Develop Reference

Testing case where null should be returned using RestController with Mockito Fails

I want to test for a NullPointerException case that should be thrown by the controller that I am testing, but I always get NullPointerException error. I am trying to test the case where a user with a certain id is not found in the db. Is my way of doing that a valid way? If not, then how should I test that case? I haven't found any valuable info about this certain test case.
My Controller Test:
#RunWith(SpringJUnit4ClassRunner.class)
#WebMvcTest(value = UserController.class)
public class UserControllerTest
{
#Autowired
private MockMvc mockMvc;
#MockBean
private UserRepository userRepository;
#Test
public void testGetUserById_Status200_EmptyJsonPath() throws Exception
{
when(userRepository.findById(999)).thenReturn(null);
mockMvc.perform(get("/user/{user_id}", 999))
.andExpect(status().isNotFound());
verify(userRepository, times(1)).findById(999);
verifyNoMoreInteractions(userRepository);
}
My Controller:
#RestController
public class UserController
{
#Autowired
private UserRepository userRepository;
#RequestMapping(value = "/user/{user_id}")
public User getUser(#PathVariable int user_id) throws Exception
{
return userRepository.findById(user_id).orElse(null);
}
}
Error I get:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1013)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:71)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:166)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:133)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:133)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:133)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:133)
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:182)
at spring.controller.UserControllerTest.testGetUserById_Status200_EmptyJsonPath(UserControllerTest.java:111)
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:59)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
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.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:365)
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$4.run(ParentRunner.java:330)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:78)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:328)
at org.junit.runners.ParentRunner.access$100(ParentRunner.java:65)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:292)
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$3.evaluate(ParentRunner.java:305)
at org.junit.runners.ParentRunner.run(ParentRunner.java:412)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$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 spring.controller.UserController.getUser(UserController.java:35)
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:189)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
... 49 more

You can use
assertThatNullPointerException().isThrownBy(() -> userRepository.findById(999));
make sure you import following to use this method
import static org.assertj.core.api.Assertions.assertThatNullPointerException;

ModelMapper JUnit Mockito throws NullPointerException

I'm trying to test a method in service class which uses ModelMapper to convert entity to dto, but I'm getting NullPointerException at this line mapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT); in the service class.
Exception
java.lang.NullPointerException
at pro.budthapa.service.impl.StockCategoryServiceImpl.getStockCategoryByIdAndBusinessGroupId(StockCategoryServiceImpl.java:56)
at pro.budthapa.service.impl.StockCategoryServiceImplTest.WhenCategoryPresent_ShouldReturnCategory(StockCategoryServiceImplTest.java:81)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
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.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
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.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
Test Class
#RunWith(MockitoJUnitRunner.class)
public class StockCategoryServiceImplTest {
#Mock
private ModelMapper mapper;
#Mock
private StockCategoryRepository stockCategoryRepository;
#InjectMocks
private StockCategoryServiceImpl stockCategoryService;
#Before
public void setup() {
mapper = new ModelMapper();
}
#Test
public void WhenCategoryPresent_ShouldReturnCategory() throws Exception {
int bgId = 10;
int categoryId = 5;
StockCategory sc = new StockCategory();
sc.setCategoryId(categoryId);
sc.setBusinessGroupId(String.valueOf(bgId));
sc.setDescription("Test Item");
Mockito.when(stockCategoryRepository.findByCategoryIdAndBusinessGroupId(categoryId, String.valueOf(bgId))).thenReturn(Optional.of(sc));
StockCategoryDto result = stockCategoryService.getStockCategoryByIdAndBusinessGroupId(categoryId, bgId);
assertEquals(5, result.getCategoryId() );
assertEquals(10, result.getBusinessGroupId());
assertNotNull(result.getDescription());
Mockito.verify(stockCategoryRepository, Mockito.times(1)).findByCategoryIdAndBusinessGroupId(categoryId, String.valueOf(bgId));
}
}
Service Class
#Service
public class StockCategoryServiceImpl implements StockCategoryService {
private ModelMapper mapper;
private StockCategoryRepository stockCategoryRepository;
public StockCategoryServiceImpl(ModelMapper mapper, StockCategoryRepository stockCategoryRepository) {
this.mapper = mapper;
this.stockCategoryRepository = stockCategoryRepository;
}
#Override
public StockCategoryDto getStockCategoryByIdAndBusinessGroupId(int categoryId, int bgId) {
Optional<StockCategory> cat = stockCategoryRepository.findByCategoryIdAndBusinessGroupId(categoryId, String.valueOf(bgId));
if(cat.isPresent()) {
//getting NullPointerException at this line
mapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT);
return mapper.map(cat.get(), StockCategoryDto.class);
}
StockCategoryDto dto = new StockCategoryDto();
dto.setMessage("Category not found for given id: "+categoryId);
return dto;
}
}

