### Question:
RuleServiceImpl implements RuleService { @Override public Collection<String> getAllAlexaKeywords() { return ruleRepository.getAllAlexaKeywords(); }  @Override List<Rule> getAllRulesByTargetType(String targetType); @Override List<RuleProjection> getAllRulesByTargetTypeName(String targetType); @Override List<RuleProjection> getAllRulesByTargetTypeAndNotInRuleIdList(final String targetType, final List<String> ruleIdList); @Override List<RuleProjection> getAllRulesByTargetTypeAndRuleIdList(final String targetType, final List<String> ruleIdList); @Override Rule getByRuleId(String ruleId); @Override Page<Rule> getRules(final String searchTerm, final int page, final int size); @Override Collection<String> getAllAlexaKeywords(); @Override Collection<String> getAllRuleIds(); @Override String createRule(final MultipartFile fileToUpload, final CreateUpdateRuleDetails ruleDetails, final String userId); @Override String updateRule(MultipartFile fileToUpload, CreateUpdateRuleDetails updateRuleDetails, String userId); @Override String invokeRule(String ruleId, List<Map<String, Object>> ruleOptionalParams); @Override String enableDisableRule(final String ruleId, final String action, final String userId); @Override Map<String, Object> invokeAllRules(List<String> ruleIds); boolean isRuleIdExits(String ruleId); @Override List<RuleCategory> getAllRuleCategories();  }### Answer:
@Test public void getAllAlexaKeywordsTest() { Collection<String> alexaKeywords = Lists.newArrayList(); alexaKeywords.add("Alexa1"); alexaKeywords.add("Alexa2"); when(ruleService.getAllAlexaKeywords()).thenReturn(alexaKeywords); assertThat(ruleRepository.getAllAlexaKeywords().size(), is(2)); }