Python Code Help Debug Please

Code:

class Order:

def __init__(self):

self.wheels= {}

def add_wheels(self, wheel, number):

if wheel in self.wheels:

self.wheels[wheel] += number

else:

self.wheels[wheel] = number

def remove_wheels(self, wheel):

self.wheels.pop(wheel, 'None')

def count_unique_wheels(self):

return len(self.wheels.keys())

def count_total_wheels(self):

count=0

for value in self.wheels.values():

count += value

return count

def count_unique_material(self):

material_dict= {}

count=0

for key in self.wheels:

if key.material in material_dict:

continue

else:

material_dict[key.material] = 1

count += 1

return count

def count_wheels_with_material(self, material):

count=0

for wheel in self.wheels:

if wheel.material==material:

count += 1

return count

def get_cost(self):

cost = 0

for wheel in self.wheels:

cost += wheel.get_cost()*self.wheels[wheel]

return cost

def __str__(self):

return str(self.count_total_wheels())+" Wheels, cost: $" + str(round(self.get_cost()/100.0, 2))

Errors:

Traceback (most recent call last):

File "tester6p.py", line 471, in test_Order_02

self.assertEqual(str(o), '0 Wheels, cost: $0.00')

AssertionError: 'None Wheels, cost: $0.0' != '0 Wheels, cost: $0.00'

- None Wheels, cost: $0.0

? ^^^^

+ 0 Wheels, cost: $0.00

? ^ +

======================================================================

FAIL: test_Order_03 (__main__.AllTests)

----------------------------------------------------------------------

Traceback (most recent call last):

File "tester6p.py", line 516, in test_Order_03

self.assertEqual(str(o), '0 Wheels, cost: $0.00')

AssertionError: 'None Wheels, cost: $0.0' != '0 Wheels, cost: $0.00'

- None Wheels, cost: $0.0

? ^^^^

+ 0 Wheels, cost: $0.00

? ^ +

Test case:

def test_Order_03(self): CI-Cylinder(1,1) c2Cylinder (2,1) c3Cylinder (30,5) c4Cylinder (47,5) m1 = Material(1,"Tin") m2 = Material(75,"Silver") m3 Material (217, "Gold") m4 = Material(10000, "Magic") w1-Wheel (c1, c2, m1) w2 Wheel (cl, c2, m2) w3 Wheel (c3, c4, m3) w4-Wheel (c3, c4, m4) w5 Wheel (c1, c2, m4) oOrder() self.assertEqual (str(o), '0 Wheels, cost: $0.00') o.add wheels (w1, 2) self.assertEqual(str(o), '2 Wheels, cost: $0.01') _wheels (w1) 0. remove self.assertEqual (str(o), '0 Wheels, cost: $0.00') o.add_wheels (w2, 3) self.assertEqual(str(o), '3 Wheels, cost: $0.75) o.add_wheels (w2, 2) self.assertEqual(str(o), '5 Wheels, cost: $0.75) o.add wheels (w3, 2) self.assertEqual(str(o), '7 Wheels, cost: $24.62) o.remove wheels (w2) self.assertEqual(str(o), '2 Wheels, cost: $23.87) o.add_wheels (w4, 1) self.assertEqual (str(o), "3 Wheels, cost: $623.871 o.add_wheels (w5, 1000) self.assertEqual (str(o), '1003 Wheels, cost: $923.87)