DZone

Sometimes when you are running your tests on your CI environment, you want to run tests in parallel. This parallelism is programmed in build tools such as Maven or Gradle or by using Jenkins plugin. 

If you are using Docker as a testing tool for providing external dependencies to the application (for example databases, mail servers, FTP servers) you might find a big problem, and it is that in Docker Host, when running tests in parallel, all of them are going to try to start a container with the same name, so when you start the second test (in parallel) you will get a failure regarding a conflict container name because of Docker Host trying to start two containers with the same name or having the same binding port in two containers.

Source: DZone