private void messengerAckAllInstallViewMessages() {
    // have the Messenger acknowledge all membership view messages so no-one is kicked out for
    // failure to respond
    when(messenger.send(isA(InstallViewMessage.class), isA(GMSMembershipView.class)))
        .thenAnswer((request) -> {
          InstallViewMessage<MemberIdentifier> installViewMessage = request.getArgument(0);
          for (MemberIdentifier recipient : installViewMessage.getRecipients()) {
            ViewAckMessage viewAckMessage =
                new ViewAckMessage(gmsJoinLeaveMemberId, installViewMessage.getView().getViewId(),
                    installViewMessage.isPreparing());
            viewAckMessage.setSender(recipient);
            gmsJoinLeave.processViewAckMessage(viewAckMessage);
          }
          return null;
        });
  }
Given a view with [A, B, C, D] where C is coordinator, a failed availability check on A
and a pending join request from E show that B becomes coordinator when C sends it a
Leave request and that E is allowed into the system and retains its view ID.
See GEODE-6570
geode-membership/src/integrationTest/java/org/apache/geode/distributed/internal/membership/gms/membership/GMSJoinLeaveJUnitTest.java