Update tox.ini with all linting commands under lint env

Added a new environement that runs all the linting commands at once.
Added a new environement that format source code according the the expected
linting format.

.github/CONTRIBUTING.md

@@ -26,6 +26,9 @@
 Run the test suite using your current python version, in offline mode.
 This will use the curently recorded HTTP requests + responses. It does not make any HTTP call, does not require an active internet connection.
 
+**Note:** the CI runs that command, if it fail you won't be able to merge
+your changes in GSpread.
+
 ```
 tox -e py
 ```
@@ -48,6 +51,24 @@ You can control vcrpy's [Record Mode](https://vcrpy.readthedocs.io/en/latest/usa
 GS_RECORD_MODE=all GS_CREDS_FILENAME=<YOUR_CREDS.json> tox -e py
 ```
 
+3. Format your code:
+
+Use the following command to format your code. Doing so will ensure
+all code respects the same format.
+
+```
+tox -e format
+```
+
+Then run the linter to validate change, if any.
+
+**Note:** the CI runs that command, if it fail you won't be able to merge
+your changes in GSpread.
+
+```
+tox -e lint
+```
+
 ## Render Documentation
 
 The documentation uses [reStructuredText](http://www.sphinx-doc.org/en/master/usage/restructuredtext/index.html#rst-index) markup and is rendered by [Sphinx](http://www.sphinx-doc.org/).

.github/workflows/lint_python.yml

@@ -11,14 +11,10 @@ jobs:
       - uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python }}
-      - run: pip install bandit black codespell flake8 isort mypy pytest pyupgrade safety tox
+      - run: pip install bandit mypy pyupgrade safety tox
       - run: bandit --recursive --skip B105,B110,B311,B605,B607 --exclude ./.tox .
         if: ${{ matrix.python >= '3.8' }}
-      - run: black --check .
-      - run: codespell  # --ignore-words-list="" --skip=""
-      - run: flake8 --ignore=E203 --max-complexity=10 --max-line-length=255
-                    --show-source --statistics .
-      - run: isort --check-only --profile black .
+      - run: tox -e lint
       - run: tox -e py
       - run: mypy --ignore-missing-imports . || true  # Need Python >= 3.6
       - run: shopt -s globstar && pyupgrade --py3-only **/*.py  # --py36-plus

lint-requirements.txt

@@ -0,0 +1,5 @@
+bandit==1.7.0
+black==21.7b0
+codespell==2.1.0
+flake8==3.9.2
+isort==5.9.3

tox.ini

@@ -2,7 +2,23 @@
 envlist = py36,py37,py38,py39
 skip_missing_interpreters = true
 
+# Used to run tests, **do not** set GS_CREDS_FILENAME to run off-line tests
 [testenv]
 passenv = GS_RECORD_MODE GS_CREDS_FILENAME
 deps = -r test-requirements.txt
 commands = pytest tests/
+
+# Used by the CI to check code format/security
+[testenv:lint]
+deps = -r lint-requirements.txt
+commands = black --check .
+        codespell --skip=".tox,.git" .
+        flake8 --ignore=E203 --max-complexity=10 --max-line-length=255 \
+            --show-source --statistics .
+        isort --check-only --profile black .
+
+# Used by developers to format code, best advised to be run before commit
+[testenv:format]
+deps = -r lint-requirements.txt
+commands = black .
+        isort --profile black .