import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.annotation.PostConstruct;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.equalTo;

enum SomeSingletonService {
    INSTANCE;

    public int num;

    private SomeSingletonService() {
        num = 0;
    }
}

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:/context.xml"})
public class Example {

    private SomeSingletonService s = SomeSingletonService.INSTANCE;

    @PostConstruct
    public void init() {
        ++s.num;
    }

    @Test
    public void t1() {
        assertThat(s.num, equalTo(1));
    }

    @Test
    public void t2() {
        assertThat(s.num, equalTo(2));
    }

    @Test
    public void t3() {
        assertThat(s.num, equalTo(3));
    }

}