Can't call child class method from parent class

I was wondering if someone can tell me the error. Why I can’t access the child class method from the parent class. Thank you!

Code is about a game where we have a soldier and his inventory. I try to call Soldier().add_weapon but it returns an error that no add_weapon exists for Soldier

Code:

class Soldier():
    def __init__(self, name, price, health=100, kills=0, type='human'):

        assert price >= 0 
        assert health >= 0 
        assert kills >= 0
        assert type is 'human' or 'air' or 'ground'
        #assert inventory 

        self.name = name
        self.price = price
        self.health = health
        self.kills = kills
        self.type = type

    @property
    def get_name(self):
        return self._name

    @get_name.setter
    def set_name(self, value):
        self._name = value

    def get_health(self):
        return self.health

    def set_health(self, value):
        self.health = value

    def face_damage(self, value):
        self.health = self.health - int(value)

    def is_alive(self):
        if self.health > 0:
            return True
        else:
            return False

    def get_inventory(self):
        pass

class Inventory(Soldier):

    def __init__(self):

        super().__init__(
            
        )
    
        self.inv = []
    
    def add_weapon(self, item):
        
        if item not in self.inv:

            self.inv.append(item)
        
        else: None

    def get_total_attack(self, weapon_specs = {
     'rifle': {'air': 1, 'ground': 2, 'human': 5},
     'pistol': {'air': 0, 'ground': 1, 'human': 3},
     'rpg': {'air': 5, 'ground': 5, 'human': 3},
     'warhead': {'air': 10, 'ground': 10, 'human': 10},
     'machine gun': {'air': 3, 'ground': 3, 'human': 10}
     }):
     
        damages = {}
        for weapon in self.inv:
            for k,v in weapon_specs[weapon].items():
                damages[k] = damages.get(k, 0) + v
        
        return damages

    '''
    def get_inventory(self):
        for x in self.inv:
            return x
    '''

    def attack(self, value, total):
        for i in self.inv:
            for k in total:
                return total[k]
        


def test_p2_4():
  soldier = Soldier('ranger', 100)
  soldier.add_weapon('rifle')
  soldier.add_weapon('machine gun')
  soldier.add_weapon('rpg')
  inventory = soldier.get_inventory()
  damages = inventory.get_total_attack()
  correct = damages['air'] == 9 and damages['ground'] == 10 and damages['human'] == 18
  assert correct
  return "Passed!"


print(test_p2_4())

Error I get
:

AttributeError: ‘Soldier’ object has no attribute ‘add_weapon’

>Solution :

The way you’ve written your code, an Inventory is a type of Soldier, which doesn’t make sense. Instead, a Soldier should have an Inventory:

class Soldier:
    def __init__(self, name, price, health=100, kills=0, soldier_type='human'):

        assert price >= 0
        assert health >= 0
        assert kills >= 0
        assert soldier_type in ('human', 'air', 'ground')
        self.name = name
        self.price = price
        self.health = health
        self.kills = kills
        self.type = soldier_type
        self.inventory = Inventory()

    @property
    def get_name(self):
        return self._name

    @get_name.setter
    def set_name(self, value):
        self._name = value

    def get_health(self):
        return self.health

    def set_health(self, value):
        self.health = value

    def face_damage(self, value):
        self.health = self.health - int(value)

    def is_alive(self):
        if self.health > 0:
            return True
        else:
            return False

    def get_inventory(self):
        return self.inventory


class Inventory:

    weapon_specs = {
        'rifle': {'air': 1, 'ground': 2, 'human': 5},
        'pistol': {'air': 0, 'ground': 1, 'human': 3},
        'rpg': {'air': 5, 'ground': 5, 'human': 3},
        'warhead': {'air': 10, 'ground': 10, 'human': 10},
        'machine gun': {'air': 3, 'ground': 3, 'human': 10}
    }

    def __init__(self):
        self.inv = set()

    def add_weapon(self, item):
        # No need to dedupe since we made this a set instead of a list.
        self.inv.add(item)

    def get_total_attack(self):
        damages = {}
        for weapon in self.inv:
            for k, v in self.weapon_specs[weapon].items():
                damages[k] = damages.get(k, 0) + v
        return damages

    def get_inventory(self):
        return self.inv

    def attack(self, total):
        # not sure what this is actually supposed to do, but this
        # is the closest approximation of what your code was TRYING to do?
        return total.values()


def test_p2_4():
    soldier = Soldier('ranger', 100)
    inventory = soldier.get_inventory()
    inventory.add_weapon('rifle')
    inventory.add_weapon('machine gun')
    inventory.add_weapon('rpg')
    damages = inventory.get_total_attack()
    assert damages['air'] == 9 and damages['ground'] == 10 and damages['human'] == 18
    return "Passed!"


print(test_p2_4())