Why PyTest is not collecting tests (collected 0 items)?

Question

I have been trying to run unit tests using pytest.

I wrote a module with one class and some methods inside that class, and I wrote a unit test for this module (with a simple assert statement to check equality of lists) where I first instantiated the class with a list.

Then I invoke a method on that object (from the class). Both test.py and the script to be tested are in the same folder. When I run pytest on it, it reports "collected 0 items".

I am new to pytest and but I am unable to run their examples successfully. What am I missing here?

I am running Python version 3.5.1 and pytest version 2.8.1 on Windows 7.

My test.py code:

from sort_algos import Sorts

def integer_sort_test():
    myobject1 = Sorts([-100, 10, -10])
    assert myobject1.merge_sort() == [-101, -100, 10]

sort_algos.py is a module containing Sorts class.

merge_sort is a method from Sorts.

Please post a [mcve]. What would you expect as a result if you place an empty `.py` file? — Zulan, May 20 '16 at 19:50
Random memory - something about `.py` being skipped if it's executable - see if it is and either change it to non-executable, or see if `pytest` has a `include executable` option? — dwanderson, May 20 '16 at 20:15

score 163 · Accepted Answer · edited Mar 17 '20 at 06:37

163

pytest gathers tests according to a naming convention. By default any file that is to contain tests must be named starting with test_, classes that hold tests must be named starting with Test, and any function in a file that should be treated as a test must also start with test_.

If you rename your test file to test_sorts.py and rename the example function you provide above as test_integer_sort, then you will find it is automatically collected and executed.

This test collecting behavior can be changed to suit your desires. Changing it will require learning about configuration in pytest.

edited Mar 17 '20 at 06:37

alexei

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answered May 21 '16 at 19:12

cewing

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thanks a lot !Yes, that worked. OMG, I never realized that ! – Ramkumar Hariharan May 21 '16 at 19:45
Glad I was able to help. Would you mind marking this as the correct answer? Thanks! – cewing May 26 '16 at 04:55
Both links in this answer are now Error 404 :( – gerrit Jul 24 '19 at 13:41
Was stuck even KNOWING the naming convention but was ignoring it. Great reminder. Thanks – Robert Alexander Jan 31 '23 at 19:17

score 17 · Answer 2 · edited Nov 29 '20 at 06:08

I had the same issue, but my function was called test.py. I never thought that the issue would be the file name.

In the documentation it says:

pytest will run all files of the form test_*.py or *_test.py in the current directory and its subdirectories. More generally, it follows standard test discovery rules.

Exactly! The name should be test_.py or test_something.py and works for me.

I feel so stupid, hehe.

score 6 · Answer 3 · edited Feb 03 '22 at 05:42

I can't upvote yet but want to chime in with a combo solution that worked for me.

First, per above, I renamed my file with 'test_': test_hello.py.

Second, also per above, I renamed each bit I wanted to test with 'test_'

def test_greeting():
    print('Hello, world!')

def test_checkout():
    print("This is checkout")

def logout():
    print("This is logout")

def test_executable():
    """says hello world by default"""
    out = getoutput({prg})

And finally, to actually run the test, I entered the following on the command line:

python -m pytest -v test_hello.py

Without the -m there is a message the file cannot be opened. It works without the -v, but with it, it breaks down each part being tested. RESULT:

---------------------------------------------
collected 3 items

test_hello.py::test_greeting PASSED                                                                              [ 33%]
test_hello.py::test_checkout PASSED                                                                              [ 66%]
test_hello.py::test_executable FAILED


def test_executable():
        """says hello world by default"""
>       out = getoutput({prg})
E       NameError: name 'getoutput' is not defined

test_hello.py:12: NameError

As you can see, it skipped logout(), the part of the program with no test_, and delivered a useful error message. So, with that simple example, things are running as they should. Thank you to everyone who helped me put it together.

score 3 · Answer 4 · answered Jan 25 '21 at 04:15

I faced this issue too and it took me a whole day to find out that the class name should start with "Test" my class name was "test" instead. That made me run my code successfully.

Make sure your python test file name and method name should also start with "test_"

score 2 · Answer 5 · edited Jan 10 '22 at 21:50

This helped me a lot. Initially I named my tests below:

def login():
    print("This is login")

def checkout():
    print("This is checkout")

def logout():
    print("This is logout")

My pytest command ran without errors. However, no results were produced. I also observed:

collected 0 items

Hence I renamed the above tests to test_login(), test_checkout(), test_logout() and now I got successful results!

score 0 · Answer 6 · edited Nov 29 '20 at 06:16

I ran into this problem as well. And it was not caused by script names, but due to a plugin called "pytest-appium" which I have no intention to use in the first place.

I finally found it out from report: ('c:\python39\lib\site-packages\pytest_appium\plugin.py', 8, 'Skipped: no variables file')

Since plugin.py requires variables which I have no idea what it is for.

@pytest.fixture(scope='session')
def appium(variables):
    if not variables:
        pytest.skip('no variables file')

Solution:

pip uninstall pytest-appium

Julian Pavlov · Answer 7 · 2023-01-19T11:16:25.393

0

If you're still getting

collected 0 items

======================= no tests ran in X.XXs======================

save your files again (in VSCode) to get files updated

edited Jan 19 '23 at 11:16

answered Jan 19 '23 at 11:15

Julian Pavlov

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Why PyTest is not collecting tests (collected 0 items)?

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