fix: make broadcast batching test deterministic (#2130)

sdk-utils/broadcast/broadcast_test.go

@@ -308,12 +308,15 @@ func TestInBatches(t *testing.T) {
 					assert.Equal(t, msgs[0].String(), response.Events[0].Type)
 				}()
 				<-broadcastCalled
+				ensureGoRoutineIsCalled := &sync.WaitGroup{}
+				ensureGoRoutineIsCalled.Add(20)
 				// accumulate msgs in the backlog
-				for i := 0; i < 9; i++ {
+				for i := 0; i < 20; i++ {
 					wg.Add(1)
 					go func() {
 						defer wg.Done()
 						msgs := randomMsgs(1)
+						ensureGoRoutineIsCalled.Done()
 						response, err := batched.Broadcast(context.Background(), msgs...)
 						assert.NoError(t, err)
 						// make sure the expected msg is part of the response
@@ -322,9 +325,13 @@ func TestInBatches(t *testing.T) {
 								func(event abci.Event) bool { return msgs[0].String() == event.Type }))
 					}()
 				}
+				// with this waitgroup we ensure that all goroutines that broadcast a message are at least started.
+				// Without it, the unblockBroadcast channel might be closed before the main thread relinquishes control and
+				// the messages would trickle in one after the other without batching
+				ensureGoRoutineIsCalled.Wait()
 				close(unblockBroadcast)
 				wg.Wait()
-				assert.Less(t, len(broadcaster.BroadcastCalls()), 10)
+				assert.Less(t, len(broadcaster.BroadcastCalls()), 20)
 			}),
 	).Run(t)
 }