No special configuration is required for development.
Run yarn workspace taskcluster-purge-cache test to run the tests.
Some of the tests will be skipped without additional credentials, but it is fine to make a pull request as long as no tests fail.
To run all tests, you will need appropriate Taskcluster credentials.
Using taskcluster-cli, run eval $(taskcluster signin --scope assume:project:taskcluster:tests:taskcluster-purge-cache), then run the tests again.