Reorganize CONTRIBUTING.md documentation. (#9281)

1 files changed, 189 insertions, 82 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 1d7bb8f969..b6a70f7ffe 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,4 +1,31 @@
-# Contributing code to Synapse
+Welcome to Synapse
+
+This document aims to get you started with contributing to this repo! 
+
+- [1. Who can contribute to Synapse?](#1-who-can-contribute-to-synapse)
+- [2. What do I need?](#2-what-do-i-need)
+- [3. Get the source.](#3-get-the-source)
+- [4. Install the dependencies](#4-install-the-dependencies)
+  * [Under Unix (macOS, Linux, BSD, ...)](#under-unix-macos-linux-bsd-)
+  * [Under Windows](#under-windows)
+- [5. Get in touch.](#5-get-in-touch)
+- [6. Pick an issue.](#6-pick-an-issue)
+- [7. Turn coffee and documentation into code and documentation!](#7-turn-coffee-and-documentation-into-code-and-documentation)
+- [8. Test, test, test!](#8-test-test-test)
+  * [Run the linters.](#run-the-linters)
+  * [Run the unit tests.](#run-the-unit-tests)
+  * [Run the integration tests.](#run-the-integration-tests)
+- [9. Submit your patch.](#9-submit-your-patch)
+  * [Changelog](#changelog)
+    + [How do I know what to call the changelog file before I create the PR?](#how-do-i-know-what-to-call-the-changelog-file-before-i-create-the-pr)
+    + [Debian changelog](#debian-changelog)
+  * [Sign off](#sign-off)
+- [10. Turn feedback into better code.](#10-turn-feedback-into-better-code)
+- [11. Find a new issue.](#11-find-a-new-issue)
+- [Notes for maintainers on merging PRs etc](#notes-for-maintainers-on-merging-prs-etc)
+- [Conclusion](#conclusion)
+
+# 1. Who can contribute to Synapse?
 
 Everyone is welcome to contribute code to [matrix.org
 projects](https://github.com/matrix-org), provided that they are willing to
@@ -9,70 +36,179 @@ license the code under the same terms as the project's overall 'outbound'
 license - in our case, this is almost always Apache Software License v2 (see
 [LICENSE](LICENSE)).
 
-## How to contribute
+# 2. What do I need?
+
+The code of Synapse is written in Python 3. To do pretty much anything, you'll need [a recent version of Python 3](https://wiki.python.org/moin/BeginnersGuide/Download).
+
+The source code of Synapse is hosted on GitHub. You will also need [a recent version of git](https://github.com/git-guides/install-git).
+
+For some tests, you will need [a recent version of Docker](https://docs.docker.com/get-docker/).
+
+
+# 3. Get the source.
 
 The preferred and easiest way to contribute changes is to fork the relevant
-project on github, and then [create a pull request](
+project on GitHub, and then [create a pull request](
 https://help.github.com/articles/using-pull-requests/) to ask us to pull your
 changes into our repo.
 
-Some other points to follow:
+Please base your changes on the `develop` branch.
+
+```sh
+git clone git@github.com:YOUR_GITHUB_USER_NAME/synapse.git
+git checkout develop
+```
+
+If you need help getting started with git, this is beyond the scope of the document, but you
+can find many good git tutorials on the web.
+
+# 4. Install the dependencies
 
- * Please base your changes on the `develop` branch.
+## Under Unix (macOS, Linux, BSD, ...)
 
- * Please follow the [code style requirements](#code-style).
+Once you have installed Python 3 and added the source, please open a terminal and
+setup a *virtualenv*, as follows:
+
+```sh
+cd path/where/you/have/cloned/the/repository
+python3 -m venv ./env
+source ./env/bin/activate
+pip install -e ".[all,lint,mypy,test]"
+pip install tox
+```
+
+This will install the developer dependencies for the project.
+
+## Under Windows
+
+TBD
 
- * Please include a [changelog entry](#changelog) with each PR.
 
- * Please [sign off](#sign-off) your contribution.
+# 5. Get in touch.
 
- * Please keep an eye on the pull request for feedback from the [continuous
-   integration system](#continuous-integration-and-testing) and try to fix any
-   errors that come up.
+Join our developer community on Matrix: #synapse-dev:matrix.org !
 
- * If you need to [update your PR](#updating-your-pull-request), just add new
-   commits to your branch rather than rebasing.
 
-## Code style
+# 6. Pick an issue.
+
+Fix your favorite problem or perhaps find a [Good First Issue](https://github.com/matrix-org/synapse/issues?q=is%3Aopen+is%3Aissue+label%3A%22Good+First+Issue%22)
+to work on.
+
+
+# 7. Turn coffee and documentation into code and documentation!
 
