Multiple failures are caused by
java.lang.NoClassDefFoundError: Could not initialize class org.jboss.tools.jsf.ui.JsfUiPlugin$PluginHolder
because of class cast exception at
(JsfUiPlugin)Platform.getPlugin(PLUGIN_ID)
since platform returned DefaultPlugin instead of JsfUiPlugin.

Method Platform.getPlugin(String) is deprecated and probably works in the latest Eclipse not as before. Multiple failures (80 and more) started with build #52 on October 25, 2015. Build #51had only few failed tests.
Pattern of initializing JsfUiPlugin is very uncommon and we should change it to the regular pattern in which static plugin instance is set in the constructor.