Midterm Review Question Answers

Part A:   1. a     2. b   3. d   4. c   5. c
          6. a,d   7. b   8. b   9. a  10. c
         11. b    12. b  13. a  14. a
         
Part B:  The order of the operators from highest priority on the left
         to lowest priority on the right is:
         
         ( )   [ ]    .    **    *     +     ==    and    =
         
Part C: Correct the errors

See the error log below.

Corrected Script:

 1 # --- Source code file vendingmachine.py -------------------

 2 # This vending machine dispenses one type of
 3 # candy bar, which is paid for with 3 quarters.

 4 class VendingMachine:

 5     def __init__(self):
 6         self._num_candy_bars = 3
 7         self._num_quarters = 0
 8     def insert_quarter(self):
 9         self._num_quarters += 1
10         return "Quarter inserted."

11     def dispense_candy_bar(self):
12         if self._num_quarters >= 3 and \
13             self._num_candy_bars > 0:
14             self._num_quarters = 0
15             self._num_candy_bars -= 1
16             return "Candy bar dispensed."
17         else:
18             return "VM out of candy bars."
19     def __str__(self):
20         return f"{self._num_candy_bars} " + \
21             f"{self._num_quarters}"

22 # --- Source code file: test1.py ---------------------
23 from vendingmachine import VendingMachine

24 vm = VendingMachine( )
25 print(vm)
26 print( )
27 print(vm.insert_quarter( ))
28 print(vm)
29 print(vm.insert_quarter( ))
30 print(vm.insert_quarter( ))
31 print(vm.dispense_candy_bar( ))
32 print(vm)

33 for i in range(0, 3):
34     print( )
35     for j in range(0, 3):
36         print(vm.insert_quarter( ))
37     vm.dispense_candy_bar( )
38     print(vm)

Error Log:
Line 4: Change vendingmachine to VendingMachine.
Line 5: Add colon at the end of line.
Line 6: Change == to =.
Line 7: Add self. to beginning of line.
Line 9: Remove space between + and = to make +=.
Line 11: Change dashes to underscores and change ( ) to (self).
Line 17: Add colon to end of line.
Line 21: Add f to beginning of line.
Line 24: Remove new from line.
Line 33: Replace colon by comma, add colon to end of line.
Line 34: Add ( ) to end of line.
Line 36: Replace self by vm.
Line 37: Add vm. to beginning of line.

Part D: Predict the Output

Output from test1.py

Ford Silver
35
0
False

Part D: Convert Traditional Test to Unit Test.

To convert a traditional test script to a unit test script,
just replace print statements by assertEqual statements.
Leave the other statements as is.

# test2.py script:
from automobile import Automobile
import unittest

class MyUnitTestClass(unittest.TestCase):
        
    def test_1(self):
    
        # Sample assertEqual statement: 
        # self.assertEqual(computed, expected)
        
        from automobile import Automobile

        auto = Automobile("Ford", "Silver")
        self.assertEqual(str(auto), "Ford Silver")
        auto.turn_key("on")
        auto.shift("Drive")
        auto.press_accelerator(20)
        auto.press_accelerator(15)
        self.assertEqual(auto.speed, 35)
        auto.press_brake(40)
        self.assertEqual(auto.speed, 0)
        auto.turn_key("off")
        self.assertEqual(auto.is_running, False)
        
if __name__ == '__main__':
    unittest.main( )

# Output:
.
---------------------------------------------------------
Ran 1 test in 0.015s

OK