Please keep in mind that what is described below is valid only if you have a Solr instance with a single core. Thanks to +Alessandro Benedetti for alerting me on this sneaky stuff ;)I recently migrated a project  from Solr 4.x to Solr 5.x (actually Solr 5.3.1), and the only annoying stuff has been a (small) refactoring of my integration test suite.
Previously, I always used the cool Maven Cargo plugin for running and stopping Solr (ehmm Jetty with a solr.war deployed in) before and after my suite. For those who are still using Solr 4.x here  there's the configuration. It is just a matter of a single command:
> maven install
Unfortunately, Solr 5.x is no longer (formally) a web application, so I'd need to find another way to run the integration suite. After googling a bit I wasn't able to find a solution so I asked to myself : "How do Solr folks run their integration tests?" and I find this artifact  on the Maven repository: solr-test-framework..."well, the name sounds good", I said.
Effectively, I found a lot of already built things that do a lot of stuff for you. In my case, I only had to change a bit my integration suite superclass; actually a simple change because I had to extend from org.apache.solr.SolrJettyTestBase.
This class provides methods for starting and stopping Jetty (yes, still Jetty because even formally Solr is no longer a JEE web application, actually it still is, and it comes bundled with a Jetty, which provides the HTTP connectivity). Starting the servlet container in your methods is up to you, by means of the several createJetty(...) static methods. Instead, that class provides a @BeforeClass annotated method which stops Jetty at the end of the execution, of course in case it has been previously started.
You can find my code here , any feedback is warmly welcome ;)
 pom.xml using the Maven Cargo plugin and Solr 4.10.4
 SolRDF test superclass using the solr-test-framework