@Override
    public boolean isLeader(String group) {
        Node node = raftServer.findNodeByGroup(group);
        if (node == null) {
            throw new NoSuchRaftGroupException(group);
        }
        return node.isLeader();
    }
@Test
    void testIsLeader() {
        raftProtocol.isLeader(groupId);
        verify(serverMock).findNodeByGroup(groupId);
        verify(nodeMock).isLeader();
    }