Python Unit Test Automation

Listing 2-3.  test_module03.txt
>>> from test_module02 import *
>>> mul(2, 3)
6
>>> mul('a', 2)
'aa'
>>> add(2, 3)
5
>>> add('a', 'b')
'ab'

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You can run this test in the usual way, by running the following command in the 
command prompt:
python3 -m doctest -v test_module03.txt
The output will be as follows:
Trying:
    from test_module02 import *
Expecting nothing
ok
Trying:
    mul(2, 3)
Expecting:
    6
ok
Trying:
    mul('a', 2)
Expecting:
    'aa'
ok
Trying:
    add(2, 3)
Expecting:
    5
ok
Trying:
    add('a', 'b')
Expecting:
    'ab'
ok
1 items passed all tests:
   5 tests in test_module03.txt
5 tests in 1 items.
5 passed and 0 failed.
Test passed.
Advantages and Disadvantages of doctest
As you have learned, doctest is a very simple and intuitive framework for novice-level 
testing in Python. It does not require any installation and you can quickly get started with 
it without needing to know any API. It is mostly used for the following purposes:
•  To verify if the code documentation is up to date and the 
interactive examples in the docstring still work after making 
changes to the code.
•  To perform module-wise basic regression testing.

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•  To write illustrative tutorials and documentation that doubles as 
the test case for the package and module.
However, doctest has its own set of limitations. It does not have true API for testing. 
Also doctest tests tend to be static in nature and cannot be parameterized.
Readers are advised to visit the doctest documentation page at 
https://docs.
python.org/3/library/doctest.html
 for detailed usage and more examples.
Conclusion
In this chapter, you learned the basics of software testing. You explored a light testing 
framework, called doctest. It’s a good module for simple projects for novice Python 
users. However, due to its lack of advanced features like testrunner, test discovery, and 
test fixtures, doctest is not used in large projects. In the next chapter, we will discuss a 
built-in xUnit style test automation framework for Python, called unittest.

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© Ashwin Pajankar 2017 
A. Pajankar, Python Unit Test Automation, DOI 10.1007/978-1-4842-2677-3_3