Take a look at the code for this simple class, and use it to figure out the answers to the questions. It's okay to check back through the book. This is just a way for you to make sure you're ready to move on:
class ClassOne:
def __init__(self, arg1, arg2):
self.arg1 = int(arg1)
self.arg2 = arg2
def method1(self, x):
return x * self.arg1
def method2(self, x):
return self.method1(self.arg2) * xHere are the questions:
- Assuming that we're using methods as units, how many units exist in the preceding code?
Answer: There are three units that exist in the preceding code and that are as follows:
__init__,method1, andmethod2.__init__is a method, just asmethod1andmethod2. The fact that it's a constructor means that it's all tangled up with the other units, but it's still a method containing code and a possible location for bugs, and so we cannot afford to treat this as anything other than a unit. - Which units make assumptions about the correct operation of other units? In other words, which units are not independent?
Answer: Both
method1andmethod2assume that__init__works right, andmethod2makes the same assumption as that ofmethod1. - How can you write a test for
method2that does not assume that other units work correctly?Answer: The tests for
method2will need to use a fakemethod1that is a part of the test code, and not a part of the code being tested.