@Test
  public void testNoRules() throws IOException {
    // Override what is in the configuration with the name of a non-existent file!
    HTU.getConfiguration().set(
      HeterogeneousRegionCountCostFunction.HBASE_MASTER_BALANCER_HETEROGENEOUS_RULES_FILE,
      "non-existent-file!");
    this.costFunction = new HeterogeneousRegionCountCostFunction(HTU.getConfiguration());
    this.costFunction.loadRules();
    assertEquals(0, this.costFunction.getNumberOfRulesLoaded());
  }
Make a file for rules that is inside a temporary test dir named for the method so it doesn't
clash w/ other rule files.
hbase-balancer/src/test/java/org/apache/hadoop/hbase/master/balancer/TestStochasticLoadBalancerHeterogeneousCostRules.java