Design Example: A vending machine
- Release item after receiving 15 cents
- Single coin slot for dimes (10 ¢) and nickels (5 ¢) - assuming sensor specifies coin type
- Machine does not give change
Draw state diagram by considering the below input sequences:
- 3 nickels
- 2 nickels, dime
- Nickel, dime
- Dime, nickel
- Two dimes
Inputs: N, D, reset Output: Open
What would change if, for example, the machine had the option to dispense two types of chocolate bar? There would be two buttons to choose a bar (say, one for Mars and one for Snickers) and the machine would give change.
- Suppose test suite A satisfies adequacy criterion C1. Test suite B satisfies adequacy criterion C2, and C2 subsumes C1. Can we be certain that faults revealed by A will also be revealed by B?
Yes. Subsumes is a synonym for includes and thus the tests in C2(B) include the tests in C1(A).