Pytests Unit Testcase for Biking Endorphines

Introduction

So my first initial change for Parameterizing test-cases was a bit of failure - you can check this Parameterized Django Testcases At Biking Endorphines

Let's change that :)

Prerequisites - How to use Pytests

1. Install pytests with pip :

pip install pytest

2. Import Pytest in your file containing tests:

import pytest

3. But how do you actually use it ?

That's a good question.

First create a file with different name then pytest.py i.e. first_test.py and put similar content as I've created :

"""
Pytests example
"""
import pytest


def func(num):
    """
    Simple adding function for pytest showcase
    """
    return num + 1

def test_answer_fail():
    """
    Test for checking func with negative values
    """
    with pytest.raises(AssertionError):
        assert func(3) == 5

def test_answer_success():
    """
    Test for checking func with possitive values
    """
    assert func(4) == 5

Then use following bash command:

pytest -rs first_test.py

That should make following output:

pytest -rs first_pytest.py 
============================================================================================================ test session starts ============================================================================================================
platform linux2 -- Python 2.7.6, pytest-3.0.7, py-1.4.33, pluggy-0.4.0
rootdir: /home/bawi/projects/deployed/anselmos_blog/data/content/examples/pytest, inifile:
collected 2 items 

first_pytest.py ..

========================================================================================================= 2 passed in 0.02 seconds ==========================================================================================================

What changes I've made in code - a diff between code-commits using asciinema and vim-diff tool?

1. I've followed Good Integration Practices

What that means ? I've figure-out that this tests that I intent to create are out-side of django scope, so why not just put them literally out-side?

That's why I've created tests directory at directory bikingendorphines/tests and put all my test-files in there.

2. Test-Case itself.

Now I've change code so it looks like this :

"""
Tests for GPXReader class
"""

import pytest

from web.utils import GPXReader

@pytest.fixture(
    scope='module',
    params=[
        'bikingendorphines/example_data/15212277.gpx',
        'bikingendorphines/example_data/15212277.gpx'
    ]
)
def gpxreader(request):
    """
    Creates GPXReader instance with predefined gpx file
    """
    return GPXReader(request.param)

# pylint: disable=redefined-outer-name
def test_get_points(gpxreader):
    """
    Tests if there will be data output from get_points.

    Test if:
    - points exists for different types.
    - what will happen if types exists, but no data?
    """
    points = []
    for point in gpxreader.get_points():
        points.append(point)
    assert len(points) > 0

Final result

Check how much my code changed in this commit that shows all diffs:

Adds pytest. Adds GPXReader pytest-alike test

Code commits done for this post:

That's the same commit that changes GPXReader:

Adds pytest. Adds GPXReader pytest-alike test

And I've finally Squashed and Merged the gpx-solution as a initial solution.

Now I hope Travis will make my day better and confirm pylint&unittest as a good-to-go and create Pyreverse GH PAGE :)

Check results of Travis here

Update : Yes :) Travis accepted my changes and created pyreverse output in gh-pages, see GH_PAGE, Classes as PNG File

Tools and applications used:

LL (Lessons Learned)

1. Don't try to name your file with test-cases a pytest.py ! :)

If your filename will have name pytest.py as I did for my example of usage pytest, I've found python mismatched pytest and was confused.

Error like this popup:

________________________________________________________________________________________________________ ERROR collecting pytest.py _________________________________________________________________________________________________________
import file mismatch:
imported module 'pytest' has this __file__ attribute:
    /home/bawi/projects/deployed/anselmos_blog/data/content/examples/pytest/.env/local/lib/python2.7/site-packages/pytest.py
which is not the same as the test file we want to collect:
    /home/bawi/projects/deployed/anselmos_blog/data/content/examples/pytest/pytest.py
HINT: remove __pycache__ / .pyc files and/or use a unique basename for your test file modules

Solution:

You may overcome this issue change your name to something different than name of the library itself :)

2. Create plan and stick to it

That's more a Tips&Tricks then Lessons Learned, but it may also count as LL. I've figure-out finally how to manage the planning - I'll try my method and let you know if it will actually work:

  • Create a .md file for article
  • Make only main parts information of article that will briefly describe a kind-of-todo
  • Make all of this parts and describe them more deeply.

Acknowledgements

Accomplished:

1. Change behaviour of GPXReaderTestCase to more pytest alike and add some more test code

2. Push finally first version of GPX Reader to master via pull-request.

What's next

1. Add more tests to GPXReader test cases.

2. Add more business logic to GPXReader - endorphines-algorithms :)

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