Testing Python code using doctest

1 def multiply(x, y):
2     return x * y

 1 '''
 2 Module showing how doctests can be included with source code
 3 Each '>>>' line is run as if in a python shell, and counts as a test.
 4 The next line, if not '>>>' is the expected output of the previous line.
 5 If anything doesn't match exactly (including trailing spaces), the test fails.
 6 '''
 7 
 8 
 9 def multiply(x, y):
10     """
11     >>> multiply(4, 3)
12     12
13     >>> multiply('a', 3)
14     'aaa'
15     """
16     return x * y