You shouldn't reassign your mocked ModelMapper in setup method. Remove this method
And I can't find in your code mock definition for mapper.getConfiguration()
when(mapper.getConfiguration()).thenReturn(...)
You should tell it to mockito.

Cannot handle expected exception in integration test

I cannot pass test notFoundFoo since I get NestedServletException excpetion instead of expected FooNotFoundException exception.
What I do wrong in my test?
Controller:
#RestController
#RequestMapping("/api/foo")
public class FooController {
#Autowired
private FooService fooService;
#GetMapping("/{fooId}/status")
#ResponseStatus(HttpStatus.OK)
public PaymentStatus retrievePaymentStatus(#PathVariable String fooId) {
PaymentStatus paymentStatus = fooService.retrievePaymentStatus(fooId);
if (paymentStatus == null) {
throw new InvoiceNotFoundException();
}
// Preconditions.checkNotNull(paymentStatus, new FooNotFoundException());
return paymentStatus;
}
}
FooNotFoundException:
#ResponseStatus(value = HttpStatus.NOT_FOUND, reason = "Foo not found")
public class FooNotFoundException extends RuntimeException {
public FooNotFoundException() {
}
public FooNotFoundException(String message) {
super(message);
}
}
Tests:
#RunWith(SpringRunner.class)
#SpringBootTest(classes = App.class)
#AutoConfigureMockMvc
public class FooControllerTest {
#Autowired
FooRepository fooRepository;
#Autowired
BloomFilterManager bloomFilterManager;
#Autowired
private MockMvc mockMvc;
private MediaType CONTENT_TYPE = new MediaType(MediaType.APPLICATION_JSON.getType(),
MediaType.APPLICATION_JSON.getSubtype(),
Charset.forName("utf8"));
#Test
public void foundFooWithPaymentStatus() throws Exception {
Faker faker = new Faker();
Foo.PaymentStatus[] paymentStatuses = Foo.PaymentStatus.values();
Foo foo= fooRepository.save(new Foo(
faker.number().randomNumber(),
faker.lorem().word(),
faker.number().randomDigit(),
new BigDecimal(Math.random()),
paymentStatuses[faker.number().numberBetween(0, paymentStatuses.length)],
faker.date().between(new Date(), DateUtils.addDays(new Date(), 13))
));
bloomFilterManager.getBloomFilter().put(foo.getId());
RequestBuilder requestBuilder = MockMvcRequestBuilders
.get("/api/foo/{fooId}/status", foo.getId())
.accept(CONTENT_TYPE);
MvcResult result = mockMvc.perform(requestBuilder)
.andExpect(status().isOk())
.andExpect(content().contentType(CONTENT_TYPE))
.andReturn();
String expected = "\"" + foo.getPaymentStatus() + "\"";
assertEquals(expected, result.getResponse().getContentAsString());
}
#Test(expected = FooNotFoundException.class)
public void notFoundFoo() throws Exception {
String fooId = "100000000000000";
RequestBuilder requestBuilder = MockMvcRequestBuilders
.get("/api/foo/{fooId}/status", fooId)
.accept(CONTENT_TYPE);
mockMvc.perform(requestBuilder)
.andExpect(status().isNotFound())
.andExpect(content().contentType(CONTENT_TYPE));
}
Output:
java.lang.Exception: Unexpected exception, expected<org.learn.foo.exception.FooNotFoundException> but was<org.springframework.web.util.NestedServletException>
at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:28)
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:252)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
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:191)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
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$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$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: org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException: org.learn.foo.exception.FooNotFoundException
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:155)
at org.learn.integration.FooControllerTest.notFoundFoo(FooControllerTest.java:100)
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.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:19)
... 28 more
Caused by: java.lang.NullPointerException: org.learn.foo.exception.FooNotFoundException
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:900)
at org.learn.foo.controller.FooController.retrievePaymentStatus(FooController.java:22)
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:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
... 58 more
UPDATED:
MockHttpServletRequest:
HTTP Method = GET
Request URI = /api/foo/100000000000000/status
Parameters = {}
Headers = {Accept=[application/json;charset=UTF-8]}
Handler:
Type = org.wixanz.omniva.foo.controller.FooController
Method = public org.wixanz.omniva.foo.domain.foo$PaymentStatus org.wixanz.omniva.foo.controller.FooController.retrievePaymentStatus(java.lang.String)
Async:
Async started = false
Async result = null
Resolved Exception:
Type = org.wixanz.omniva.foo.exception.InvoiceNotFoundException
ModelAndView:
View name = null
View = null
Model = null
FlashMap:
Attributes = null
MockHttpServletResponse:
Status = 404
Error message = Foo not found
Headers = {}
Content type = null
Body =
Forwarded URL = null
Redirected URL = null
Cookies = []
java.lang.Exception: Unexpected exception, expected<org.wixanz.omniva.foo.exception.FooNotFoundException> but was<java.lang.AssertionError>
at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:28)
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:252)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
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:191)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
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$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$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.AssertionError: Content type not set
at org.springframework.test.util.AssertionErrors.fail(AssertionErrors.java:35)
at org.springframework.test.util.AssertionErrors.assertTrue(AssertionErrors.java:65)
at org.springframework.test.web.servlet.result.ContentResultMatchers$1.match(ContentResultMatchers.java:81)
at org.springframework.test.web.servlet.MockMvc$1.andExpect(MockMvc.java:171)
at org.wixanz.omniva.integration.FooControllerTest.notFoundFoo(FooControllerTest.java:87)
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.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:19)
... 28 more

