单元测试数据库调用

Question

我有一个带有静态函数的类，执行数据库操作，例如保存，检索和删除。

我的数据库类：

public final class DbUtils {
    static {
        DB_USER = //get from secure server
        DB_PASSWORD = //get from secure server
    }

    private static Connection establishConnection() {
    }
    private static void closeConnection(Connection connection) {
    }
    public static boolean saveObject(final Object graph, final Object map) {
        Connection connection = establishConnection();
        try {
            byte[] bgraph = ConvertToByte(graph);
            byte[] bmap = ConvertToByte(map);
            statement = connection.prepareStatement("INSERT IGNORE INTO " + TABLE_NAME + " VALUES (?,?)");
            statement.setObject(1, graph);
            statement.setObject(2, map);
            statement.executeUpdate();
            //Close statement within try catch
        } catch(Exception e) { // also other exception
            //catch to catch all type of exception
        }
        closeConnection(connection);
        return true;
    }
    public static Map<String, Object> retrieveObject(final String key) {
        Connection connection = establishConnection();
        //read byte and convert to object
        closeConnection(connection);
        return map;
    }
    public static boolean deleteObject(final String key) {
        Connection connection = establishConnection();
        //delete all object except object with key
        closeConnection(connection);
        return (affectedRow >= 1);
    }
}

我写了一个单元测试来测试它，如下所示：

@RunWith(PowerMockRunner.class)
@PrepareForTest(DbUtils.class)
@SuppressStaticInitializationFor("DbUtils")
public class DbUtilsTest {
    @Mock
    Connection connection;
    @Mock
    ModuleDependencyGraph dependencyGraph;
    @Mock
    private Map<String , String> moduleSDF;
    @Test
    public void testSaveObject() throws Exception {
        PowerMockito.spy(DbUtils.class);
        PowerMockito.doReturn(connection).when(DbUtils.class, "establishConnection");
        Assert.assertTrue(DbUtils.saveObject(dependencyGraph, moduleSDF));
    }
}

当我尝试运行此单元测试时，我在statement = connection.prepareStatement行出现空指针错误，我认为这是意料之中的，因为我没有正确模拟连接。如何正确模拟连接？另外，我编写saveObject测试的方式是否正确？我是单元测试的新手，所以我不知道最佳实践以及如何涵盖所有情况。

Answer 1

@Mock
Statement statement;
doReturn(statement).when(connection).prepareStatement(anyString());
doNothing().when(statement).setObject(any(), any());
doNothing().when(statement).executeUpdate();

这是只使用Mockito。您也可以使用PowerMockito。它应该同样有效。