NullPointerException when MockMvc performed in unit test

Question

I'm trying to write a Java unit test but not sure where I'm going wrong. Likely a lack of understanding.

This is my test so far:

@Test
public void getURL() throws Exception {
    when(restTemplate.exchange(
            anyString(), eq(HttpMethod.GET), httpEntityCapture.capture(),
            ArgumentMatchers.<ParameterizedTypeReference<List<MyAP>>>any(),
            urlParamCapture.capture())).thenReturn(new ResponseEntity<>(myAPs, HttpStatus.OK));
    when(restTemplate.exchange(
            anyString(), eq(HttpMethod.GET), httpEntity2Capture.capture(),
            eq(ReissueCert.class), urlParam2Capture.capture()))
            .thenReturn(new ResponseEntity<>(reissueCert, HttpStatus.OK));
    MvcResult result = mockMvc.perform(get(Endpoints.FWD_URL, "123")
            .contentType(MediaType.APPLICATION_FORM_URLENCODED)
            .header("iv-user", email))
            .andExpect(status()
                    .isOk())
            .andReturn();
    assertEquals("Correct email sent", email, urlParamCapture.getValue());
    assertEquals("Correct dob", "07-09-1981", urlParam2Capture.getValue());
    assertEquals("Correct policy number", "123", urlParam3Capture.getValue());

}

When I run this I get a NullPointerException. The exception is from this line in my code:

ReissueURL reissue = docHelper.getURL(accountService.getAccountDetails(req.getHeader(Constants.IVUSER)).getId().toString(), accountService.getAccountDetails(req.getHeader(Constants.IVUSER)).getDob(), policy);

I think the problem is that no value ever exists for req.getHeader(Constants.IVUSER)).getDob() in my test. I'm not certain though and I'm not sure what to do next.

My debugger also shows this:

Cannot find local variable 'urlParam2Capture'

Also, FYI a get on Endpoints.FWD should return something like this:

{
    "reissueURL": "https://hostname/product/logon.htm/product/reissue.htm?clientId=4609&dob=01-01-1980&policyNumber=123"
}

Here's the full stack trace:

14:13:15.005 INFO [service.name:myapi,,,] [main] INFO o.s.s.c.ThreadPoolTaskExecutor – Shutting down ExecutorService 'applicationTaskExecutor'

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) at javax.servlet.http.HttpServlet.service(HttpServlet.java:645) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:72) at javax.servlet.http.HttpServlet.service(HttpServlet.java:750) at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at brave.servlet.TracingFilter.doFilter(TracingFilter.java:67) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at ie.avis.myapi.config.TivoliAuthenticationFilter.doFilter(TivoliAuthenticationFilter.java:46) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:118) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:158) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at ie.avis.myapi.config.TivoliAuthenticationFilter.doFilter(TivoliAuthenticationFilter.java:46) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:92) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.cloud.sleuth.instrument.web.ExceptionLoggingFilter.doFilter(ExceptionLoggingFilter.java:50) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at brave.servlet.TracingFilter.doFilter(TracingFilter.java:84) at org.springframework.cloud.sleuth.instrument.web.LazyTracingFilter.doFilter(TraceWebServletAutoConfiguration.java:138) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:109) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:183) at ie.avis.myapi.controller.DocsControllerIT.getReissueCertURL(DocsControllerIT.java:283) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74) at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75) at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86) at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70) Caused by: java.lang.NullPointerException at ie.avis.myapi.service.account.AccountServiceReal.getAccountDetails(AccountServiceReal.java:72) at ie.avis.myapi.service.account.AccountServiceReal$$FastClassBySpringCGLIB$$6c77a5a0.invoke() at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:687) at ie.avis.myapi.service.account.AccountServiceReal$$EnhancerBySpringCGLIB$$bc8047e0.getAccountDetails() at ie.avis.myapi.controller.DocsController.getReissueCertURL(DocsController.java:148) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ... 96 more

My NullPointerException comes from the getAccountDetails method:

public AccountDetails getAccountDetails(String username) {
    HttpHeaders headers = createHeaders();
    headers.add(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_VALUE);
    HttpEntity<String> request = new HttpEntity<>(headers);
    ResponseEntity<AccountDetails> response = restTemplate.exchange(accountAPIEndpoint + Constants.GET_ACCOUNT,
            HttpMethod.GET, request, AccountDetails.class, username);
    if (response.getStatusCode().is2xxSuccessful()) {
        LOG.debug("Request successful. Returning AccountDetails.");
        return response.getBody();
    } else {
        return null;
    }
}

I guess I need to mock an AccountDetails object for this. Is that correct and if so, how do I do that?

I'm attempting something like this:

@Before
public void setUp() {
    account1 = Account.builder().id(1L).username("foo").dob("07-09-1981").build();
}

...

public void getURL() throws Exception {
    when(restTemplate.exchange(
            anyString(), eq(HttpMethod.GET), httpEntityCapture.capture(),
            ArgumentMatchers.<ParameterizedTypeReference<List<MyAP>>>any(),
            urlParamCapture.capture())).thenReturn(new ResponseEntity<>(myAPs, HttpStatus.OK));
    when(restTemplate.exchange(
            anyString(), eq(HttpMethod.GET), httpEntity2Capture.capture(),
            eq(ReissueCert.class), urlParam2Capture.capture()))
            .thenReturn(new ResponseEntity<>(reissueCert, HttpStatus.OK));
    
    when(accountServiceReal.getAccountDetails("foo")).thenReturn(accountDetails);
    MvcResult result = mockMvc.perform(get(Endpoints.FWD_URL, "123")
            .contentType(MediaType.APPLICATION_FORM_URLENCODED)
            .header("iv-user", email))
            .andExpect(status()
                    .isOk())
            .andReturn();
    assertEquals("Correct email sent", email, urlParamCapture.getValue());
    assertEquals("Correct dob", "07-09-1981", urlParam2Capture.getValue());
    assertEquals("Correct policy number", "123", urlParam3Capture.getValue());

}

It's not working yet. Is this the correct approach though?