Trying to test some stuff

RestTemplateConfiguration.java

@Configuration
public class RestTemplateConfiguration {
  public static final String REST_TEMPLATE_NAME = "someRestTemplate";

  @Autowired
  private AppConfig appConfig;

  @Value("${props.useProxy})
  private boolean useProxy;

  @Bean(name = REST_TEMPLATE_NAME)
  public RestTemplate restTemplate(RestTemplateBuilder builder) {
    return builder
      .rootUri("")
      .requestFactory(this::getHttpClientFactory) // -> NPE Here
      .interceptors(getInterceptors())
      .errorHandler(getErrorHandlers())
      .build()
  }

  @Bean
  public HttpComponentsClientHttpRequestFactory getHttpClientFactory() {
    HttpComponentsClientHttpRequestFactory reqFactory = new HttpComponentsClientHttpRequestFactory(); 
    // ...does some SSL / Proxy stuff
    return reqFactory;
  }
}

RestTemplateConfigurationTest.java

@RunWith(SpringJUnit4ClassRunner.class)
public class RestTemplateConfigurationTest {
  @InjectMocks
  private RestTemplateConfiguration templateConfig;
  
  @Mock
  @Qualifier(RestTemplateConfiguration.REST_TEMPLATE_NAME)
  private RestTemplateBuilder builder;
  
  @BeforeEach
  public void setup() {
    initMocks(this);
  }
  
  @Test
  public void makeRequest_givenCustomHttpClientFactory_shouldRespondOK {
    RestTemplate template = new RestTemplateBuilder()
        .requestFactory(this.templateConfig::getHttpClientFactory)
        .build()
    
    ResponseEntity<String> response = null;
    boolean caughtException = false;
    try {
      response = template.exchange("https://google.com", HttpMethod.GET, null, String.class);
    } catch(Exception e) {
      caughtException = true;
    }
    
    assertEquals(false, caughtException, "Should not have exception");
    assertEquals(HttpStatus.OK, response.getStatusCode(), "Status should be OK.");
  }
}