How to test a cluster of microservices?
If nothing exists to easily mock Consul, have you considered spinning up a Consul service along with your other microservices? Consul can run in Docker, so this should be fairly straightforward if you use docker-compose and your apps can be configured to point to a different Consul endpoint.

Once your docker-compose is configured to spin up all the infrastructure/microservices required for your test, you will be able to use whatever tools you're familiar with to test your microservices, e.g. Selenium.