CI: added flake8 github action (#364)

* CI: added flake8 github action
Handles #352

* minor: change path for flake8 action

* minor: fix spaces in ignore of flake8 action

* minor: add more ignore in flake8 action

* minor: try to add per-file-ignore to flake8 action

* minor: added flake8 to setup.cfg and makefile

.github/workflows/flake8.yaml

@@ -0,0 +1,24 @@
+# This workflow runs Flake8 on the PR
+# For more information see: https://github.com/marketplace/actions/python-flake8-lint
+name: PyLops-flake8
+
+on: [push, pull_request]
+
+jobs:
+  flake8-lint:
+    runs-on: ubuntu-latest
+    name: Lint
+    steps:
+      - name: Check out source repository
+        uses: actions/checkout@v2
+      - name: Set up Python environment
+        uses: actions/setup-python@v2
+        with:
+          python-version: "3.8"
+      - name: flake8 Lint
+        uses: py-actions/flake8@v2
+        with:
+          ignore: "E203,E501,W503,E402"
+          max-line-length: "88"
+          path: "pylops"
+          args: "--per-file-ignores=__init__.py:F401,F403,F405"

Makefile

@@ -39,3 +39,6 @@ doc:
 
 docupdate:
 	cd docs && make html && cd ..
+
+lint:
+	flake8 docs/ examples/ pylops/ pytests/ tutorials/

docs/source/contributing.rst

@@ -91,17 +91,26 @@ that the both old and new tests pass successfully:
 
    >>  make tests
 
-7. Commit your changes and push your branch to GitLab:
+7. Run flake8 to check the quality of your code:
 
 .. code-block:: bash
 
-   >>  git add .
+   >> make lint
+
+Note that at this point we are not enforcing flake8, rather this is used as a guideline and will also be run as
+part of our CI. Make sure to limit to a minimum flake8 warnings before making a PR.
+
+8. Commit your changes and push your branch to GitHub:
+
+.. code-block:: bash
+
+   >> git add .
    >> git commit -m "Your detailed description of your changes."
    >> git push origin name-of-your-branch
 
 Remember to add ``-u`` when pushing the branch for the first time.
 
-8. Submit a pull request through the GitHub website.
+9. Submit a pull request through the GitHub website.
 
 
 Pull Request Guidelines

environment-dev.yml

@@ -31,3 +31,4 @@ dependencies:
     - sphinx-gallery
     - nbsphinx
     - image
+    - flake8

requirements-dev.txt

@@ -22,3 +22,4 @@ pre-commit
 autopep8
 isort
 black
+flake8

setup.cfg

@@ -4,3 +4,9 @@ test=pytest
 [tool:pytest]
 addopts = --verbose
 python_files = pytests/*.py
+
+[flake8]
+ignore = E203, E501, W503, E402
+per-file-ignores =
+    __init__.py: F401, F403, F405
+max-line-length = 88