DevOps Fundamentals: 08 - Creating and Executing Unit Tests: Instructions doesn't match code

[Daniel_B]

Instructions: 

To execute pytest within Databricks complete the following:

• sys.dont_write_bytecode = True - By default, Python generates .pyc bytecode files in a pycache directory. Setting it to True prevents this, which is useful in read-only environments.

Code in cell directly underneath:

• sys.dont_write_bytecode = False

Thanks. I hereby claim my $1000000 bug bounty. You're welcome.

[SumeshKashyap]

Good catch - the instruction text is right and the code cell is the typo. It should be sys.dont_write_bytecode = True. With False (Python's default) the tests still run, since Python silently ignores a failed .pyc write, but on a writable Git folder you end up with __pycache__ folders next to your test files.

Use the same pattern as the Databricks unit-testing docs:

import pytest, sys

sys.dont_write_bytecode = True  # skip .pyc files on a read-only filesystem

retcode = pytest.main([".", "-v", "-p", "no:cacheprovider"])  # no .pytest_cache either

assert retcode == 0, "The pytest invocation failed. See the log for details."

-p no:cacheprovider is the companion setting - it stops pytest writing its .pytest_cache folder for the same reason.

If you already ran the lab with False and see __pycache__ folders in your repo, delete them (or add __pycache__/ to .gitignore) so they don't get committed.

To get the notebook fixed for other learners, report it to the Academy team: https://help.databricks.com/s/contact-us?ReqType=training

Docs: https://docs.databricks.com/aws/en/notebooks/testing