Fixed test file

Signed-off-by: Somesh Gupta <someshgupta987@gmail.com>

server/src/test/java/org/opensearch/action/admin/indices/shards/CatShardsResponseTests.java

@@ -4,36 +4,23 @@
 import org.opensearch.action.admin.cluster.state.ClusterStateResponse;
 import org.opensearch.action.admin.indices.stats.IndicesStatsResponse;
 import org.opensearch.cluster.ClusterName;
-import org.junit.Before;
-import org.junit.Test;
+import org.opensearch.test.OpenSearchTestCase;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNull;
 
-public class CatShardsResponseTests {
+public class CatShardsResponseTests extends OpenSearchTestCase {
 
-    private CatShardsResponse catShardsResponse;
+    private final CatShardsResponse catShardsResponse = new CatShardsResponse();
 
-    @Before
-    public void setUp() {
-        catShardsResponse = new CatShardsResponse();
-    }
-
-    @Test
     public void testGetAndSetClusterStateResponse() {
-        assertNull(catShardsResponse.getClusterStateResponse());
-
         ClusterName clusterName = new ClusterName("1");
         ClusterStateResponse clusterStateResponse = new ClusterStateResponse(clusterName, null, false);
         catShardsResponse.setClusterStateResponse(clusterStateResponse);
 
         assertEquals(clusterStateResponse, catShardsResponse.getClusterStateResponse());
     }
 
-    @Test
     public void testGetAndSetIndicesStatsResponse() {
-        assertNull(catShardsResponse.getIndicesStatsResponse());
-
         final IndicesStatsResponse indicesStatsResponse = new IndicesStatsResponse(null, 0, 0, 0, null);
         catShardsResponse.setIndicesStatsResponse(indicesStatsResponse);