How to write JUnit Test case - junit

Question

I am learning Junit testing on spring boot Application. my account controller method is depend on service class method. For that I used Mockito. I tried simple But here I am not getting how to write test case for following method? How I can use mockito.
can any one please help me for writing this test case?
AccountController
#RestController
#RequestMapping("/spacestudy/$ {InstituteIdentifier}/admin/account")
public class AccountController {
#Autowired
AccountService accService;
#GetMapping("/findAccountData")
public ResponseEntity<List<Tuple>> populateGridViews(#RequestParam(value="sClientAcctId",required=false) String sClientAcctId,
#RequestParam(value="sAcctDesc",required=false) String sAcctDesc,
#RequestParam(value="sInvestigatorName",required=false)String sInvestigatorName,
#RequestParam(value="sClientDeptId",required=false) String sClientDeptId) throws Exception {
return ResponseEntity.ok(accService.populateGridViews(sClientAcctId, sAcctDesc,sInvestigatorName,sClientDeptId));
}
}
AccountService
public List<Tuple> populateGridViews(String sClientAcctId, String sAcctDesc, String sInvestigatorName,
String sClientDeptId)throws Exception{
QAccount account = QAccount.account;
QDepartment department = QDepartment.department;
QAccountCPCMapping accountCPCMapping = QAccountCPCMapping.accountCPCMapping;
QInvestigator investigator = QInvestigator.investigator;
JPAQuery<Tuple> query = new JPAQuery<Tuple>(em);
query.select(Projections.bean(Account.class, account.sClientAcctId, account.sAcctDesc, account.sLocation,
Projections.bean(Department.class, department.sDeptName, department.sClientDeptId).as("department"),
Projections.bean(Investigator.class, investigator.sInvestigatorName).as("investigator"),
Projections.bean(AccountCPCMapping.class, accountCPCMapping.sCCPCode).as("accountCPC"))).from(account)
.innerJoin(account.department, department).innerJoin(account.accountCPC, accountCPCMapping)
.innerJoin(account.investigator, investigator);
if (StringUtils.isNotEmpty(sClientAcctId)) {
query.where(account.sClientAcctId.equalsIgnoreCase(sClientAcctId));
}
// code.......
return query.fetch();
}
AccountControllerTest
#RunWith(SpringRunner.class)
public class TestAccountController {
private MockMvc mockMvc;
#Mock
private AccountService accountService;
#InjectMocks
private AccountController accountController;
#Before
public void setup() {
mockMvc = MockMvcBuilders.standaloneSetup(accountController).build();
}
#Test
public void populateGridViewsTest() throws Exception {
//????
//????
}
}

Answer 1

It will be something like this:
#RunWith(SpringRunner.class)
public class TestAccountController {
private MockMvc mockMvc;
#Mock
private AccountService accountService;
#InjectMocks
private AccountController accountController;
#Before
public void setup() {
mockMvc = MockMvcBuilders.standaloneSetup(accountController).build();
}
#Test
public void populateGridViewsTest() throws Exception {
when(accountService.populateGridViews("foo","bar")).thenReturn(Arrays.asList(new Tuple("bazz"));
mockMvc.perform(get("/spacestudy/STACKOVERFLOW/admin/account/foo/bar"))
.andExpect(status().isOk())
.andExpect(jsonPath("someField").value("bazz"));
}
}
So basically you are replacing your service with mock and saying what it should return. In your particular case I don't see any reasons for unit testing this class, since it doesn't have any logic inside. But if you would have something like:
#GetMapping("/findAccountData")
public ResponseEntity<List<Tuple>> populateGridViews(...) throws Exception {
List<Tuple> result = accService.populateGridViews(...);
if(result==null){
return ResponseEntity.notFound();
}
return ResponseEntity.ok(result);
}
Then it would make more sense to test this class e.g.
1st test - mock your accService to return null and verify that response status is 404
2nd test - mock your accService to return not null and verify that response status is 200