Setting Up Python: Environment and Project Scaffolding

I’ve been writing Python bare on remote servers for a while and haven’t touched it on my Mac in ages. Recently I had a task that needed Python, so I took the opportunity to properly sort out the Python environment setup and project scaffolding issues I’ve encountered.

Example project: https://github.com/rainfd/python-example-project

ENVIRONMENT

Installing Python

brew install python

This installs both Python 2 and 3. Although Python 2 officially reached end-of-life this year, many systems still running in production default to Python 2. CentOS 7.6, for instance, only started defaulting to Python 3. So for the next few years, Python 2 is still unavoidable.

IDE

Python isn’t my primary language, so buying PyCharm doesn’t make much sense. Among the other common IDEs (VSCode, Sublime Text 3, Atom), I went with VSCode. Main reason: I also do Golang development in VSCode. Setting up Python-related config barely requires any tinkering.

Installing the Python Plugin

Search for the official Python plugin in the marketplace and install it directly.

pipenv

brew install pipenv

Compared to pyenv, I personally find pipenv easier to install and use, plus it has thorough documentation.

Creating a Virtual Environment

$ cd python-example-project
$ pipenv --three

$ pipenv shell
(python-example-project) $ pipenv install package

(python-example-project) $ pipenv --venv
/Users/rainfd/.local/share/virtualenvs/python-example-project-9IUo4aoR

Configuring the Virtual Environment in VSCode

Press ⇧⌘P/F1, type select interpreter, and choose the venv path listed above. Or add this to your workspace settings:

{
  "python.pythonPath": "/Users/rainfd/.local/share/virtualenvs/python-example-project-9IUo4aoR/bin/python"
}

Shebang

#!/usr/bin/env python
# -*- encoding: utf-8 -*-

Python files typically start with a shebang and author/comment notes. Use VSCode’s built-in Snippets for this. Go to Preferences > User Snippets, enter python.json, and add:

{
  "HEADER": {
    "prefix": "header",
    "body": ["#!/usr/bin/env python", "# -*- encoding: utf-8 -*-"]
  }
}

PROJECT

Unit Test

There are many unit test frameworks for Python, but the standard library ships with a solid one — unittest. No need to pull in extra dependencies.

Configuring unittest in VSCode

{
  "python.testing.unittestArgs": ["-v", "-s", ".", "-p", "*_test.py"],
  "python.testing.pytestEnabled": false,
  "python.testing.nosetestsEnabled": false,
  "python.testing.unittestEnabled": true
}

Mock

When using unittest, unittest.mock is indispensable. Compared to mock support in other languages, I find Python’s mock to be the easiest to use. Note: unittest.mock was added to the standard library in Python 3.3. If you’re using Python 2, you’ll need to install it separately: pipenv install mock

Log

For global logging, you can reference this gist: https://gist.github.com/kingspp/9451566a5555fb022215ca2b7b802f19 Configure each module’s log format and level via YAML.

In each module, just import the logger and you’re good to go:

logger = logging.getLogger(__name__)
logger.info("msg")