 Synapse's code style is documented [here](docs/code_style.md). Please follow
 it, including the conventions for the [sample configuration
 file](docs/code_style.md#configuration-file-format).
 
-Many of the conventions are enforced by scripts which are run as part of the
-[continuous integration system](#continuous-integration-and-testing). To help
-check if you have followed the code style, you can run `scripts-dev/lint.sh`
-locally. You'll need python 3.6 or later, and to install a number of tools:
+There is a growing amount of documentation located in the [docs](docs)
+directory. This documentation is intended primarily for sysadmins running their
+own Synapse instance, as well as developers interacting externally with
+Synapse. [docs/dev](docs/dev) exists primarily to house documentation for
+Synapse developers. [docs/admin_api](docs/admin_api) houses documentation
+regarding Synapse's Admin API, which is used mostly by sysadmins and external
+service developers.
 
-```
-# Install the dependencies
-pip install -e ".[lint,mypy]"
+If you add new files added to either of these folders, please use [GitHub-Flavoured
+Markdown](https://guides.github.com/features/mastering-markdown/).
+
+Some documentation also exists in [Synapse's GitHub
+Wiki](https://github.com/matrix-org/synapse/wiki), although this is primarily
+contributed to by community authors.
+
+
+# 8. Test, test, test!
+<a name="test-test-test"></a>
+
+While you're developing and before submitting a patch, you'll
+want to test your code.
+
+## Run the linters.
+
+The linters look at your code and do two things:
+
+- ensure that your code follows the coding style adopted by the project;
+- catch a number of errors in your code.
+
+They're pretty fast, don't hesitate!
 
