JSR 303 bean validation unit testing with Mockito and Autowiring

junit4, mockito, unit-testing, validation

Solution

To achieve this I created custom ConstraintValidatorFactory to provide my custom ConstraintValidator.

Assume we have the following:

- SomeValidation - Bean Validation constraint annotation

- SomeValidationValidator - Bean Validation constraint validator with @Autowired dependencies. It contains two constructors: default and the one that takes dependencies

Now you can create a test SomeValidationValidatorTest that implements ConstraintValidatorFactory and is run with MockitoJUnitRunner.class:

@RunWith(MockitoJUnitRunner.class)
public class SomeValidationValidatorTest implements ConstraintValidatorFactory {
    @Mock
    private MyDependency myDependencyMock;
}

You must implement getInstance method from ConstraintValidatorFactory:

@Override
public <T extends ConstraintValidator<?, ?>> T getInstance(Class<T> key) {
    if (key == SomeValidationValidator.class) {
        return (T) new SomeValidationValidator(myDependencyMock);
    }
    throw new IllegalArgumentException("expecting SomeValidationValidator!");
}

Having this you can configure the Validator:

@Before
public void setUp() throws Exception {

    // see https://docs.jboss.org/hibernate/validator/5.2/reference/en-US/html/chapter-bootstrapping.html#_constraintvalidatorfactory
    Configuration<?> config = Validation.byDefaultProvider().configure();
    config.constraintValidatorFactory(this);

    ValidatorFactory factory = config.buildValidatorFactory();

    validator = factory.getValidator();
}

In the end create some test:

@Test
public void someTest1() {
    // arrange
    Bean bean = new Bean();
    Mockito.when(myDependencyMock.isValid(null)).thenReturn(true);
    // act
    Set<ConstraintViolation<Bean>> constraintViolations = validator.validate(bean);
    // assert
    Assert.assertTrue(constraintViolations.isEmpty());
    Mockito.verify(myDependencyMock).isValid(null);
}

The above solution is not perfect but I assume it gives you the idea of using custom ConstraintValidatorFactory to solve the problem.

Problem

I want to junit test my validator class but my validator class has @autowired service classes. How do I inject these dependencies using Mocikto? I am going to call the validator using below line of code. ``` Set<ConstraintViolation<MyDomainPOJOObject>> constraintViolationsFromJavaRules = validator.validate(myDomainPOJOObject, Default.class); ``` Problem is I am not instantiating validator class myself. It's the JSR 303 framework which truely calls the validator's isValid method(). Another thing is I don't want to use spring Autowiring and use the `@Mock and @InjectMock` annotations. Any examples or ideas? I was able to get it working by having below line of code ``` @Override public <T extends ConstraintValidator<?, ?>> T getInstance(Class<T> key) { if (key == com.nitin.validation.UpperCaseValidator.class) { return (T)upperCasevalidator; } //throw new IllegalArgumentException("expecting SomeValidationValidator!"); return new ConstraintValidatorFactoryImpl().getInstance(key); } ```

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