Writing JUnit tests for Spring Validator implementation

Question

I\'m using Spring Validator implementations to validate my object and I would like to know how do you write a unit test for a validator like this one:

public         


        

Answer 1

Here is the code that shows how to unit test for validation:

1) The main Validator class for which one needs to write unit test:

public class AddAccountValidator implements Validator {

    private static Logger LOGGER = Logger.getLogger(AddAccountValidator.class);

    public boolean supports(Class clazz) {
        return AddAccountForm.class.equals(clazz);
    }

    public void validate(Object command, Errors errors) {
        AddAccountForm form = (AddAccountForm) command;
        validateFields(form, errors);
    }

    protected void validateFields(AddAccountForm form, Errors errors) {
        if (!StringUtils.isBlank(form.getAccountname()) && form.getAccountname().length()>20){
            LOGGER.info("Account Name is too long");
            ValidationUtils.rejectValue(errors, "accountName", ValidationUtils.TOOLONG_VALIDATION);
        }
    }
}

2) Utility class supporting 1)

public class ValidationUtils {
    public static final String TOOLONG_VALIDATION = "toolong";

    public static void rejectValue(Errors errors, String fieldName, String value) {
        if (errors.getFieldErrorCount(fieldName) == 0){
            errors.rejectValue(fieldName, value);
        }
    }
}

3) Here is the unit test:

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;

import org.junit.Test;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.Errors;

import com.bos.web.forms.AddAccountForm;

public class AddAccountValidatorTest {

    @Test
    public void validateFieldsTest_when_too_long() {
        // given
        AddAccountValidator addAccountValidator = new AddAccountValidator();
        AddAccountForm form = new AddAccountForm();
        form.setAccountName(
                "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1");

        Errors errors = new BeanPropertyBindingResult(form, "");

        // when
        addAccountValidator.validateFields(form, errors);

        // then
        assertEquals(
                "Field error in object '' on field 'accountName': rejected value [aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1]; codes [toolong.accountName,toolong.java.lang.String,toolong]; arguments []; default message [null]",
                errors.getFieldError("accountName").toString());
    }

    @Test
    public void validateFieldsTest_when_fine() {
        // given
        AddAccountValidator addAccountValidator = new AddAccountValidator();
        AddAccountForm form = new AddAccountForm();
        form.setAccountName("aaa1");
        Errors errors = new BeanPropertyBindingResult(form, "");

        // when
        addAccountValidator.validateFields(form, errors);

        // then
        assertNull(errors.getFieldError("accountName"));
    }

}

Answer 2

It is a really straight forward test without any mock. (just the error-object creation is a bit tricky)

@Test
public void testValidationWithValidAddress() {
    AdressValidator addressValidator = new AddressValidator();
    CustomValidator validatorUnderTest = new CustomValidator(adressValidator);

    Address validAddress = new Address();
    validAddress.set... everything to make it valid

    Errors errors = new BeanPropertyBindingResult(validAddress, "validAddress");
    validatorUnderTest.validate(validAddress, errors);

    assertFalse(errors.hasErrors()); 
}


@Test
public void testValidationWithEmptyFirstNameAddress() {
    AdressValidator addressValidator = new AddressValidator();
    CustomValidator validatorUnderTest = new CustomValidator(adressValidator);

    Address validAddress = new Address();
    invalidAddress.setFirstName("")
    invalidAddress.set... everything to make it valid exept the first name

    Errors errors = new BeanPropertyBindingResult(invalidAddress, "invalidAddress");
    validatorUnderTest.validate(invalidAddress, errors);

    assertTrue(errors.hasErrors());
    assertNotNull(errors.getFieldError("firstName"));
}

BTW: if you really want to make it more complicate and make it complicate by a mock, then have a look at this Blog, they use a two mocks, one for the object to test (ok, this is useful if you can not create one), and a second for the Error object (I think this is more complicated the it must be.)