add basic contribution guideline, see brainelectronics#67

Author: brainelectronics

docs/CONTRIBUTING.md

@@ -4,4 +4,208 @@ Guideline to contribute to this package
 
 ---------------
 
-## TBD
+## General
+
+You're always welcome to contribute to this package with or without raising an
+issue before creating a PR.
+
+Please follow this guideline covering all necessary steps and hints to ensure
+a smooth review and contribution process.
+
+## Code
+
+To test and verify your changes it is recommended to run all checks locally in
+a virtual environment. Use the following commands to setup and install all
+tools.
+
+```bash
+python3 -m venv .venv
+source .venv/bin/activate
+
+pip install -r requirements-test.txt
+```
+
+For very old systems it might be necessary to use an older version of
+`pre-commit`, an "always" working version is `1.18.3` with the drawback of not
+having `flake8` and maybe other checks in place.
+
+### Format
+
+The Python code format is checked by `flake8` with the default line length
+limit of 79. Further configuration can be found in the `.flake8` file in the
+repo root.
+
+The YAML code format is checked by `yamllint` with some small adjustments as
+defined in the `.yamllint` file in the repo root.
+
+Use the following commands (inside the virtual environment) to run the Python
+and YAML checks
+
+```bash
+# check Python
+flake8 .
+
+# check YAML
+yamllint .
+```
+
+### Tests
+
+Every code should be covered by a unittest. This can be achieved for
+MicroPython up to some degree, as hardware specific stuff can't be always
+tested by a unittest.
+
+For now `mpy_unittest` is used as tool of choice and runs directly on the
+divice. For ease of use a Docker container is used as not always a device is
+at hand or connected to the CI.
+
+The hardware UART connection is faked by a TCP connection providing the same
+interface and basic functions as a real hardware interface.
+
+The tests are defined, as usual, in the `tests` folder. The `mpy_unittest`
+takes and runs all tests defined and imported there by the `__init__.py` file.
+
+Further tests, which could be called Integration tests, are defined in this
+folder as well. To be usable they may require a counterpart e.g. a client
+communicating with a host, which is simply achieved by two Docker containers,
+defined in the `docker-compose-tcp-test.yaml` or `docker-compose-rtu-test.yaml`
+file, located in the repo root. The examples for TCP or RTU client usage are
+used to provide a static setup.
+
+Incontrast to Python, no individual test results will be reported as parsable
+XML or similar, the container will exit with either `1` in case of an error or
+with `0` on success.
+
+```bash
+# build and run the "native" unittests
+docker build --tag micropython-test --file Dockerfile.tests .
+
+# Execute client/host TCP examples
+docker compose up --build --exit-code-from micropython-host
+
+# Run client/host TCP tests
+docker compose -f docker-compose-tcp-test.yaml up --build --exit-code-from micropython-host
+
+# Run client/host RTU examples with faked RTU via TCP
+docker compose -f docker-compose-rtu.yaml up --build --exit-code-from micropython-host
+
+# Run client/host RTU tests
+docker compose -f docker-compose-rtu-test.yaml up --build --exit-code-from micropython-host
+```
+
+### Precommit hooks
+
+This repo is equipped with a `.pre-commit-config.yaml` file to combine most of
+the previously mentioned checks plus the changelog validation, see next
+section, into one handy command. It additionally allows to automatically run
+the checks on every commit.
+
+In order to run this repo's pre commit hooks, perform the following steps
+
+```bash
+# install pre-commit to run before each commit, optionally
+pre-commit install
+
+pre-commit run --all-files
+```
+
+## Changelog
+
+The changelog format is based on [Keep a Changelog][ref-keep-a-changelog], and
+this project adheres to [Semantic Versioning][ref-semantic-versioning].
+
+Please add a changelog entry for every PR you contribute. The versions are
+seperated into `MAJOR.MINOR.PATCH`:
+
+- Increment the major version by 1 in case you created a breaking, non
+backwards compatible change which requires the user to perform additional
+tasks, adopt his currently running code or in general can't be used as is anymore.
+- Increment the minor version by 1 on new "features" which can be used or are
+optional, but in either case do not require any changes by the user to keep
+the system running after upgrading.
+- Increment the patch version by 1 on bugfixes which fix an issue but can be
+used out of the box, like features, without any changes by the user. In some
+cases bugfixes can be breaking changes of course.
+
+Please add the date the change has been made as well to the changelog
+following the format `## [MAJOR.MINOR.PATCH] - YYYY-MM-DD`. It is not
+necessary to keep this date up to date, it is just used as meta data.
+
+The changelog entry shall be short but meaningful and can of course contain
+links and references to other issues or PRs. New lines are only allowed for a
+new bulletpoint entry. Usage examples or other code snippets should be placed
+in the code documentation, README or the docs folder.
+
+### General
+
+The package version file, located at `umodbus/version.py` contains the latest
+changelog version.
+
+To avoid a manual sync of the changelog version and the package version file
+content, the `changelog2version` package is used. It parses the changelog,
+extracts the latest version and updates the version file.
+
+The package version file can be generated with the following command consuming
+the latest changelog entry
+
+```bash
+changelog2version \
+	--changelog_file changelog.md \
+	--version_file umodbus/version.py \
+	--version_file_type py \
+	--debug
+```
+
+To validate the existing package version file against the latest changelog
+entry use this command
+
+```bash
+changelog2version \
+	--changelog_file=changelog.md \
+	--version_file=umodbus/version.py \
+	--validate
+```
+
+### MicroPython
+
+On MicroPython the `mip` package is used to install packages instead of `pip`
+at MicroPython version 1.20.0 and newer. This utilizes a `package.json` file
+in the repo root to define all files and dependencies of a package to be
+downloaded by [`mip`][ref-mip-docs].
+
+To avoid a manual sync of the changelog version and the MicroPython package
+file content, the `setup2upypackage` package is used. It parses the changelog,
+extracts the latest version and updates the package file version entry. It
+additionally parses the `setup.py` file and adds entries for all files
+contained in the package to the `urls` section and all other external
+dependencies to the `deps` section.
+
+The MicroPython package file can be generated with the following command based
+on the latest changelog entry and `setup` file.
+
+```bash
+upy-package \
+	--setup_file setup.py \
+	--package_changelog_file changelog.md \
+	--package_file package.json
+```
+
+To validate the existing package file against the latest changelog entry and
+setup file content use this command
+
+```bash
+upy-package \
+	--setup_file setup.py \
+	--package_changelog_file changelog.md \
+	--package_file package.json \
+	--validate
+```
+
+## Documentation
+
+Please check the `docs/DOCUMENTATION.md` file for further details.
+
+<!-- Links -->
+[ref-keep-a-changelog]: https://keepachangelog.com/en/1.0.0/
+[ref-semantic-versioning]: https://semver.org/spec/v2.0.0.html
+[ref-mip-docs]: https://docs.micropython.org/en/v1.20.0/reference/packages.html