#2815 do not broadcast heartbeat proposal when we are non-validator (#2819)

* #2815 do not broadcast heartbeat proposal when we are non-validator

* #2815 adding preliminary changelog entry

* #2815 cosmetics and added test

* #2815 missed a little detail

- it's enough to call getAddress() once here

* #2815 remove debug logging from tests

* #2815 OK. I seem to be doing something fundamentally wrong here

* #2815 next iteration of proposalHeartbeat tests

- try and use "ensure" pattern in common_test

* 2815 incorporate review comments

consensus/common_test.go

@@ -425,6 +425,20 @@ func ensureNewRound(roundCh <-chan interface{}, height int64, round int) {
 	}
 }
 
+func ensureProposalHeartbeat(heartbeatCh <-chan interface{}) {
+	select {
+	case <-time.After(ensureTimeout):
+		panic("Timeout expired while waiting for ProposalHeartbeat event")
+	case ev := <-heartbeatCh:
+		heartbeat, ok := ev.(types.EventDataProposalHeartbeat)
+		if !ok {
+			panic(fmt.Sprintf("expected a *types.EventDataProposalHeartbeat, "+
+				"got %v. wrong subscription channel?",
+				reflect.TypeOf(heartbeat)))
+		}
+	}
+}
+
 func ensureNewTimeout(timeoutCh <-chan interface{}, height int64, round int, timeout int64) {
 	timeoutDuration := time.Duration(timeout*3) * time.Nanosecond
 	ensureNewEvent(timeoutCh, height, round, timeoutDuration,