### Question:
FairScheduler extends
    AbstractYarnScheduler<FSAppAttempt, FSSchedulerNode> { @Override public void reinitialize(Configuration conf, RMContext rmContext) throws IOException { try { allocsLoader.reloadAllocations(); } catch (Exception e) { LOG.error("Failed to reload allocations file", e); } } FairScheduler(); FairSchedulerConfiguration getConf(); QueueManager getQueueManager(); synchronized RMContainerTokenSecretManager getContainerTokenSecretManager(); synchronized ResourceWeights getAppWeight(FSAppAttempt app); Resource getIncrementResourceCapability(); double getNodeLocalityThreshold(); double getRackLocalityThreshold(); long getNodeLocalityDelayMs(); long getRackLocalityDelayMs(); boolean isContinuousSchedulingEnabled(); synchronized int getContinuousSchedulingSleepMs(); Clock getClock(); FairSchedulerEventLog getEventLog(); @Override Allocation allocate(ApplicationAttemptId appAttemptId,
      List<ResourceRequest> ask, List<ContainerId> release,
      List<String> blacklistAdditions, List<String> blacklistRemovals); FSAppAttempt getSchedulerApp(ApplicationAttemptId appAttemptId); @Override ResourceCalculator getResourceCalculator(); @Override QueueMetrics getRootQueueMetrics(); @Override void handle(SchedulerEvent event); @Override void recover(RMState state); synchronized void setRMContext(RMContext rmContext); @Override void serviceInit(Configuration conf); @Override void serviceStart(); @Override void serviceStop(); @Override void reinitialize(Configuration conf, RMContext rmContext); @Override QueueInfo getQueueInfo(String queueName, boolean includeChildQueues,
      boolean recursive); @Override List<QueueUserACLInfo> getQueueUserAclInfo(); @Override int getNumClusterNodes(); @Override synchronized boolean checkAccess(UserGroupInformation callerUGI,
      QueueACL acl, String queueName); AllocationConfiguration getAllocationConfiguration(); @Override List<ApplicationAttemptId> getAppsInQueue(String queueName); @Override synchronized String moveApplication(ApplicationId appId,
      String queueName); @Override synchronized void updateNodeResource(RMNode nm, 
      ResourceOption resourceOption); @Override EnumSet<SchedulerResourceTypes> getSchedulingResourceTypes(); @Override Set<String> getPlanQueues(); @Override void setEntitlement(String queueName,
      QueueEntitlement entitlement); @Override void removeQueue(String queueName); static final Resource CONTAINER_RESERVED; }### Answer:
@Test public void testDefaultRuleInitializesProperlyWhenPolicyNotConfigured() throws IOException { conf.set(FairSchedulerConfiguration.ALLOCATION_FILE, ALLOC_FILE); conf.setBoolean(FairSchedulerConfiguration.ALLOW_UNDECLARED_POOLS, false); PrintWriter out = new PrintWriter(new FileWriter(ALLOC_FILE)); out.println("<?xml version=\"1.0\"?>"); out.println("<allocations>"); out.println("</allocations>"); out.close(); scheduler.init(conf); scheduler.start(); scheduler.reinitialize(conf, resourceManager.getRMContext()); List<QueuePlacementRule> rules = scheduler.allocConf.placementPolicy .getRules(); for (QueuePlacementRule rule : rules) { if (rule instanceof Default) { Default defaultRule = (Default) rule; assertNotNull(defaultRule.defaultQueueName); } } }