Multiple Choice Questions

Exercises 20.10 Multiple Choice Questions

1.

Q-1: Given the below code, what would be printed (ignore newlines and spacing between sentences)?

class Person:
    def work(self):
        print("A person can work.")

    def food(self):
        print("A person eats food.")

class Employee(Person):
    def work(self):
        print("An employee works.")

p1 = Person()
p2 = Employee()
p1.work()
p2.work()
p1.food()
p2.food()

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A person can work. A person can work. An employee works. A person eats food.
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Try again!
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A person can work. An employee works. A person eats food.
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Try again!
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The code won't compile.
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Try again!
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A person can work. An employee works. A person eats food. A person eats food.
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Correct! Since Employee inherited from Person, the food method works for the Employee class as well.
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A person can work. A person can work. An employee works. A person eats food. A person eats food.
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Try again!

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2.

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Q-2: Given the below code, what would be printed (ignore newlines and spacing between sentences)?

class Person:
   def work(self):
      print("A person can work.")

   def food(self):
      print("A person eats food.")

class Employee(Person):
   pass

p1 = Person()
p2 = Employee()
p1.work()
p2.work()
p1.food()
p2.food()

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A person can work. None. A person eats food. None.
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Try again!
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A person can work. A person can work. A person eats food. A person eats food.
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Correct! Since Employee inherited from Person, the methods work and food work for Employee as well.
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The code won't compile.
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Try again!
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A person can work. A person eats food.
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Try again!

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3.

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Q-3: Given the below code, what would be printed (ignore newlines and spacing between sentences)?

class Person:
   def work(self):
      print("A person can work.")

   def food(self):
      print("A person eats food.")

class Employee(Person):
   def work(self):
      super().work()
      print("I can work.")

   def food(self):
      super().food()
      print("I can eat.")

p1 = Person()
p2 = Employee()
p1.work()
p2.work()
p1.food()
p2.food()

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A person can work. I can work. A person eats food. I can eat.
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Try again! There are 2 sentences missing: "A person can work." and "A person eats food.".
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A person can work. None. I can work. A person eats food. None. I can eat.
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Try again! Using super().method in the child class Employee method inherits the method (print statements, in this case) from the parent class Person.
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The code won't compile.
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Try again! The code compiles.
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A person can work. A person can work. I can work. A person eats food. A person eats food. I can eat.
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Correct! Using super() reduces code duplication, and the child class method can duplicate the functionality of the parent class method.

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4.

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Q-4: For which of the following can inheritance be used?

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Keyboard inherits from Computer.
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Try again! Keyboard isn't a type of Computer, so inheritance can't be used.
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Student inherits from Person.
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Correct! Student is a type of Person, so inheritance can be used.
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Encyclopedia inherits from Book.
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Correct! Encyclopedia is a type of Book, so inheritance can be used.
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Person inherits House.
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Try again! Person isn't a type of House, so inheritance can't be used.

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5.

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Q-5: Can a class only inherit from another class if it is a type of the class?

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Yes, a class can only inherit from another class if it is a type of the class.
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Correct! A class can only inherit from another class if it is a type of the class. For example, an encyclopedia is a type of book.
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No, a class can inherit from another class if they're associated.
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Try again!
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Yes and no. A class can inherit from another class if they're associated or if it is a type of the class.
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Try again!

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6.

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Q-6: What phrases represent inheritance?

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A (class) has a (class).
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Try again! Classes that are associated can't use inheritance.
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A (class) can be substituted with (another class).
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Correct! Classes that can be substituted can use inheritance.
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A (class) can be associated with (another class).
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Try again! Classes that are associated can't use inheritance.
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A (class) is a type of (other class).
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Correct! Classes that can be substituted can use inheritance.
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A (class) is a specialization of (other class).
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Correct! Classes that can be substituted can use inheritance.

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7.

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Q-7: How do you call a method in a parent class?

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parent().method
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Do not use parent.
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parent.method
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Do not use parent. Do use ().
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super().method
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Correct! Use super().method to call parent class methods.
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super.method
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You need the ()

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8.

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Q-8: If Dictionary is a subclass of Book, what line of code is needed to invoke the __init__ method in Book to Dictionary?

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Book.__init__(self)
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Correct! Using ParentClass.method is one way to invoke a method in the ParentClass to the ChildClass.
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Dictionary.__init__(self)
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Try again!
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super().__init__()
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Correct! Using super().method is one way to invoke a method in the ParentClass to the ChildClass.
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Book.super().__init__(self)
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Try again!
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Book.__init__(Dictionary)
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Try again!

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9.

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Q-9: What will be printed?

class Person:
   pass

class Employee(Person):
   pass

p2 = Employee()
print(isinstance(p2, Person))

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True
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Correct! p2 is assigned to an Employee object, and the Employee object inherits from Person. Therefore, p2 is an instance of Person.
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False
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Try again!
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The code won't compile.
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Try again! The code compiles even with the pass statements.
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None
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Try again! Printing isinstance() will print either True or False if it compiles.

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10.

