Pytest - second example beyond hello world

Archive - Originally posted on "The Horse's Mouth" - 2016-01-08 07:03:16 - Graham Ellis
Moving on from my hello Pytest World example, lets add some more tests and put the code we're testing into a separate file. The test code is [here] and - if working in a TDD (Test Driven Developent) mode it will be written first - forming the specificiation for the class you're writing.

I have brought the code to be tested in with:

from mathstuff import *

Having carefully thought through whether "from" to bring the code into my current namespace or "import" to keep it separate, I've decided (in order to keep the training examples a bit shorter to use import. For a small real-world setup this might be a good decision, for a large and complex setup with lots of classes to be tested, from would be best. The file mathstuff.py is [here]

In addition to the "hello world" example, I've added ...

1. Further tests ... identified by being methods with names starting test_

2. A test which starts with the name another_; in order for this to be picked up by the park of pytest that seeks out the tests, I've provided a configuration file, setup.cfg which may be found [here], as follows:

  [pytest]

  python_functions = another_* test_*

3. I have decorated one of the tests to indicate that I know it will fail

  @pytest.mark.xfail

  def test_add_003():

    assert addition(10,15) == 26

4. I have provided a setup routine to be run before each and every test (but better ways of doing this are shown in later examples):

  def setup_function(summat):

    print("The world is round {}".format(summat))

5. I have run my tests with the -s option so that any print statements within are run / displayed (default is that stdout is supressed)

python -m pytest -s test_mathfuncs.py

Full code including sample output from a run ... [here]

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Pytest - second example beyond hello world