NestedServletException wraps only the cause of the exception.
It is not your actual issue.
Its javadoc defines itself as :
Subclass of ServletException that properly handles a root cause in
terms of message and stacktrace, just like
NestedChecked/RuntimeException does.
Exceptions thrown in a rest controller have to be mapped to a http response. If you didn't it, Spring does that for you by throwing NestedServletException/NestedCheckedException according to the exception nature (checked or runtime).
A Java exception is not a http response.
You cannot let it be thrown as you did in a classic java code.
You have to convert it as something compatible with the http norms.
For Rest controllers you should use #ExceptionHandler and #ControllerAdvice.
#ControllerAdvice
public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
#ExceptionHandler(FooNotFoundException.class)
protected ResponseEntity<Object> handleFooNotFound(FooNotFoundException exception, WebRequest request) {
return handleExceptionInternal(exception, "Foo Not Found",
new HttpHeaders(), HttpStatus.NOT_FOUND, request);
}
}

How to test REST controller which use Pageable objec

I have a REST controller like above
#RequestMapping(value = "client", method = RequestMethod.GET, produces = "application/json")
public Page<ClientWithAddress> getAllClientsWithAddres(Pageable pageable){
return clientService.getAllClients(pageable);
}
When i try to run JUnit for it I got a NullPointerException on line with mockMvc.perform(get("/client")
#Test
public void Should_ReturnAllClients() throws Exception {
when(clientService.getAllClients(pageable)).thenReturn((page));
mockMvc.perform(get("/client"))
.andExpect(status().isOk())
Its probably, because i dont how o transfer Pageable object in test whean i call scope "/client" .
There is the stack
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:155)
at pl.xxxx.controller.ClientControllerUnitTest.Should_ReturnAllClients(ClientControllerUnitTest.java:133)
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.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:252)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
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$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$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 org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.getArgumentResolver(HandlerMethodArgumentResolverComposite.java:135)
at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.supportsParameter(HandlerMethodArgumentResolverComposite.java:106)
at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:156)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
... 38 more

the following one works for me,
mockMvc = MockMvcBuilders
.standaloneSetup(myController)
.setCustomArgumentResolvers(new PageableHandlerMethodArgumentResolver())
.build();
mockMvc.perform(MockMvcRequestBuilders
.get()

