java - 尝试模拟 Elastic Search 的 RestHighLevelClient 时出现 NullPointerException 问题

Question

在单元测试期间，我在尝试测试和模拟类RestHighLevelClient 内部时遇到 NullPointerException ElasticClient：

@Configuration
@NoArgsConstructor
public class ElasticClient{

   @Setter
   private RestHighLevelClient restHighLevelClient;

    @PostConstruct
    public void buildRestHighLevelClient(){

        RestClientBuilder restClientBuilder = RestClient.builder(new HttpHost(
                "127.0.0.1",
                9200, "http")
        );

        restClientBuilder.setRequestConfigCallback(
                requestConfigBuilder ->
                        requestConfigBuilder
                                .setConnectTimeout(500000)
                                .setSocketTimeout(600000)
                                .setConnectionRequestTimeout(0)
        )
                .setHttpClientConfigCallback(
                        httpClientBuilder ->
                                httpClientBuilder
                                        .setMaxConnPerRoute(2048)
                );

        restHighLevelClient = new RestHighLevelClient(restClientBuilder);
    }

   public boolean isReachable(){
     return restHighLevelClient.ping(RequestOptions.DEFAULT);
   }

}

和测试类：

@RunWith(MockitoJUnitRunner.class)
@SpringBootTest
public class ElasticClientTest{

@Mock
private RestHighLevelClient restHighLevelClient;


ElasticClient elasticClient;

@Before
public void init(){

    elasticClient = new ElasticClient();
    elasticClient.setRestHighLevelClient(restHighLevelClient);

}

NullPointerException 来自这里：

    @Test
    public void whenElasticIsPingable_thenReturnTrue() throws IOException{

           when(restHighLevelClient.ping(RequestOptions.DEFAULT)).thenReturn(true);
           Assertions.assertThat(elasticClient.isReachable()).isTrue();
    }

这是堆栈跟踪：

java.lang.NullPointerException
at org.elasticsearch.client.RestHighLevelClient.internalPerformRequest(RestHighLevelClient.java:1764)
at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:1734)
at org.elasticsearch.client.RestHighLevelClient.ping(RestHighLevelClient.java:694)
at com.example.ElasticClientTest.whenElasticIsPingable_thenReturnTrue(ElasticClientTest.java:44)

Answer 1

问题源于无法定期模拟 as中的ping方法。RestHighLevelClientfinal

所以，我使用了这个关于PowerMock的例子的帮助

在最终结果中：

@RunWith(PowerMockRunner.class)
@PrepareForTest(RestHighLevelClient.class)
public class ElasticClientTest{

ElasticClient elasticClient;

RestHighLevelClient restHighLevelClient;

@Before
public void init(){

    restHighLevelClient = mock(RestHighLevelClient.class);

    elasticClient = new ElasticClient();
    elasticClient.setRestHighLevelClient(restHighLevelClient);

}


@Test
public void whenElasticIsPingable_thenReturnTrue() throws IOException{

    when(restHighLevelClient.ping(RequestOptions.DEFAULT)).thenReturn(true);

    Assertions.assertThat(elasticClient.isReachable()).isTrue();
}

Answer 2

尝试：

when(restHighLevelClient.ping(eq(RequestOptions.DEFAULT))).thenReturn(true);

Answer 3

您需要通过以下步骤为模拟最终对象添加模拟扩展：

1. 在测试资源文件夹中创建一个名为“mockito-extensions”的文件夹。
2. 在文件夹中添加一个名为“org.mockito.plugins.MockMaker”的文件。
3. 在那个文件中，写“mock-maker-inline”