Local checking: pre commit

Checkers/linters/formatters & pre-commit

To make sure our code is PEP 8 compliant, we use:

• black code formatter
• Flake8 code linter
• mypy static type checker

There's a pre-commit config file (.pre-commit-config.yaml) in each repo. To utilize pre-commit, install pre-commit (, ) with pip3 install pre-commit and then either:

• pre-commit install - to install pre-commit into your git hooks. pre-commit will from now on run all the checkers/linters/formatters on every commit. If you later want to commit without running it, just run git commit with -n/--no-verify.
• Or if you want to manually run all the checkers/linters/formatters, run pre-commit run --all-files.

$ pre-commit run --all-files
[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
Trim Trailing Whitespace.................................................Failed
hookid: trailing-whitespace

Files were modified by this hook. Additional output:

Fixing release-conf.yaml
Fixing CONTRIBUTING.md

$ pre-commit run --all-files
Trim Trailing Whitespace.................................................Passed

• example .pre-commit-config.yaml:

repos:
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v2.2.3
    hooks:
    - id: check-added-large-files
    - id: check-ast
    - id: check-merge-conflict
    - id: check-yaml
    - id: detect-private-key
    - id: end-of-file-fixer
    - id: trailing-whitespace
    - id: flake8
      args: [--max-line-length=100]
-   repo: https://github.com/ambv/black
    rev: stable
    hooks:
    - id: black
      language_version: python3.6
-   repo: https://github.com/pre-commit/mirrors-mypy
    rev: v0.711
    hooks:
    -   id: mypy
        args: [--no-strict-optional, --ignore-missing-imports]