+### RTL layout
+
+To test RTL layout using `ar` locale:
+
+```
+$ npm run dev -- --ar-locale
+```
+
+### Testing
+
+#### Unit/integration tests
+
+Your code contributions must pass the tests before they can be merged. Tests ensure most of the application behaves
+as expected and respect the syntax conventions. They will run upon PR submission as part of our CI, but running them beforehand yourself will get you faster feedback and save CI runner time for others.
+
+See the [dedicated documentation](/support/doc/development/tests.md) to run tests locally.
+
+#### Testing the federation of PeerTube servers
+
+Create a PostgreSQL user **with the same name as your username** in order to avoid using the *postgres* user.
+Then, we can create the databases (if they don't already exist):
+
+```
+$ sudo -u postgres createuser you_username --createdb
+$ createdb -O peertube peertube_test{1,2,3}
+```
+
+Build the application and flush the old tests data:
+
+```
+$ npm run build
+$ npm run clean:server:test
+```
+
+To run 3 nodes:
+
+```
+$ NODE_APP_INSTANCE=1 NODE_ENV=test npm start
+$ NODE_APP_INSTANCE=2 NODE_ENV=test npm start
+$ NODE_APP_INSTANCE=3 NODE_ENV=test npm start
+```
+
+Then you will get access to the three nodes at `http://localhost:900{1,2,3}`
+with the `root` as username and `test{1,2,3}` for the password.
+
+Instance configurations are in `config/test-{1,2,3}.yaml`.
+
+### Emails
+
+To test emails with PeerTube:
+
+ * Run [mailslurper](http://mailslurper.com/)
+ * Run PeerTube using mailslurper SMTP port: `NODE_CONFIG='{ "smtp": { "hostname": "localhost", "port": 2500, "tls": false } }' NODE_ENV=test npm start`
+
+## Plugins & Themes
+
+See the dedicated documentation: https://docs.joinpeertube.org/contribute-plugins