def test_fitness_update():
"""
test fitness is updated when weight is changed
"""
animal = Herbivore(10, 50)
before_fitness = animal.fitness
animal.lose_weight()
assert animal.fitness != before_fitness
def test_animal_weight_loss():
"""
Test if animal looses weight
"""
animal = Herbivore(10, 50)
before_weight = animal.weight
animal.lose_weight()
assert before_weight > animal.weight