[PAN-2529] subscribing to sync events should receive false when in sync (#1240)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

ethereum/core/src/main/java/tech/pegasys/pantheon/ethereum/core/SyncStatus.java

@@ -38,6 +38,10 @@ public final class SyncStatus {
     return highestBlock;
   }
 
+  public boolean inSync() {
+    return currentBlock == highestBlock;
+  }
+
   @Override
   public boolean equals(final Object o) {
     if (this == o) {

ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/websocket/subscription/syncing/SyncingSubscriptionService.java

@@ -35,7 +35,12 @@ public class SyncingSubscriptionService {
     final List<Subscription> syncingSubscriptions =
         subscriptionManager.subscriptionsOfType(SubscriptionType.SYNCING, Subscription.class);
 
-    syncingSubscriptions.forEach(
-        s -> subscriptionManager.sendMessage(s.getId(), new SyncingResult(syncStatus)));
+    if (syncStatus.inSync()) {
+      syncingSubscriptions.forEach(
+          s -> subscriptionManager.sendMessage(s.getId(), new NotSynchronisingResult()));
+    } else {
+      syncingSubscriptions.forEach(
+          s -> subscriptionManager.sendMessage(s.getId(), new SyncingResult(syncStatus)));
+    }
   }
 }

ethereum/jsonrpc/src/test/java/tech/pegasys/pantheon/ethereum/jsonrpc/websocket/subscription/syncing/SyncingSubscriptionServiceTest.java

@@ -53,11 +53,24 @@ public class SyncingSubscriptionServiceTest {
     final SyncingSubscription subscription = new SyncingSubscription(9L, SubscriptionType.SYNCING);
     when(subscriptionManager.subscriptionsOfType(any(), any()))
         .thenReturn(Lists.newArrayList(subscription));
-    final SyncStatus syncStatus = new SyncStatus(0L, 1L, 1L);
+    final SyncStatus syncStatus = new SyncStatus(0L, 1L, 3L);
     final SyncingResult expectedSyncingResult = new SyncingResult(syncStatus);
 
     syncStatusListener.onSyncStatus(syncStatus);
 
     verify(subscriptionManager).sendMessage(eq(subscription.getId()), eq(expectedSyncingResult));
   }
+
+  @Test
+  public void shouldSendNotSyncingStatusWhenReceiveSyncStatusAtHead() {
+    final SyncingSubscription subscription = new SyncingSubscription(9L, SubscriptionType.SYNCING);
+    when(subscriptionManager.subscriptionsOfType(any(), any()))
+        .thenReturn(Lists.newArrayList(subscription));
+    final SyncStatus syncStatus = new SyncStatus(0L, 1L, 1L);
+
+    syncStatusListener.onSyncStatus(syncStatus);
+
+    verify(subscriptionManager)
+        .sendMessage(eq(subscription.getId()), any(NotSynchronisingResult.class));
+  }
 }