Prepare the Python hands-on environment

Lab briefing

Two editing surfaces connect to the same environment module while another module remains separate.

Original concept illustration (SVG)

Make the editor and terminal use the same environment.

At a glance	Your route
Level and time	100; 20 minutes (facilitation estimate)
Starting action	Locate the library import root before choosing a test framework.
Learner materials	Download 02-python.zip
Workspace	Open the extracted kit root; run the baseline from `library` relative to that root
Expected initial check	The existing unittest tests are discovered and pass.
Setup help	Download, extract, local Git and optional GitHub

[!NOTE] A test that cannot import the application has not tested its behavior.

Concepts · First task · Evidence checklist · Reset

Learning objectives

Select the same interpreter in VS Code and the terminal.
Understand the fixture’s import root and test runner.
Keep virtual environments and caches on the selected work drive.

Before you start

Read environment setup. Use a supported Python interpreter and VS Code’s Python extension. The supplied library tests use unittest.TestCase; pytest can execute them in the pytest lab. Do not install packages for the standard- library baseline unless a command actually requires them.

Concepts and use cases

Item	Purpose
Interpreter	Runs the code; its selection determines available packages
Virtual environment	Keeps this fixture’s dependencies separate
Working directory	Determines top-level imports and relative files
Test discovery	Finds cases; it is distinct from running them

Exercise scenario

The library lives under AccelerateDevGHCopilot/library. Its imports expect application_core, console, and infrastructure below the current import root.

Task 1 - Prepare the isolated copy

node scripts/prepare-hands-on.js --lab 02-python --destination /Volumes/T9/Dev/oss/workshop-runs/02-python

Open the printed copy alone, select the Python interpreter, then change into library in its terminal. Record the interpreter and working directory.

Task 2 - Discover and run the existing tests

python -m unittest discover -s tests -p "test_*.py" -v

Confirm actual test names appear.
Record assertion results and the exit status.
In the editor, use Python: Configure Tests and select unittest with tests as the directory for this baseline.
If the later pytest lab is selected, create .venv in the disposable copy, install its declared pytest requirement there, and select that interpreter.
Avoid automatic discovery across the entire curriculum; it contains independent copies with different import roots.

Verify your work

Terminal and editor use the intended interpreter.
Tests are discovered from library, not an unrelated directory.
No zero-test result is called a passing baseline.
No package, environment or cache was created on the OS disk for this workshop.

Troubleshooting

ModuleNotFoundError: application_core usually indicates the wrong working/import root. Do not scatter sys.path changes across tests. A missing pytest package in a unittest baseline is not a reason to install pytest globally.

Independent practice

Compare unittest discovery with pytest collection on the same TestCase classes. Explain why selecting both frameworks in VS Code does not mean both ran.

Reset

Close the copied workspace and restore only preferences changed for it. Keep shared interpreters and other projects’ virtual environments intact.