Junit 测试用例（NextDate）,该如何处理

public class Date {    private Day d;    private Month m;    private Year y;    public Date(int pMonth, int pDay, int pYear) {        y = new Year(pYear);        m = new Month(pMonth, y);        d = new Day(pDay, m);    }    public void increment() {        if (!d.increment()) {            if (!m.increment()) {                y.increment();                m.setMonth(1, y);            }            d.setDay(1, m);        }    }    public void printDate() {        System.out.println(m.getMonth() + "/" + d.getDay() + "/" + y.getYear());    }    public String getDate(){        return m.getMonth() + "/" + d.getDay() + "/" + y.getYear();    }}

import static org.junit.Assert.assertEquals;import java.util.Arrays;import java.util.Collection;import nextdate.Date;import org.junit.Test;import org.junit.runner.JUnitCore;import org.junit.runner.RunWith;import org.junit.runners.Parameterized;import org.junit.runners.Parameterized.Parameters;@RunWith(Parameterized.class)public class DateTest {        private static String expected;    private static int target;        /**     * 构造函数     * @param expected     *            期望的测试结果，对应参数集中的第一个参数     * @param target     *            测试数据，对应参数集中的第二个参数     */    public DateTest(String expected, int target) {        this.expected = expected;        this.target = target;    }        @Parameters    public  static Collection dates() {           //问题就在这个静态方法，里边调用外部类，去static        Date date0 = new Date(6, 15, 2000);   //又不行，该怎么修改？？？        Date date1 = new Date(2, 29, 2000);        Date date2 = new Date(2, 28, 2001);        Date date3 = new Date(3, 30, 2000);        Date date4 = new Date(4, 30, 2000);        date0.increment();        date1.increment();        date2.increment();        date3.increment();        date4.increment();        return Arrays.asList(new Object[][] {                 { "6/16/2000", date0.getDate()},                 { "3/1/2000",  date1.getDate() },                 { "2/29/2000", date2.getDate() },                 { "3/31/2000", date3.getDate() },                 { "5/1/2000",  date4.getDate()},                    });    }    @Test    public void increment() {        assertEquals(expected,target);    }    public static void main(String[] args) {        JUnitCore.main(new String[] { "DateTest" });    }}