I'm not sure how you are instantiating your pageable object in your class here:
#Test
public void Should_ReturnAllClients() throws Exception {
when(clientService.getAllClients(pageable)).thenReturn((page));
mockMvc.perform(get("/client"))
.andExpect(status().isOk())
But I certainly doubt it will be the same pageable object created by the call to the controller. What you probably want to do is use a matcher in your stubbing instead:
when(clientService.getAllClients(Matchers.any(Pageable.class)).thenReturn((page));

If you are using #RunWith(SpringRunner.class) and #WebMvcTest(YourControllerUnderTest.class) then also add #EnableSpringDataWebSupport

Spring Controller Testing using Mockito , Null Pointer Exception

I am trying to test a Spring Controller using Mockito. I have mocked the object also used when() as per this question , but I am still facing the null pointer exception. Please suggest a way to solve this exception.
Github repository of this project
The particular line null pointer linked to is
modelMap.put("categories", simpleCategoryDAO.getAllCategories());
I have mocked simpleCategoryDAO and used when() to return a list for getAllCategories().
Test Method:
#RunWith(MockitoJUnitRunner.class)
public class CategoryControllerTest {
private MockMvc mockMvc;
#InjectMocks
private CategoryController categoryController;
#Mock
private SimpleCategoryDAO simpleCategoryDAO;
#Before
public void setup() {
categoryController = new CategoryController();
mockMvc = MockMvcBuilders.standaloneSetup(categoryController).build();
}
#Test
public void categories_ShouldRenderCategoriesView() throws Exception {
List<Category> ALL_CATEGORIES = Arrays.asList(
new Category(1,"Funny"),
new Category(2,"JoyFul")
);
Mockito.when(simpleCategoryDAO.getAllCategories()).thenReturn(ALL_CATEGORIES);
mockMvc.perform(get("/categories"))
//.andExpect((MockMvcResultMatchers.model()).attribute("categories",ALL_CATEGORIES));
.andExpect(MockMvcResultMatchers.view().name("categories"));
}
}
Code of controller
#Controller
public class CategoryController {
#Autowired
SimpleCategoryDAO simpleCategoryDAO;
#Autowired
SimpleGifDAO simpleGifDAO;
#RequestMapping("/categories")
public String getAllCategories(ModelMap modelMap) {
modelMap.put("categories", simpleCategoryDAO.getAllCategories());
return "categories";
}
#RequestMapping("/category/{categoryID}")
public String getGifsByCategoryID(#PathVariable int categoryID,ModelMap modelMap){
modelMap.put("gifs", simpleGifDAO.findGifsByCategoryID(categoryID));
modelMap.put("category",simpleCategoryDAO.getCategoryByID(categoryID));
return "category";
}
}
Exception:
java.lang.NullPointerException: null
at com.teja.controller.CategoryController.getAllCategories(CategoryController.java:23) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_73]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_73]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_73]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_73]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:776) ~[spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705) ~[spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) ~[spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) ~[spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967) [spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858) [spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) [tomcat-embed-core-8.0.23.jar:8.0.23]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843) [spring-webmvc-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65) [spring-test-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [tomcat-embed-core-8.0.23.jar:8.0.23]
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167) [spring-test-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) [spring-test-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:144) [spring-test-4.1.7.RELEASE.jar:4.1.7.RELEASE]
at CategoryControllerTest.categories_ShouldRenderCategoriesView(CategoryControllerTest.java:46) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_73]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_73]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_73]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_73]
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) [junit-4.12.jar:4.12]
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) [junit-4.12.jar:4.12]
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) [junit-4.12.jar:4.12]
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) [junit-4.12.jar:4.12]
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) [junit-4.12.jar:4.12]
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37) [mockito-core-1.10.19.jar:na]
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62) [mockito-core-1.10.19.jar:na]
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192) [.cp/:na]

