How to test my @NotEmpty with JUnit

We have to remove almost every framework used in the code. I started
with the @NotEmpty from Hibernate. It was the only class used from
Hibernate, so low hanging fruit we thought.

I wrote the following implementation:

import        java.lang.annotation.Documented;
import static java.lang.annotation.ElementType.FIELD;
import        java.lang.annotation.Retention;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import        java.lang.annotation.Target;

import        javax.validation.Constraint;
import        javax.validation.constraints.NotNull;
import        javax.validation.constraints.Size;
import        javax.validation.ReportAsSingleViolation;

@Constraint(validatedBy = {})
@Target({ FIELD })
@Size(min = 1)
public @interface NotEmpty {
    public abstract String message() default "Field has to be filled";

But it should be tested also of-course. So I wrote the following test:

import org.junit.Test;

class NotEmptyClass {
    String notEmpty;

    NotEmptyClass(String value) {
        notEmpty = value;

public class NotEmptyTest {
    public void firstTest() {
        new NotEmptyClass(null);

I would expect this test not to pass, but it does. So clearly I am
doing something wrong, but I have no idea what. (This is the first
time I really work with annotations.) I did some Googling but until
now to no avail. So if someone could point me to the right direction …

Source: java

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