Make exponential histogram aggregation tests check feature flag (elastic#136672)

Author: JonasKunz

x-pack/plugin/mapper-exponential-histogram/src/test/java/org/elasticsearch/xpack/exponentialhistogram/aggregations/metrics/ExponentialHistogramAggregatorTestCase.java

@@ -16,15 +16,23 @@
 import org.elasticsearch.xpack.exponentialhistogram.ExponentialHistogramFieldMapper;
 import org.elasticsearch.xpack.exponentialhistogram.ExponentialHistogramMapperPlugin;
 import org.elasticsearch.xpack.exponentialhistogram.IndexWithCount;
+import org.junit.Before;
 
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
+import static org.elasticsearch.xpack.exponentialhistogram.ExponentialHistogramFieldMapper.EXPONENTIAL_HISTOGRAM_FEATURE;
+
 public abstract class ExponentialHistogramAggregatorTestCase extends AggregatorTestCase {
 
+    @Before
+    public void setup() {
+        assumeTrue("Only when exponential_histogram feature flag is enabled", EXPONENTIAL_HISTOGRAM_FEATURE.isEnabled());
+    }
+
     @Override
     protected List<SearchPlugin> getSearchPlugins() {
         return List.of(new ExponentialHistogramMapperPlugin());