如何模拟下面方法的实现，我无法模拟BulkResponse。

public void aferBulk(long id, BulkRequest bulkRequest, BulkResponse bulkResponse) {
    if(bulkResponse.hasFailures()) {
        logFailedResponses(bulkResponse);
    }else {
        //some action
    }
}

private void logFailedBulkItems(BulkResponse bulkResponse) {
     for (BulkItemResponse bulkItemResponse : bulkResponse) {
            if (bulkItemResponse.isFailed()) {
                BulkItemResponse.Failure failure = bulkItemResponse.getFailure();
                LOGGER.error("ES索引失败: {}", failure.getMessage());
            }
        }
}
}

我已经尝试过了，但是，我无法嘲笑下面的行

for (BulkItemResponse bulkItemResponse : bulkResponse)

模拟代码：

public void TestMethod(){
    BulkResponse bulkResponse = mock(BulkResponse.class);
    when(bulkResponse.hasFailures()).thenReturn(true);
    when(response.hasFailures()).thenReturn(responseHasFailures);
    BulkItemResponse item1 = mock(BulkItemResponse.class);
    BulkItemResponse item2 = mock(BulkItemResponse.class);
    when(item1.getItemId()).thenReturn(1);
    when(item1.isFailed()).thenReturn(true);
    BulkItemResponse.Failure failure = mock(BulkItemResponse.Failure.class);
    when(failure.getMessage()).thenReturn("Bad message");
    when(item1.getFailure()).thenReturn(failure);
    when(item2.getItemId()).thenReturn(2);
    when(item2.isFailed()).thenReturn(false);
    when(response.getItems()).thenReturn(new BulkItemResponse[]{item1, item2});
}