SUMO comes with a large set of tests, just browse them at sumo/tests. If you do not want to download all the tests with the complete sumo package you can use this form to download a single test. Paste the path to the test you like (e.g. sumo/tests/sumo/extended/rerouter/use_routing_device) into the form and get a zip containing all the files. You can also paste the complete URL from GitHub, you do not need to cut off the prefix.
You do not need to fill the Application field unless this page complains about a non-unique application. If this is the case you need to choose the variant to extract (like "sumo" or "meso") and fill it in. You can also use this site as a web service by calling it like https://sumo.dlr.de/extractTest.php?path=path/to/test.