### Question:
DefaultConfigurationAccessor implements ConfigurationAccessor { @Override public Optional<ConfigurationModel> getConfigurationById(Long id) throws AlertDatabaseConstraintException { if (id == null) { throw new AlertDatabaseConstraintException(NULL_CONFIG_ID); } Optional<DescriptorConfigEntity> optionalDescriptorConfigEntity = descriptorConfigsRepository.findById(id); if (optionalDescriptorConfigEntity.isPresent()) { DescriptorConfigEntity descriptorConfigEntity = optionalDescriptorConfigEntity.get(); return Optional .of(createConfigModel(descriptorConfigEntity.getDescriptorId(), descriptorConfigEntity.getId(), descriptorConfigEntity.getCreatedAt(), descriptorConfigEntity.getLastUpdated(), descriptorConfigEntity.getContextId())); } return Optional.empty(); } @Autowired  DefaultConfigurationAccessor(RegisteredDescriptorRepository registeredDescriptorRepository, DescriptorTypeRepository descriptorTypeRepository, DefinedFieldRepository definedFieldRepository,
        DescriptorConfigRepository descriptorConfigsRepository, ConfigGroupRepository configGroupRepository, ConfigContextRepository configContextRepository, FieldValueRepository fieldValueRepository,
        EncryptionUtility encryptionUtility); @Override List<ConfigurationJobModel> getAllJobs(); @Override Optional<ConfigurationJobModel> getJobById(UUID jobId); @Override List<ConfigurationJobModel> getJobsByFrequency(FrequencyType frequency); @Override ConfigurationJobModel createJob(Collection<String> descriptorNames, Collection<ConfigurationFieldModel> configuredFields); @Override ConfigurationJobModel updateJob(UUID jobId, Collection<String> descriptorNames, Collection<ConfigurationFieldModel> configuredFields); @Override void deleteJob(UUID jobId); @Override Optional<ConfigurationModel> getProviderConfigurationByName(String providerConfigName); @Override Optional<ConfigurationModel> getConfigurationById(Long id); @Override List<ConfigurationModel> getConfigurationsByDescriptorKey(DescriptorKey descriptorKey); @Override List<ConfigurationModel> getConfigurationsByDescriptorType(DescriptorType descriptorType); @Override List<ConfigurationModel> getChannelConfigurationsByFrequency(FrequencyType frequencyType); @Override List<ConfigurationModel> getConfigurationsByDescriptorKeyAndContext(DescriptorKey descriptorKey, ConfigContextEnum context); @Override ConfigurationModel createConfiguration(DescriptorKey descriptorKey, ConfigContextEnum context, Collection<ConfigurationFieldModel> configuredFields); @Override List<ConfigurationModel> getConfigurationsByDescriptorNameAndContext(String descriptorName, ConfigContextEnum context); @Override ConfigurationModel updateConfiguration(Long descriptorConfigId, Collection<ConfigurationFieldModel> configuredFields); @Override void deleteConfiguration(ConfigurationModel configModel); @Override void deleteConfiguration(Long descriptorConfigId); static final String EXCEPTION_FORMAT_DESCRIPTOR_KEY_IS_NOT_VALID; }### Answer:
@Test public void getConfigurationByIdEmptyTest() throws Exception { Mockito.when(descriptorConfigRepository.findById(Mockito.any())).thenReturn(Optional.empty()); DefaultConfigurationAccessor configurationAccessor = new DefaultConfigurationAccessor(null, null, null, descriptorConfigRepository, null, null, null, null); Optional<ConfigurationModel> configurationModelOptional = configurationAccessor.getConfigurationById(1L); assertFalse(configurationModelOptional.isPresent()); }
@Test public void getConfigurationByIdNullTest() throws Exception { DefaultConfigurationAccessor configurationAccessor = new DefaultConfigurationAccessor(null, null, null, null, null, null, null, null); try { configurationAccessor.getConfigurationById(null); fail("Null id did not throw expected AlertDatabaseConstraintException."); } catch (AlertDatabaseConstraintException e) { assertNotNull(e); } }