### Question:
ConstraintHelper { public boolean isConstraintAnnotation(Annotation annotation) { Constraint constraint = annotation.annotationType() .getAnnotation( Constraint.class ); if ( constraint == null ) { return false; } try { ReflectionHelper.getAnnotationParameter( annotation, "message", String.class ); } catch ( Exception e ) { String msg = annotation.annotationType().getName() + " contains Constraint annotation, but does " + "not contain a message parameter. Annotation is getting ignored."; log.warn( msg ); return false; } try { ReflectionHelper.getAnnotationParameter( annotation, "groups", Class[].class ); } catch ( Exception e ) { String msg = annotation.annotationType().getName() + " contains Constraint annotation, but does " + "not contain a groups parameter. Annotation is getting ignored."; log.warn( msg ); return false; } Method[] methods = annotation.getClass().getMethods(); for ( Method m : methods ) { if ( m.getName().startsWith( "valid" ) ) { String msg = "Parameters starting with 'valid' are not allowed in a constraint."; log.warn( msg ); return false; } } return true; } ConstraintHelper(); List<Class<? extends ConstraintValidator<? extends Annotation, ?>>> getBuiltInConstraints(Class<? extends Annotation> annotationType); boolean isBuiltinConstraint(Class<? extends Annotation> annotationType); boolean isMultiValueConstraint(Annotation annotation); List<Annotation> getMultiValueConstraints(A annotation); boolean isConstraintAnnotation(Annotation annotation); List<Class<? extends ConstraintValidator<? extends Annotation, ?>>> getConstraintValidatorDefinition(Class<? extends Annotation> annotationClass); void addConstraintValidatorDefinition(Class<A> annotationClass, List<Class<? extends ConstraintValidator<? extends Annotation, ?>>> definitionClasses); boolean containsConstraintValidatorDefinition(Class<? extends Annotation> annotationClass);  }### Answer:
@Test public void testConstraintWithNoMessage() { Annotation annotation = new NoGroups() { public String message() { return ""; } public Class<? extends Annotation> annotationType() { return this.getClass(); } }; assertFalse( constraintHelper.isConstraintAnnotation( annotation ), "The constraint annotation should not be valid" ); }
@Test public void testConstraintWithNoGroups() { Annotation annotation = new NoMessage() { public Class<?>[] groups() { return null; } public Class<? extends Annotation> annotationType() { return this.getClass(); } }; assertFalse( constraintHelper.isConstraintAnnotation( annotation ), "The constraint annotation should not be valid" ); }
@Test public void testConstraintWithValidInPropertyName() { Annotation annotation = new ValidProperty() { public String message() { return null; } public Class<?>[] groups() { return null; } public int validLength() { return 0; } public Class<? extends Annotation> annotationType() { return this.getClass(); } }; assertFalse( constraintHelper.isConstraintAnnotation( annotation ), "The constraint annotation should not be valid" ); }