Python Unit Test Automation

Figure 4-4.  A rednose demo

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•  nose has more fixtures than unittest. In addition to the regular 
unittest fixtures, nose has package- and function-level fixtures.
•  nose has alternate names for fixtures.
•  nose.tools offers many features for automating test cases.
•  Test discovery is simpler in nose than in unittest, as nose does 
not need a Python interpreter with the discover sub-command.
•  nose can recognize and run unittest tests easily.
Disadvantages of nose
The only and the biggest disadvantage of nose is that it is not under active development 
and has been in maintenance mode for the past several years. It will likely cease without 
a new person or team to take over its maintenance. If you’re planning to start a project 
and are looking for a suitable automation framework for Python 3, then pytest, nose2, or 
plain unittest.
You might be wondering why I even spent time covering nose if it is not being 
actively developed. The reason is that learning a more advanced framework like nose 
helps you understand the limitations of unittest. Also, if you are working with an older 
project that uses nose as the test automation and/or unit testing framework, it will help 
you understand your tests.
Using Nose 2
nose2 is the next generation of testing for Python. It is based on the plugins branch of 
unittest2.
nose2 aims to improve on nose as follows:
•  It provides a better plugin API.
•  It is easier for users to configure.
•  It simplifies internal interfaces and processes.
•  It supports Python 2 and 3 from the same codebase.
•  It encourages greater community involvement in its development.
•  Unlike nose, it is under active development.
It can be installed conveniently using the following command:
sudo pip3 install nose2
Once installed, nose2 can be invoked by running nose2 at the command prompt.  
It can be used to auto-discover and run the unittest and nose test modules. Run 
the nose2 -h command at the command prompt to get help with the various nose2 
command-line options.

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The following are the important differences between nose and nose2:
•  Python versions
nose supports Python version 2.4 and above. nose2 supports 
pypy, 2.6, 2.7, 3.2, 3.3, 3.4, and 3.5. nose2 does not support all the 
versions, as it is not possible to support all the Python versions in 
a single codebase.
•  Test loading
nose loads and executes test modules one by one, which is called 
lazy loading. On the contrary, nose2 loads all the modules first 
and then executes them all at once.
•  Test discovery
Because of the difference between the test loading techniques, 
nose2 does not support all the project layouts. The layout shown 
in Figure 
4-5
 is supported by nose. However, it will not be loaded 
correctly by nose2. nose can distinguish between ./dir1/test.
py and ./dir1/dir2/test.py.