Add unit tests for DateHistogramAggregator

Adds unit tests for the date histogram aggregator. Relates elastic#22278
tlrx · Jan 20, 2017 · e6584be · e6584be
1 parent 5d806bf
commit e6584be
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diff --git a/core/src/test/java/org/elasticsearch/search/aggregations/AggregatorTestCase.java b/core/src/test/java/org/elasticsearch/search/aggregations/AggregatorTestCase.java
@@ -172,10 +172,13 @@ protected <A extends InternalAggregation, C extends Aggregator> A searchAndReduc
                     aggs.add(a.buildAggregation(0L));
                 }
             }
-            @SuppressWarnings("unchecked")
-            A internalAgg = (A) aggs.get(0).doReduce(aggs,
-                new InternalAggregation.ReduceContext(root.context().bigArrays(), null));
-            return internalAgg;
+            if (aggs.isEmpty()) {
+                return null;
+            } else {
+                @SuppressWarnings("unchecked")
+                A internalAgg = (A) aggs.get(0).doReduce(aggs, new InternalAggregation.ReduceContext(root.context().bigArrays(), null));
+                return internalAgg;
+            }
         }
     }