Create Basic Python Environment (then start from red)

A basic Python envivonment setup using venv, pip, ruff, mypy, and pytest.

Start with creating a new venv folder

mkdir test
cd test/
python3 -m venv .venv
source .venv/bin/activate

The begining of the prompt line shows () to indicate the venv is active.

(.venv) ⚙leo@g16:~/Projects/test$

Notice that this perenthesis with inside does not gurantee the venv is working as ecpected. For example, if venv is not actually activated, the command line python3 foo.py can accidentally run the system wide python3 (/usr/bin/python3 foo.py), which is not desirable. Use which <COMMAND> to ensure .venv/bin/<COMMAND> is activated.

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Upgrade pip. Verify the venv is activated.

If there is a requirement.txt

pip install -r requirements.txt

(Else)

pip install --upgrade pip
which pip && which python3
# /home/leo/Projects/test/.venv/bin/pip
# /home/leo/Projects/test/.venv/bin/python3

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Install ruff, mypy, and pytest

which pip && which python3 # make sure venv is activated

Only if venv activation is verified:

pip install ruff
pip install mypy
pip install pytest

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Start coding by testing

Start by test.py then .py (red-green/TDD)

(.venv) ⚙leo@g16:~/Projects/test$ vim test_one.py
(.venv) ⚙leo@g16:~/Projects/test$ mypy test_one.py
Success: no issues found in 1 source file
(.venv) ⚙leo@g16:~/Projects/test$ pytest -q
.                                                                       [100%]
1 passed in 0.00s

(.venv) ⚙leo@g16:~/Projects/test$ vim main.py
(.venv) ⚙leo@g16:~/Projects/test$ mypy .
Success: no issues found in 2 source files

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Freeze requirements.txt

pip freeze > requirements.txt

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