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Q-10: Which statement about inheritance is incorrect?

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Inheritance is a key idea of Object-oriented programming (OOP).
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Try again! This statement about inheritance is correct.
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The child class is also called a subclass or a derived class.
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Try again! This statement about inheritance is correct.
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Private members of a class can be inherited.
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Correct! This statement about inheritance is incorrect. Private members of a class can't be inherited.
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Protected members of a class can be inherited.
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Try again! This statement about inheritance is correct.

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11.

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Q-11: Given that there is an Item class with a name and price with a __str__ method that returns "name: price", which of the following is correct?

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I

class TestItem(unittest.TestCase):

    def setUp():
        i1 = Item("Coke", 2.99)
        i2 = Item("Burger", 6.99)

    def test_str_item():
        self.assertEqual(i1.__str__(), "Coke: 2.99")
        self.assertEqual(i2.__str__(), "Burger: 6.99")

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II

class TestItem(unittest.TestCase):

    def setUp(self):
        self.i1 = Item("Coke", 2.99)
        self.i2 = Item("Burger", 6.99)

    def test_str_item():
        self.assertEqual(i1.__str__(), "Coke: 2.99")
        self.assertEqual(i2.__str__(), "Burger: 6.99")

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III

class TestItem(unittest.TestCase):

    def setUp(self):
        self.i1 = Item("Coke", 2.99)
        self.i2 = Item("Burger", 6.99)

    def test_str_item(self):
        self.assertEqual(self.i1.__str__(), "Coke: 2.99")
        self.assertEqual(self.i2.__str__(), "Burger: 6.99")

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IV

class TestItem(unittest.TestCase):

    def setUp():
        i1 = Item("Coke", 2.99)
        i2 = Item("Burger", 6.99)

    def test_str_item(self):
        self.assertEqual(self.i1.__str__(), "Coke: 2.99")
        self.assertEqual(self.i2.__str__(), "Burger: 6.99")

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I
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All methods take self (the current object).
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II
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The test_create method takes self and you must use self to access i1 and i2.
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III
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Correct! Remember to pass in self to methods and use self when accessing attributes.
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IV
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The setUp method takes self and you must use self in the setUp so other methods will still have access.

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12.

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Q-12: Given that there is an Car class with attributes of make and color, which of the following is correct?

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I

class TestCar(unittest.TestCase):

    def setUp():
         c1 = Car("Ford", "blue")
         c2 = Car("Toyota", "red")

     def test_create_car():
         assertEqual(c1.make, "Ford")
         assertEqual(c1.color, "blue")
         assertEqual(c2.make, "Toyota")
         assertEqual(c2.color, "red")

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II

class TestCar(unittest.TestCase):

    def setUp(self):
        self.c1 = Car("Ford", "blue")
        self.c2 = Car("Toyota", "red")

    def test_create_car(self):
        assertEqual(self.c1.make, "Ford")
        assertEqual(self.c1.color, "blue")
        assertEqual(self.c2.make, "Toyota")
        assertEqual(self.c2.color, "red")

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III

class TestCar(unittest.TestCase):

    def setUp(self):
        self.c1 = Car("Ford", "blue")
        self.c2 = Car("Toyota", "red")

    def test_create_car():
        self.assertEqual(self.c1.make, "Ford")
        self.assertEqual(self.c1.color, "blue")
        self.assertEqual(self.c2.make, "Toyota")
        self.assertEqual(self.c2.color, "red")

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IV

class TestCar(unittest.TestCase):

    def setUp(self):
        self.c1 = Car("Ford", "blue")
        self.c2 = Car("Toyota", "red")

    def test_create_car(self):
        self.assertEqual(self.c1.make, "Ford")
        self.assertEqual(self.c1.color, "blue")
        self.assertEqual(self.c2.make, "Toyota")
        self.assertEqual(self.c2.color, "red")

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I
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All methods take self (the current object).
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II
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The assertEqual methods need to be called on self (the current object).
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III
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All methods take self (the current object).
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IV
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Correct! All methods take self and you must call assertEqual on self and use self for accessing attributes.

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13.

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Q-13: Given that there is an Car class with attributes of make and color and a method set_color which changes the color, which of the following is correct?

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I

class TestCar(unittest.TestCase):

    def setUp():
         c1 = Car("Ford", "blue")
         c2 = Car("Toyota", "red")

     def test_change_color():
         assertEqual(c1.color, "blue")
         c1.set_color("yellow")
         assertEqual(c1.color, "yellow")
         assertEqual(c2.color, "red")
         c2.set_color("blue")
         assertEqual(c2.color, "blue")

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II

class TestCar(unittest.TestCase):

    def setUp(self):
         self.c1 = Car("Ford", "blue")
         self.c2 = Car("Toyota", "red")

     def test_change_color(self):
         self.assertEqual(self.c1.color, "yellow")
         self.c1.set_color("yellow")
         self.assertEqual(self.c1.color, "blue")
         self.assertEqual(self.c2.color, "red")
         self.c2.set_color("blue")
         self.assertEqual(self.c2.color, "blue")

