = 20 - 1 9 "
) == "one multiply by one equals twenty minus nineteen"
def test_humanize_wrong_symbols():
assert humanize(" ^ . ") == "invalid input"
def test_humanize_symbols():
assert humanize("1+=") == "invalid input"
def test_humanize_common():
assert humanize("1 + 1 = 2") == "one plus one equals two"