How to unit test spring datetimeformat validation

ab91 :

I have a DTO class holding two date fields. Both are annotated with a @NotNull and @DateTimeFormat.

I'm doing TDD and I noticed my NotNull error message is returned successfully but when I pass in a date in my unit test it accepts pretty much anything even if it doesn't match my pattern.

Interestingly when I test in my thymeleaf form it works correctly, giving me back the error message I expect with a malformed date.

I'm assuming this is something to do with spring not applying the DateTimeFormat when I unit test just the DTO but then why would my not null work as expected?

I've provided the code for the DTO below

import org.springframework.format.annotation.DateTimeFormat;
import javax.validation.constraints.NotNull;
import java.util.Date;

public class HourTracker {
@NotNull(message = "start time cannot be null")
@DateTimeFormat(pattern = "hh:mma")
private Date startTime;
@NotNull(message = "end time cannot be null")
@DateTimeFormat(pattern = "hh:mma")
private Date endTime;

//getters and setters
}

Unit Test:

public class HourTrackerTest {
private static final String HOURS_INPUT_FORMAT = "hh:mma";
private Validator validator;
private HoursTracker tested;

@Before
public void setUp() throws Exception {
    tested = new HoursTracker();
    ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
    validator = factory.getValidator();
}

@Test
public void testValidTimeInputs() throws Exception {
    SimpleDateFormat timeFormatForDate = new SimpleDateFormat(HOURS_INPUT_FORMAT);
    Date validTimeInput = timeFormatForDate.parse("12:30pm");
    tested.setStartTime(validTimeInput);
    tested.setEndTime(validTimeInput);
    assertEquals("Start time was not correctly set", validTimeInput, tested.getStartTime());
    assertEquals("End time was not correctly set", validTimeInput, tested.getStartTime());
}

@Test
public void testNullStartTimeInputErrorMessage() throws Exception {
    tested.setStartTime(null);
    Set<ConstraintViolation<HoursTrackingForm>> violations = validator.validate(tested);
    assertFalse("No violation occurred, expected one", violations.isEmpty());
    assertEquals("Incorrect error message",
            "Please enter a valid time in AM or PM",
            violations.iterator().next().getMessage()
    );
}

@Test
public void testNullEndTimeInputErrorMessage() throws Exception {
    tested.setEndTime(null);
    Set<ConstraintViolation<HoursTrackingForm>> violations = validator.validate(tested);
    assertFalse("No violation occurred, expected one", violations.isEmpty());
    assertEquals("Incorrect error message",
            "Please enter a valid time in AM or PM",
            violations.iterator().next().getMessage()
    );
}

}

ab91 :

Simple answer, you cannot test a Spring constraint outside of the spring container. I was attempting to test in the way I would test my javax validations