Add some notes about testing to the documentation

docs/source/development.rst

@@ -4,5 +4,6 @@ Development
 .. toctree::
    :maxdepth: 4
 
-   development.quick_environment.rst
+   development.quick_environment.md
+   development.testing.md
    modules

docs/source/development.testing.md

@@ -0,0 +1,29 @@
+# Testing
+
+All tests require an active setup of the Data Tracker via docker-compose and test data in the database (See [System for development](development.quick_environment.md))
+
+Most tests are not deterministic and do not restore the state of the db afterwards.
+
+## Backend
+
+The tests are found in `backend/tests`. Use the same `venv` used to add data to the database.
+
+From the root of the repository:
+
+```
+PYTHONPATH=backend pytest backend
+```
+
+## Frontend
+
+Frontend testing is implemented using the end-to-end testing solution Nightwatch.
+
+Go to `test/nighwatch` and run `yarn install` to install the required packages.
+
+Nightwatch can use multiple different browsers, but the tests have only been confirmed to work with Chrome.
+
+To run the tests (in the `test/nighwatch` folder):
+
+```
+npx nightwatch collection.js --env chrome
+```