None

java.lang.AssertionError: null
	at org.junit.Assert.fail(Assert.java:86)
	at org.junit.Assert.assertTrue(Assert.java:41)
	at org.junit.Assert.assertNotNull(Assert.java:621)
	at org.junit.Assert.assertNotNull(Assert.java:631)
	at org.apache.spark.launcher.LauncherServerSuite.testCommunication(LauncherServerSuite.java:98)