def test_subtract_given_addition_given_addition_to_string():
""". Tree node class str."""
tree = Sub(Sub(Leaf(5), Leaf(6)), Sub(Leaf(5), Leaf(6)))
assert tree.__str__() == "(5 - 6) - (5 - 6)"
def test_subtraction_with_leaves_to_class_string():
"""."""
print(Sub(Leaf(5), Leaf(6)).class_str())
assert eval(Sub(Leaf(5), Leaf(6)).class_str()).apply() == -1
def test_subtraction_with_leaves_to_string():
"""."""
tree = Sub(Leaf(5), Leaf(6))
assert tree.apply() == -1
assert tree.__str__() == "5 - 6"
def test_subtract_subtracts_when_given_leaves_with_numbers():
"""."""
assert Sub(Leaf(5), Leaf(6)).apply() == -1