[issue-532] Add linter action

.flake8

@@ -0,0 +1,4 @@
+[flake8]
+max-line-length = 119
+exclude = src/spdx/parser/tagvalue/parsetab.py
+extend-ignore = E203

.github/workflows/check_codestyle.yml

@@ -0,0 +1,33 @@
+name: Run Linter
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  check_code_style:
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: bash
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, macos-latest, windows-latest ]
+        python-version: [ "3.7", "3.8", "3.9", "3.10", "3.11" ]
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Installation
+        run: pip install ".[codestyle]"
+      - name: Check code with isort
+        run: |
+          isort src tests --check
+          black src tests --check
+          flake8 src tests

.github/workflows/install_and_test.yml

@@ -3,7 +3,7 @@ name: Install and Test
 on:
   push:
     branches:
-      - refactor-python-tools
+      - main
   pull_request:
   workflow_dispatch:
 

CONTRIBUTING.md

@@ -47,23 +47,36 @@ Here's the process to make changes to the codebase:
    of [the Developer Certificate of Origin](https://developercertificate.org/). Git has utilities for signing off on
    commits: `git commit -s` or `--signoff` signs a current commit, and `git rebase --signoff <revision-range>`
    retroactively signs a range of past commits.
-
 6. Test your changes:
    ```sh
-   python setup.py test # in the repo root
+   pip install pytest
+   pytest -vvs # in the repo root
    ```
-   You may use other test runners, such as `pytest` or `nose` at your preference.
-7. Push the branch to your fork on GitHub:
+
+7. Check your code style. When opening a pull request, your changes will automatically be checked with `isort`, `black` 
+   and `flake8` to make sure your changes fit with the rest of the code style. 
+    ```sh
+   pip install .[code_style]
+   # run the following commands in the repo root
+   isort src tests 
+   black src tests
+   flake8 src tests 
+   ```
+   `black` and `isort` will automatically format the code and sort the imports. The configuration for these linters 
+   can be found in the `pyproject.toml`. `flake8` lists all problems found which then need to be resolved manually.
+   The configuration for the linter can be found in the `.flake8` file.
+
+8. Push the branch to your fork on GitHub:
    ```sh
    git push origin fix-or-improve-something
    ```
-8. Make a pull request on GitHub.
-9. Continue making more changes and commits on the branch, with `git commit --signoff` and `git push`.
-10. When done, write a comment on the PR asking for a code review.
-11. Some other developer will review your changes and accept your PR. The merge should be done with `rebase`, if
+9. Make a pull request on GitHub.
+10. Continue making more changes and commits on the branch, with `git commit --signoff` and `git push`.
+11. When done, write a comment on the PR asking for a code review.
+12. Some other developer will review your changes and accept your PR. The merge should be done with `rebase`, if
     possible, or with `squash`.
-12. The temporary branch on GitHub should be deleted (there is a button for deleting it).
-13. Delete the local branch as well:
+13. The temporary branch on GitHub should be deleted (there is a button for deleting it).
+14. Delete the local branch as well:
     ```sh
     git checkout master
     git pull -p

pyproject.toml

@@ -29,6 +29,7 @@ dynamic = ["version"]
 
 [project.optional-dependencies]
 test = ["pytest"]
+code_style = ["isort", "black", "flake8"]
 
 [project.scripts]
 pyspdxtools = "spdx.clitools.pyspdxtools:main"
@@ -50,3 +51,11 @@ git_describe_command = ["git", "describe", "--dirty", "--tags", "--long", "--mat
 
 [tool.aliases]
 release = "clean --all sdist --formats=gztar bdist_wheel"
+
+[tool.black]
+line-length = 119
+include = "(^/src/.*.py|^/tests/.*.py)"
+
+[tool.isort]
+profile = "black"
+line_length = 119