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• How to test python code with pytest.
• How to mesure test coverage with pytest-cov (Pytest plugin for measuring coverage).
• How to automate tests using pytest with TravisCI.
• Automatic coverage reporting with Coveralls.

• introduction to CI with Travis: https://www.youtube.com/watch?v=buXwBr9H3VY
• introduction to pytest: https://www.youtube.com/watch?v=LdVJj65ikRY
• python doctest module: https://docs.python.org/2/library/doctest.html
• automated tests with pytest: https://ilovesymposia.com/2014/10/01/continuous-integration-0-automated-tests-with-pytest/
• measuring test coverage: https://ilovesymposia.com/2014/10/02/continuous-integration-1-test-coverage/
• setting up test configuration files: https://ilovesymposia.com/2014/10/13/continuous-integration-in-python-3-set-up-your-test-configuration-files/
• using Travis-CI to run your tests automatically with each git push: https://ilovesymposia.com/2014/10/15/continuous-integration-in-python-4-set-up-travis-ci/
• continuously check your test coverage using Coveralls (https://coveralls.io/): https://ilovesymposia.com/2014/10/15/continuous-integration-in-python-5-report-test-coverage-using-coveralls/
• badge your repo: https://ilovesymposia.com/2014/10/17/continuous-integration-in-python-6-show-off-your-work/

sudo pip install pytest pytest-cov coveralls  

Actually, coveralls installation is not required locally. It is used by Travis CI to push coverage report to the Coveralls service.

To test with Travis CI, you need a github account.
Github supports webhook with Travis CI.
Travis CI runs tests every time you push to your GitHub repository.

Travis pushes the coverage report to Coveralls every time Travis is run.
You can sign in to Travis and coveralls with your github account.

git clone https://github.com/ksator/continuous-integration.git  
cd continuous-integration/  

This is a testing tool for python.
By default, pytest discovers tests by looking at files that have these patterns test_*.py and *_test.py
Type py.test on the command line at your project root directory: Pytest will traverse all your subdirectories, gather up all the test files, run your tests, and provide an output.

pytest installation:

pip install pytest

maths.py has some function definitions. tests/test_multiple.py has the tests for math.py

The doctest module searches for pieces of text that look like interactive Python sessions and then executes those sessions to verify that they work exactly as shown.
https://docs.python.org/2/library/doctest.html
Pytest supports doctests with the --doctest-modules flag.

maths3.py is using doctests. The tests are in the code comment.

Testing is important, measuring coverage is also important.
Pytest can measure coverage for you with the coverage plugin, found in the pytest-cov package. pytest-cov is a Pytest plugin for measuring coverage.

pytest-cov installation:

pip install pytest-cov

Use the option --cov to mesure coverage.
With the option --cov-report term-missing, we can see which lines are not covered.

To make these tests and reports automatic, we use a github webhook with Travis CI.
Travis tests with py.test the repo every time you push to your GitHub repository.
The file .travis.yml has the Travis CI details.
The file requirements.txt has the list of python packages Travis installs.

Our .travis.yml file use the service Coveralls: Travis pushes the coverage report to Coveralls every time it runs, i.e., every time you push something to your GitHub repository.

py.test  
py.test -v  

py.test --cov .  
py.test --cov . -v  

py.test --cov maths.py  
py.test --cov maths.py -v  

py.test --cov-report term-missing --cov .  
py.test --cov-report term-missing --cov . -v  

py.test --cov-report term-missing --cov=maths.py  
py.test --cov-report term-missing --cov=maths.py -v  

py.test --doctest-modules -v  

py.test --doctest-modules --cov .  
py.test --doctest-modules --cov . -v  

py.test --doctest-modules --cov . --cov-report term-missing  
py.test --doctest-modules --cov . --cov-report term-missing -v  

py.test --doctest-modules --cov=maths3.py  
py.test --doctest-modules --cov=maths3.py -v   

py.test --doctest-modules --cov=maths3.py --cov-report term-missing  
py.test --doctest-modules --cov=maths3.py --cov-report term-missing -v  

You can use a setup.cfg file at the root of the project with configuration options (ignore maths2.py, cov-report term-missing, ....) to then invoke your tests with a simple call to py.test.
More details:
https://ilovesymposia.com/2014/10/13/continuous-integration-in-python-3-set-up-your-test-configuration-files/
http://pytest.org/latest/customize.html
http://coverage.readthedocs.io/en/latest/config.html

You can use the module py_compile to validate the syntax of a python script.

python -m py_compile maths.py