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III

class TestCar(unittest.TestCase):

    def setUp(self):
         self.c1 = Car("Ford", "blue")
         self.c2 = Car("Toyota", "red")

     def test_change_color(self):
         self.assertEqual(self.c1.color, "blue")
         self.c1.set_color("yellow")
         self.assertEqual(self.c1.color, "yellow")
         self.assertEqual(self.c2.color, "red")
         self.c2.set_color("blue")
         self.assertEqual(self.c2.color, "blue")

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IV

class TestCar(unittest.TestCase):

    def setUp(self):
         self.c1 = Car("Ford", "blue")
         self.c2 = Car("Toyota", "red")

     def test_change_color(self):
         self.assertEqual(self.c1.color, "blue")
         self.c1.set_color("yellow")
         self.assertEqual(self.c1.color, "yellow")
         self.assertEqual(self.c2.color, "blue")
         self.c2.set_color("blue")
         self.assertEqual(self.c2.color, "red")

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I
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All methods take self (the current object).
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II
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Check the original and changed color on each car object.
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III
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Correct!
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IV
🔗
Check the original and changed color on each car object.

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14.

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Q-14: Given that there is an Car class with attributes of make and color and a method set_make which changes the make, which of the following is correct?

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I

class TestCar(unittest.TestCase):

    def setUp():
         c1 = Car("Ford", "blue")
         c2 = Car("Toyota", "red")

     def test_change_make():
         assertEqual(c1.make, "Ford"")
         c1.set_make("Toyota")
         assertEqual(c1.make, "Toyota")
         assertEqual(c2.make, "Toyota")
         c2.set_make("Ford")
         assertEqual(c2.make, "Ford")

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II

class TestCar(unittest.TestCase):

    def setUp(self):
         self.c1 = Car("Ford", "blue")
         self.c2 = Car("Toyota", "red")

     def test_change_make():
         self.assertEqual(self.c1.make, "Toyota")
         self.c1.set_make("Ford")
         self.assertEqual(self.c1.make, "Ford")
         self.assertEqual(self.c2.make, "Ford")
         self.c2.set_make("Toyota")
         self.assertEqual(self.c2.make, "Toyota")

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III

class TestCar(unittest.TestCase):

    def setUp(self):
         self.c1 = Car("Ford", "blue")
         self.c2 = Car("Toyota", "red")

     def test_change_make(self):
         self.assertEqual(c1.make, "Toyota")
         self.c1.set_make("Ford")
         self.assertEqual(c1.make, "Ford")
         self.assertEqual(c2.make, "Ford")
         self.c2.set_make("Toyota")
         self.assertEqual(c2.make, "Toyota")

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IV

class TestCar(unittest.TestCase):

    def setUp(self):
         self.c1 = Car("Ford", "blue")
         self.c2 = Car("Toyota", "red")

     def test_change_make(self):
         self.assertEqual(self.c1.make, "Ford"")
         self.c1.set_make("Toyota")
         self.assertEqual(self.c1.make, "Toyota")
         self.assertEqual(self.c2.make, "Toyota")
         self.c2.set_make("Ford")
         self.assertEqual(self.c2.make, "Ford")

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I
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All methods take self (the current object).
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II
🔗
All methods take self (the current object).
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III
🔗
Are the test cases correct? What was the original make and changed make for each?
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IV
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Correct!

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15.

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Q-15: Given that there is an Item class with a name and price and an Order class that takes a list of Item objects and has a total method which returns the total price for all items, which of the following is correct?

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I

class TestItem(unittest.TestCase):

    def setUp(self):
        i1 = Item("Coke", 2.99)
        i2 = Item("Burger", 6.99)
        self.o1 = Order([i1, i2])

    def test_create_order_total(self):
        self.assertAlmostEqual(self.o1.total(), 9.98, 2)

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II

class TestItem(unittest.TestCase):

    def setUp(self):
        i1 = Item("Coke", 2.99)
        i2 = Item("Burger", 6.99)
        self.o1 = Order([i1, i2])

    def test_create_order_total(self):
        self.assertAlmostEqual(self.o1.total(), 9.99, 2)

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III

class TestItem(unittest.TestCase):

    def setUp(self):
        i1 = Item("Coke", 2.99)
        i2 = Item("Burger", 6.99)
        self.o1 = Order([i1, i2])

    def test_create_order_total(self):
        self.assertAlmostEqual(self.o1.total(), "8.98", 2)

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IV

class TestItem(unittest.TestCase):
class TestItem(unittest.TestCase):

    def setUp(self):
        i1 = Item("Coke", 2.99)
        i2 = Item("Burger", 6.99)
        self.o1 = Order([i1, i2])

    def test_create_order_total(self):
        self.assertAlmostEqual(self.o1.total(), 8.98, 2)

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I
🔗
Correct!
🔗
II
🔗
Is 9.99 correct?
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III
🔗
The method total returns a number, not a string.
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IV
🔗
Is 8.98 correct?

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Exercises 20.10 Multiple Choice Questions

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