DBOperationManagementTest.java

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import java.util.HashMap;
import java.util.Map;

import static junit.framework.Assert.assertEquals;
import static org.powermock.api.mockito.PowerMockito.when;

@RunWith(PowerMockRunner.class)
@PrepareForTest({Database.class, Document.class})
public class DBOperationManagementTest {

    private static final Map<String, Object> data = new HashMap<>();
    private static final String EXPECT_DOC_ID = "id-1";

    Database mockDatabase;

    Document mockDocument;

    @Before
    public void initMocks() throws CouchbaseLiteException {
        createMockObject();
    }

    @After
    public void tearDown() throws Exception {
        resetMockObject();
    }

    @Test
    public void test_createDoc(){
        String docId = DBOperationManagement.createDoc(mockDatabase, data);
        System.out.println(docId);

        assertEquals(EXPECT_DOC_ID, docId);
    }

    @Test
    public void test_deleteDoc() throws CouchbaseLiteException {
        boolean deleteResult = DBOperationManagement.deleteDoc(mockDatabase, "");
        assertEquals(true, deleteResult);

        Mockito.verify(mockDocument).delete();
    }


    private void createMockObject() throws CouchbaseLiteException {
        mockDatabase = PowerMockito.mock(Database.class);
        mockDocument = PowerMockito.mock(Document.class);

        when(mockDocument.getId()).thenReturn("id-1");
        when(mockDocument.putProperties(data)).thenReturn(null);
        when(mockDocument.isDeleted()).thenReturn(true);

        when(mockDatabase.createDocument()).thenReturn(mockDocument);
        when(mockDatabase.getDocument("")).thenReturn(mockDocument);
    }

    private void resetMockObject() {
        mockDatabase = null;
        mockDocument = null;
    }

}

Mockito and Powermock integration