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ipython_pytest

This little IPython extension gives you the ability to run tests using Pytest in an IPython Notebook.

Note: There are now better and more actively maintained tools to achieve this. There was also a rejected Pytest feature request for supporting notebooks - see the discussion for interesting details about this challenge:

• jupyter-pytest-2
• ipytest
• pytest_exploratory
• Pytest issue #2268

See also testbook for adding separate unit tests for a notebook.

The motivation for the extension was to make it possible to demonstrate test-driven development using pytest in an IPython notebook driven presentation.

This extension does not attempt to enable using notebooks as test suites. The intention is also not to collect test results from multiple cells, but to do separate test runs for cells in an interactive presentation.

This extension attempts to achieve for pytest what the ipython_nose extension does for nose. Unfortunately it isn't able to inject globals from the notebook environment into the test like the %%nose cell magic in ipython_nose. Instead, in ipython_pytest, all imports, constants and helper functions need to be contained in the test cell itself.

Installation

• Make sure your IPython Notebook server can import ipython_pytest.py (e.g. copy it to a directory in your PYTHONPATH, or modify PYTHONPATH before starting IPython Notebook). It's also probably sufficient to have ipython_pytest.py in the directory from which you run the notebook, e.g.:

  $ ls
  ipython_pytest.py
  $ ipython notebook
  

• You can also install it in a virtualenv in development mode:

  $ cd ipython-pytest
  $ pip install -e .
  

Usage

• Add a cell containing:

  %load_ext ipython_pytest
  

  somewhere in your notebook.

• Write tests that conform to Pytest conventions, e.g.:

  def test_arithmetic():
      assert 1+1 == 2
  

• Add a cell consisting of:

  %%pytest
  
  def test_my_stuff():
      assert 42 == 42
  

  to your notebook and run that cell. That will discover your test_* functions, run them, and show console output from Pytest.

• Pass standard Pytest arguments to the magic:

  %%pytest --tb=short
  

Caveats

• None of the objects defined in other cells of the notebook are available in the test cell.

Authors

• Antti Kaihola <antti dot kaihola at wartsila dot com>

Acknowledgements

Thanks to Taavi Burns for the idea in his ipython_nose package.

Get the code

git clone https://github.com/akaihola/ipython_pytest.git

Copyright

Copyright (c) 2016, 2018, Antti Kaihola.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

Neither the name of the developers nor the names of contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.