The problem is on your test class Before method you are instantiating new controller
#Before
public void setup() {
categoryController = new CategoryController();
mockMvc = MockMvcBuilders.standaloneSetup(categoryController).build();
}
Here is how I do test for Controller
Controller Class :
#Controller
public class CategoryController {
private SimpleCategoryDAO simpleCategoryDAO;
private SimpleGifDAO simpleGifDAO;
#Autowired
public void setSimpleGifDAO(SimpleGifDAO simpleGifDAO) {
this.simpleGifDAO = simpleGifDAO;
}
#Autowired
public void setSimpleCategoryDAO(SimpleCategoryDAO simpleCategoryDAO) {
this.simpleCategoryDAO = simpleCategoryDAO;
}
#RequestMapping("/categories")
public String getAllCategories(ModelMap modelMap) {
modelMap.put("categories", simpleCategoryDAO.getAllCategories());
return "categories";
}
#RequestMapping("/category/{categoryID}")
public String getGifsByCategoryID(#PathVariable int categoryID, ModelMap modelMap) {
modelMap.put("gifs", simpleGifDAO.findGifsByCategoryID(categoryID));
modelMap.put("category", simpleCategoryDAO.getCategoryByID(categoryID));
return "category";
}
}
Notice I'm using setter injection here not field injection. You can also use constructor injection ( preferred way for me).
In you test class
#RunWith(MockitoJUnitRunner.class)
public class CategoryControllerTest {
private MockMvc mockMvc;
#Mock
private SimpleCategoryDAO simpleCategoryDAO;
#Before
public void setup() {
final CategoryController categoryController = new CategoryController();
//notice here I'm setting the mocked dao here
// if you didn't use #RunWith(MockitoJUnitRunner.class)
// you can do: simpleCategoryDAO = Mockito.mock(SimpleCategoryDAO.class);
categoryController.setSimpleCategoryDAO(simpleCategoryDAO);
mockMvc = MockMvcBuilders.standaloneSetup(categoryController).build();
}
#Test
public void categories_ShouldRenderCategoriesView() throws Exception {
List<Category> ALL_CATEGORIES = Arrays.asList(
new Category(1, "Funny"),
new Category(2, "JoyFul")
);
Mockito.when(simpleCategoryDAO.getAllCategories()).thenReturn(ALL_CATEGORIES);
mockMvc.perform(get("/categories"))
//.andExpect((MockMvcResultMatchers.model()).attribute("categories",ALL_CATEGORIES));
.andExpect(MockMvcResultMatchers.view().name("categories"));
}
}
Take a look at Before method on test. I'm setting the mocked DAO on the new instance of controller that I've created and then I'm creating the MockMvc using same instance of controller.

I had some issues with the provided solution so I thought I'd share how I solved it. My issue was that when the controller called a method on the DAO it was throwing NullPointerException, because I didn't want to use setter injection to provide the mocked DAO to the controller (I refused to create a setter method in the DAO just to be able to test everything).
Basically for the OP it would require:
NOT instantiating the controller in the setup() method (like Aman pointed out)
Declaring the DAO with the #Mock annotation before the controller declaration.
Like so:
#RunWith(MockitoJUnitRunner.class)
public class CategoryControllerTest {
private MockMvc mockMvc;
#Mock
private SimpleCategoryDAO simpleCategoryDAO;
#InjectMocks
private CategoryController categoryController;
#Before
public void setup() {
mockMvc = MockMvcBuilders.standaloneSetup(categoryController).build();
}
#Test
public void categories_ShouldRenderCategoriesView() throws Exception {
List<Category> ALL_CATEGORIES = Arrays.asList(
new Category(1,"Funny"),
new Category(2,"JoyFul")
);
Mockito.when(simpleCategoryDAO.getAllCategories()).thenReturn(ALL_CATEGORIES);
mockMvc.perform(get("/categories"))
//.andExpect((MockMvcResultMatchers.model()).attribute("categories",ALL_CATEGORIES));
.andExpect(MockMvcResultMatchers.view().name("categories"));
}
}