模拟时junit中的错误

这是我的工作代码：

import static org.junit.Assert.assertEquals;import java.util.HashMap;import org.junit.Before;import org.junit.Test;import org.junit.runner.RunWith;import org.mockito.InjectMocks;import org.mockito.Mockito;import org.powermock.api.mockito.PowerMockito;import org.powermock.core.classloader.annotations.PrepareForTest;import org.powermock.modules.junit4.PowerMockRunner;@RunWith(PowerMockRunner.class)@PrepareForTest(CollectionUtil.class)public class TestHarnesTest {    @InjectMocks    TestHarnes w_res = new TestHarnes();    @Before    public void before() {        PowerMockito.mockStatic(CollectionUtil.class);    }    @Test    public void test_removeHashedSettings() throws Exception {        HashMap<String, String> w_abc = new HashMap<String, String>();        w_abc.put("abc", "89");        // CollectionUtil mock = org.mockito.Mockito.mock(CollectionUtil.class);        // PowerMockito.mockStatic(CollectionUtil.class,w_abc);        PowerMockito.when(CollectionUtil.createHashMap(Mockito.eq("abc:89"), Mockito.eq(":"))).thenReturn(w_abc);        assertEquals("abc:89:", TestHarnes.removeHashedSettings("1", "abc:89", ":"));    }}

和TestHarnes类

public class TestHarnes {    public static String removeHashedSettings(final String key, final String a_settings, final String deilimiter) throws Exception {        if (!(key != null && key.trim().length() > 0)) { return a_settings;        }        if (!(a_settings != null && a_settings.trim().length() > 0)) { return a_settings;        }        HashMap hSettings = CollectionUtil.createHashMap(a_settings, deilimiter);        hSettings.remove(key);        return getSettingFromHash(hSettings, deilimiter);    }    private static String getSettingFromHash(final HashMap hSettings, final String deilimiter) {        return "";    }}