问简单的Mockito验证JUnit中的工作而不是Spock？

import org.junit.Test;

import java.util.List;

import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;

public class SimpleJunitTest
{
    @Test
    public void basicMockTest()
    {
        List mockedList = mock(List.class);

        //using mock object
        mockedList.add("one");
        mockedList.clear();

        //verification
        verify(mockedList).add("one");
        verify(mockedList).clear();
    }
}

import static org.mockito.Mockito.mock
import static org.mockito.Mockito.verify


class SimpleSpockTest extends spock.lang.Specification
{
    def "Basic Mock Test"()
    {
        given:
            //mock creation
            List mockedList = mock(List.class);

        when:
            //using mock object
            mockedList.add("one");
            mockedList.clear();

        then:
            //verification
            verify(mockedList).add("one");
            verify(mockedList).clear();
    }

}

Condition not satisfied:

verify(mockedList).add("one")
|      |           |
|      |           false
|      $java.util.List$$EnhancerByMockitoWithCGLIB$$172e393a@613043d2 (renderer threw    
NullPointerException)
$java.util.List$$EnhancerByMockitoWithCGLIB$$172e393a@613043d2 (renderer threw 
NullPointerException)

at SimpleSpockTest.Basic Mock Test(SimpleSpockTest.groovy:25)