-# Run the linter script
+```sh
+source ./env/bin/activate
 ./scripts-dev/lint.sh
 ```
 
-**Note that the script does not just test/check, but also reformats code, so you
-may wish to ensure any new code is committed first**.
+Note that this script *will modify your files* to fix styling errors.
+Make sure that you have saved all your files.
 
-By default, this script checks all files and can take some time; if you alter
-only certain files, you might wish to specify paths as arguments to reduce the
-run-time:
+If you wish to restrict the linters to only the files changed since the last commit
+(much faster!), you can instead run:
 
+```sh
+source ./env/bin/activate
+./scripts-dev/lint.sh -d
 ```
+
+Or if you know exactly which files you wish to lint, you can instead run:
+
+```sh
+source ./env/bin/activate
 ./scripts-dev/lint.sh path/to/file1.py path/to/file2.py path/to/folder
 ```
 
-You can also provide the `-d` option, which will lint the files that have been
-changed since the last git commit. This will often be significantly faster than
-linting the whole codebase.
+## Run the unit tests.
+
+The unit tests run parts of Synapse, including your changes, to see if anything
+was broken. They are slower than the linters but will typically catch more errors.
+
+```sh
+source ./env/bin/activate
+trial tests
+```
+
+If you wish to only run *some* unit tests, you may specify
+another module instead of `tests` - or a test class or a method:
+
+```sh
+source ./env/bin/activate
+trial tests.rest.admin.test_room tests.handlers.test_admin.ExfiltrateData.test_invite
+```
+
+If your tests fail, you may wish to look at the logs:
+
+```sh
+less _trial_temp/test.log
+```
+
+## Run the integration tests.
+
+The integration tests are a more comprehensive suite of tests. They
+run a full version of Synapse, including your changes, to check if
+anything was broken. They are slower than the unit tests but will
+typically catch more errors.
+
+The following command will let you run the integration test with the most common
+configuration:
+
+```sh
+$ docker run --rm -it -v /path/where/you/have/cloned/the/repository\:/src:ro -v /path/to/where/you/want/logs\:/logs matrixdotorg/sytest-synapse:py37
+```
+
+This configuration should generally cover  your needs. For more details about other configurations, see [documentation in the SyTest repo](https://github.com/matrix-org/sytest/blob/develop/docker/README.md).
+
 
-Before pushing new changes, ensure they don't produce linting errors. Commit any
-files that were corrected.
+# 9. Submit your patch.
+
+Once you're happy with your patch, it's time to prepare a Pull Request.
+
+To prepare a Pull Request, please:
+
+1. verify that [all the tests pass](#test-test-test), including the coding style;
+2. [sign off](#sign-off) your contribution;
+3. `git push` your commit to your fork of Synapse;
+4. on GitHub, [create the Pull Request](https://docs.github.com/en/github/collaborating-with-issues-and-pull-requests/creating-a-pull-request);
+5. add a [changelog entry](#changelog) and push it to your Pull Request;
+6. for most contributors, that's all - however, if you are a member of the organization `matrix-org`, on GitHub, please request a review from `matrix.org / Synapse Core`.
 
-Please ensure your changes match the cosmetic style of the existing project,
-and **never** mix cosmetic and functional changes in the same commit, as it
-makes it horribly hard to review otherwise.
 
 ## Changelog
 
@@ -156,24 +292,6 @@ directory, you will need both a regular newsfragment *and* an entry in the
 debian changelog. (Though typically such changes should be submitted as two
 separate pull requests.)
 
-## Documentation
-
-There is a growing amount of documentation located in the [docs](docs)
-directory. This documentation is intended primarily for sysadmins running their
-own Synapse instance, as well as developers interacting externally with
-Synapse. [docs/dev](docs/dev) exists primarily to house documentation for
-Synapse developers. [docs/admin_api](docs/admin_api) houses documentation
-regarding Synapse's Admin API, which is used mostly by sysadmins and external
-service developers.
-
-New files added to both folders should be written in [Github-Flavoured
-Markdown](https://guides.github.com/features/mastering-markdown/), and attempts
-should be made to migrate existing documents to markdown where possible.
-
-Some documentation also exists in [Synapse's Github
-Wiki](https://github.com/matrix-org/synapse/wiki), although this is primarily
-contributed to by community authors.
-
 ## Sign off
 
 In order to have a concrete record that your contribution is intentional
@@ -240,47 +358,36 @@ Git allows you to add this signoff automatically when using the `-s`
 flag to `git commit`, which uses the name and email set in your
 `user.name` and `user.email` git configs.
 
-## Continuous integration and testing
 
-[Buildkite](https://buildkite.com/matrix-dot-org/synapse) will automatically
-run a series of checks and tests against any PR which is opened against the
-project; if your change breaks the build, this will be shown in GitHub, with
-links to the build results. If your build fails, please try to fix the errors
-and update your branch.
+# 10. Turn feedback into better code.
+
+Once the Pull Request is opened, you will see a few things:
 
-To run unit tests in a local development environment, you can use:
+1. our automated CI (Continuous Integration) pipeline will run (again) the linters, the unit tests, the integration tests and more;
+2. one or more of the developers will take a look at your Pull Request and offer feedback.
 
-- ``tox -e py35`` (requires tox to be installed by ``pip install tox``)
-  for SQLite-backed Synapse on Python 3.5.
-- ``tox -e py36`` for SQLite-backed Synapse on Python 3.6.
-- ``tox -e py36-postgres`` for PostgreSQL-backed Synapse on Python 3.6
-  (requires a running local PostgreSQL with access to create databases).
-- ``./test_postgresql.sh`` for PostgreSQL-backed Synapse on Python 3.5
-  (requires Docker). Entirely self-contained, recommended if you don't want to
-  set up PostgreSQL yourself.
+From this point, you should:
 
-Docker images are available for running the integration tests (SyTest) locally,
-see the [documentation in the SyTest repo](
-https://github.com/matrix-org/sytest/blob/develop/docker/README.md) for more
-information.
+1. Look at the results of the CI pipeline.
+   - If there is any error, fix the error.
+2. If a developer has requested changes, make these changes and let us know if it is ready for a developer to review again.
+3. Create a new commit with the changes.
+   - Please do NOT overwrite the history. New commits make the reviewer's life easier.
+   - Push this commits to your Pull Request.
+4. Back to 1.
 
-## Updating your pull request
+Once both the CI and the developers are happy, the patch will be merged into Synapse and released shortly!
 
-If you decide to make changes to your pull request - perhaps to address issues
-raised in a review, or to fix problems highlighted by [continuous
-integration](#continuous-integration-and-testing) - just add new commits to your
-branch, and push to GitHub. The pull request will automatically be updated.
+# 11. Find a new issue.
 
-Please **avoid** rebasing your branch, especially once the PR has been
-reviewed: doing so makes it very difficult for a reviewer to see what has
-changed since a previous review.
+By now, you know the drill!
 
-## Notes for maintainers on merging PRs etc
+# Notes for maintainers on merging PRs etc
 
 There are some notes for those with commit access to the project on how we
 manage git [here](docs/dev/git.md).
 
-## Conclusion
+# Conclusion
 
 That's it! Matrix is a very open and collaborative project as you might expect
 given our obsession with open communication. If we're going to successfully