After a change in Hadoop's Configuration class (introduced parser restriction) majority of the integration tests started failing with an error message:
AssertionError: Auth User is not Kerberized <user> (auth:SIMPLE) -security has already been set up with the wrong authentication method. This can occur if ** a file system has already been created prior to the loading of the security configuration
It is most likely because of the early initialisation of the Hadoop configuration. The base class of the Slider integration tests loads the Slider client configuration (slider-client.xml) using Hadoop’s Configuration class, which contains a static initialiser block. When this block gets executed, the settings from the core-default.xml is loaded with SIMPLE authentication, but the core-site.xml containing Kerberos as authentication is not available on the classpath. During the load of the configuration files (because of the mentioned change above), Hadoop implicitly logs in the test user with SIMPLE authentication and later when the tests try to authenticate the same user with the Kerberos keytab it throws an error.
The tests could be fixed by adding the actual *-site.xml files to the classpath in the pom.xml of slider-funtest (using <additionalClasspathElements> for the maven-failsafe-plugin).