spring crud repo not reading data inserted by test case - spring-boot

Question

I am trying to write my first integration test with spring boot application. So to write proper test cases I am using #Transactional provided by spring so that state of my in memory data base remains same before and after execution the test.
Thing is #Transactional is working as expected my test execution starts it inserts some data for testing into db and when execution finish it rollbacks the changes done by it but the problem is when the test execution goes to the code I am testing it tries to fetch data persisted by test but does not find any data there. I've shared my code for better understanding.
#RunWith(SpringRunner.class)
#SpringBootTest
#Transactional
public class MyFirstControllerTest {
#Autowired
private TestRestTemplate restTemplate;
#Autowired
private MyFirstRepository myFirstRepo;
#Test
public void testMethod() {
//insert some data.
Dummy data = new DummyData();
myFirstRepo.save(data);
//hits the rest route to get data.
ResponseEntity<String> response =
this.restTemplate.getForEntity("/dummys", String.class); // did not find any data in db.
myFirstRepo.findAll(); //working - fetched the data inserted in test.
}
}
Below is my controller.
#Controller
#Validated
public class MyFirstController {
#Autowired
private MyFirstRepository myFirstRepo;
#GetMapping("/dummys")
public ResponseEntity<List<DummyDataDto>> getDummyData() {
List<DummyData> data = myFirstRepo.findAll(); //does not finds any data
//convert list of dummy data to list of dummydata dto.
return new ResponseEntity<DummyDataDto>(List<DummyDataDto>, HttpStatus.OK);
}
}

Answer 1

This is occurring because of the isolation level of in memory database that you have been using. I assume that default isolation level of that database in Read Committed.
If you are using H2 then you may find details of isolation level here.
All you need to use Read Uncommited isolation level for integration test, if your business requirement says to do so.