java - Android JUnit: assert inside the handler -

i trying make assert inside of handler without success. tried execute threads, runnables, etc. next code 1 example:

public class servertest extends androidtestcase {     private final string tag = this.getclass().getsimplename();      private final int ack = 1;      public void testsendtoserver(){         final serverstub server = new serverstub();                  final countdownlatch signal = new countdownlatch(1);                  new thread(new runnable() {                          handler handler = new handler(new handler.callback() {                 @override                 public boolean handlemessage(message msg) {                     // log never appear                     log.w(tag, "handlemessage(message "+msg+")");                     assertequals(ack, msg.what);                      signal.countdown();                     return true;                 }             });              @override             public void run() {                 // log never appear                 log.w(tag, "senttoserver()");                 server.senttoserver(handler);                            }         }).start();           try {             signal.await(15, timeunit.seconds);         } catch (interruptedexception e) {             e.printstacktrace();         }                    //this assert fails         assertequals(0, signal.getcount());     }      class serverstub{         private final string tag = this.getclass().getsimplename();           public void senttoserver(handler handler){             message message = new message();             message.what = ack;              log.i(tag, "ack_received");             handler.sendmessage(message);         }     } } 

i want test method class doesn't return nothing, "do something" , return response using handler.

i execute test case testsendtoserver() next intention:

in test serverstub created has method senttoserver(handler handler). in method send "ack" message handler. after create countdownlatch signal = new countdownlatch(1); call signal.countdown(); inside handler handlemessage(message msg) method know if executed.

continue test, create new thread handler created , senttoserver(handler handler) called. inside handler assertequals(ack, msg.what); called need know if serverstub sent me "ack".

main thread waiting 15 seconds or signal.countdown(); executed. call assertequals(0, signal.getcount()); check if handler executed.

however handler handlemessage(message msg) method never executed.

i read other posts , tried lot of examples, never found answer. possible that?

more information: trying create handler inside thread, this:

new thread() {         @override         public void run() {             log.w(tag, "thread run");             handler handler = new handler(new handler.callback() {                 ...             }         }     }.start(); 

the log "thread run" printed after "test run failed: instrumentation run failed due 'java.lang.runtimeexception'".