gitlab-ci.yml: 'script: -pytest cannot find any tests to check' - pytest

Question

I'm having trouble implementing a toy example that runs pytest within .gitlab-ci.yml
gitlab_ci is a repo containing a single file test_hello.py
gitlab_ci/
test_hello.py
test_hello.py
# test_hello.py
import pytest
def hello():
print("hello")
def hello_test():
assert hello() == 'hello'
.gitlab-ci.yml
# .gitlab-ci.yml
pytest:
image: python:3.6
script:
- apt-get update -q -y
- pip install pytest
- pytest # if this is removed, the job outputs 'Success'
CI/CD terminal output
$ pytest
=== test session starts ===
platform linux -- Python 3.6.9, pytest-5.2.0, py-1.8.0, pluggy-0.13.0
rootdir: /builds/kunov/gitlab_ci
collected 0 items
=== no tests ran in 0.02s ===
ERROR: Job failed: exit code 1
I'm not sure why the test did not run... pytest does not seem to recognize test_hello.py
Solution
Put the python file inside the newly creared tests folder:
gitlab_ci/
.gitlab-ci.yml
tests/
test_hello.py
Modify gitlab-ci.yml in the following manner:
# .gitlab-ci.yml
pytest:
image: python:3.6
script:
- apt-get update -q -y
- pip install pytest
- pwd
- ls -l
- export PYTHONPATH="$PYTHONPATH:."
- python -c "import sys;print(sys.path)"
- pytest
And test_hello.py would stay the same as before.

Answer 1

This blog post mentions a similar pipeline, but:
However, this did not work as pytest was unable to find the ‘bild’ module (ie. the source code) to test.
The problem encountered here is that the ‘bild’ module is not able to be found by the test_*.py files, as the top-level directory of the project was not being specified in the system path:
pytest:
stage: Test
script:
- pwd
- ls -l
- export PYTHONPATH="$PYTHONPATH:."
- python -c "import sys;print(sys.path)"
- pytest
The OP kunov confirms in the comments:
It works now! I put the single file inside a newly created folder called 'test'

Answer 2

Manipulation of the PYTHONPATH variable is considered by some to be a bad practice (see e.g., this answer on stackoverflow or this Level Up Coding post). While this is possible not a huge issue in the scope of a GitLab CI job, here is a solution based on Alberto Mardegan's comment at the mentioned blog post without the need to fiddle with PYTHONPATH (also somewhat cleaner):
pytest:
stage: Test
script:
- pwd
- ls -l
- python -m pytest
Why does this work? From the pytest docs:
You can invoke testing through the Python interpreter from the command
line:
python -m pytest [...]
This is almost equivalent to invoking the
command line script pytest [...] directly, except that calling via
python will also add the current directory to sys.path.

Answer 3

test_hello.py
def test_hello():#func name must start with "test_",not "hello_test"