模拟不返回任何内容的casted对象时的ClassCastException

我试图模拟(使用mock I to)一个具有以下代码的方法:

Channel channel = session.openChannel("exec");
((ChannelExec)channel).setCommand(command);
channel.setInputStream(null);

((ChannelExec)channel).setCommand(command);

例外情况如下:

java.lang.ClassCastException: com.jcraft.jsch.Channel$$EnhancerByMockitoWithCGLIB$$15aeab7e cannot be cast to com.jcraft.jsch.ChannelExec

这是我的单元测试:

    @Test
public void testExecuteSSHCommand() throws JSchException, IOException {
    Channel channel = mock(Channel.class);
    ChannelExec channelExec = mock(ChannelExec.class);

    String command = "dummyCommand";
    String result = "the correct result";
    InputStream inputStream = new ByteArrayInputStream(result.getBytes(StandardCharsets.UTF_8));;

    when(channel.getInputStream()).thenReturn(inputStream);
    when(session.openChannel("exec")).thenReturn(channel);
    //when(channel.setCommand(command)).get();

    logger.info("Returning {}", sshClient.executeSSHCommand(session, command));
    assertEquals(result, sshClient.executeSSHCommand(session, command));
}