Further Testing

Question 1

What are invariants

Answer 1

Assertions about classes/objects that should not change

Invariants should always be true

Question 2

Give advantages of test-driven development

Answer 2

Helps you design your code better
You see code from the user’s perspective not the developer’s

If your class is very difficult to test, then you should modify your design

Question 3

What are test suites used for

Answer 3

To test multiple classes to run as a single batch

Also, allow us to run a specific subset of unit tests from multiple test classes

Question 4

How do you implement mock objects

Answer 4

Implement an interface for production code

Implement the interface in a mock object for unit testing

Question 5

Give 3 uses of mock objects

Answer 5

When the real object:

has non-deterministic behaviour
is difficult to set up
has behaviour that is hard to trigger
is slow
has a user interface
doesn't exist yet

Question 6

What is a mock object

Answer 6

Sometimes we need to test an object but it’ll rely on other objects, mock objects are placeholder objects that allow testing of this method