public void testMergeRequirements_findsDuplicates() {
   Compiler compiler = createCompiler();
   ErrorManager errorManager = new BlackHoleErrorManager();
   compiler.setErrorManager(errorManager);
   ConformanceConfig.Builder builder = ConformanceConfig.newBuilder();
   builder.addRequirementBuilder().addWhitelist("x").addWhitelist("x");
   CheckConformance.mergeRequirements(compiler, ImmutableList.of(builder.build()));
   assertEquals(1, errorManager.getErrorCount());
 }
 public void testMergeRequirements() {
   Compiler compiler = createCompiler();
   ConformanceConfig.Builder builder = ConformanceConfig.newBuilder();
   builder.addRequirementBuilder().setRuleId("a").addWhitelist("x").addWhitelistRegexp("m");
   builder.addRequirementBuilder().setExtends("a").addWhitelist("y").addWhitelistRegexp("n");
   List<Requirement> requirements =
       CheckConformance.mergeRequirements(compiler, ImmutableList.of(builder.build()));
   assertThat(requirements).hasSize(1);
   Requirement requirement = requirements.get(0);
   assertEquals(2, requirement.getWhitelistCount());
   assertEquals(2, requirement.getWhitelistRegexpCount());
 }