Add path filter for unit tests

[simonzhaoms]

Description

This PR adds a path filter to check if any changes to the unit tests code, thus the unit tests will not run if only docs are changed. The paths to trigger the unit tests include (Please confirm @miguelgfierro @pradnyeshjoshi):

• examples/
• recommenders/
• tests/
• setup.py

Related Issues

Checklist:

• I have followed the contribution guidelines and code style for this project.
• I have added tests covering my contributions.
• I have updated the documentation accordingly.
• This PR is being made to staging branch and not to main branch.

[miguelgfierro]

it seems there are some conflicts. Simon one question, how can we check that this is effective? do you need the code to be in staging or main? for example, if you change a markdown now, are the tests not triggered?

[simonzhaoms]

it seems there are some conflicts. Simon one question, how can we check that this is effective? do you need the code to be in staging or main? for example, if you change a markdown now, are the tests not triggered?

I forgot you just merged the PR. No wonder all unit tests are triggered.

[simonzhaoms]

@miguelgfierro I know what's going on. As said for the pull_request_target event, it will run in the context of the base of the pull request, rather than in the context of the merge commit, as the pull_request event does.
https://github.com/microsoft/recommenders/blob/e16c72ed9d0feb448c399b697dce7eb8cf1fd9c0/.github/workflows/azureml-unit-tests.yml#L8-L21

I think the path filter at the workflow level works:
https://github.com/microsoft/recommenders/blob/4a6754fd28f9b41556bdc882bd448fb4964d3c04/.github/workflows/azureml-unit-tests.yml#L22-L28

And the path filter action at the job level works as well:
https://github.com/microsoft/recommenders/blob/cd9946a4b2d2ee6ea8ffec24f7ab3d423e5e177e/.github/workflows/azureml-unit-tests.yml#L33-L60

[miguelgfierro]

@simonzhaoms have you tried this code? do you know if it is not triggered if there is a change in a readme?

[miguelgfierro]

ok, let's see if this works