Update DEVELOPERS.md

DEVELOPERS.md

@@ -22,4 +22,4 @@ As a core component (to run tests the integration must be mounted under core com
 
 To get the simulator to work `/etc/hosts` needs to be modified to specify `127.0.0.1 localhost api.solcast.com.au` (use sudo). For a quick start, `cd config/custom_components/solcast_solar/sim` and execute `python3 -u wsgi.py --limit 5000 --no429`, which gets 5,000 API calls max, and no 'too busy' errors generated on the hour. (`python3 -u wsgi.py --help` for options, or inspect `wsgi.py` for doco.) Note that if the integration or simulator has never been started then dependencies will not yet be installed. The simulator will `pip install` missing dependencies and also create a new self-signed certificate. /etc/hosts is inspected but not modified automatically.
 
-The tests will show up at `tests/components/solcast_solar`. `cd` to there and execute `pytest`. To inspect logging, `pytest -o log_cli=true --log-cli-level=DEBUG`. Additional test contributions will be most welcome.
+The tests will show up at `tests/components/solcast_solar`. `cd` to there and execute `pytest`. To inspect logging, `pytest -o log_cli=true --log-cli-level=DEBUG`. For a test coverage report, `pytest --cov=homeassistant.components.solcast_solar --cov-report term-missing -vv`. Additional test contributions will be most welcome.