Test cases don't require Lancer input

I defined the Lancer class but never added any code for it to do anything. It never attacks the 2nd person in line, no modifications were made to my code from Vampire test except to add the Lancer class. Still it passes Check and gives me a Mission Clear.

My code for reference:

class Warrior:
    def __init__(self, *args, **kwargs):
        self.health = 50
        self.attack = 5
        self.defense = 0
        self.vampirism = 0
        self.cleave = 0
        self.is_alive = True
    pass

class Rookie(Warrior):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.attack = 1
    pass

class Knight(Warrior):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.attack = 7
    pass

class Defender(Warrior):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.health = 60
        self.attack = 3
        self.defense = 2
    pass

class Vampire(Warrior):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.health = 40
        self.attack = 4
        self.vampirism = 50
    pass

class Lancer(Warrior):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.attack = 6
        self.cleave = 50
    pass

class Army:
    def __init__(self, *args, **kwargs):
        self.units = []
    def add_units(self, type, amount):
        for i in range(amount):
            self.units.append(type())

class Battle:
    def fight(self, army1, army2):
        while len(army1.units) != 0 and len(army2.units) != 0:
            if fight(army1.units[0], army2.units[0]):
                army2.units.pop(0)
            else:
                army1.units.pop(0)
        if len(army1.units) == 0:
            return False
        else:
            return True

def damage(att, d):
    dam = att.attack - d.defense
    if dam < 0:
        dam = 0
    return dam

def vamp(att, d):
    res = (damage(att, d)*(att.vampirism/100))//1
    return res

def fight(unit_1, unit_2):
    while unit_1.is_alive and unit_2.is_alive:
        unit_2.health -= damage(unit_1, unit_2)
        unit_1.health += vamp(unit_1, unit_2)
        if unit_2.health > 0:
            unit_1.health -= damage(unit_2, unit_1)
            unit_2.health += vamp(unit_2, unit_1)
        else:
            unit_2.is_alive = False
        if unit_1.health <= 0:
            unit_1.is_alive = False
    return unit_1.is_alive