Tests: Add unit test for InternalChildren (#23261)

Relates to #22278

core/src/main/java/org/elasticsearch/search/aggregations/bucket/InternalSingleBucketAggregation.java

@@ -30,6 +30,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 /**
  * A base class for all the single bucket aggregations.
@@ -80,7 +81,7 @@ public InternalAggregations getAggregations() {
     /**
      * Create a new copy of this {@link Aggregation} with the same settings as
      * this {@link Aggregation} and contains the provided sub-aggregations.
-     * 
+     *
      * @param subAggregations
      *            the buckets to use in the new {@link Aggregation}
      * @return the new {@link Aggregation}
@@ -133,4 +134,16 @@ public XContentBuilder doXContentBody(XContentBuilder builder, Params params) th
         aggregations.toXContentInternal(builder, params);
         return builder;
     }
+
+    @Override
+    protected boolean doEquals(Object obj) {
+        InternalSingleBucketAggregation other = (InternalSingleBucketAggregation) obj;
+        return Objects.equals(docCount, other.docCount) &&
+                Objects.equals(aggregations, other.aggregations);
+    }
+
+    @Override
+    protected int doHashCode() {
+        return Objects.hash(docCount, aggregations);
+    }
 }

core/src/test/java/org/elasticsearch/search/aggregations/bucket/children/InternalChildrenTests.java

@@ -0,0 +1,66 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.search.aggregations.bucket.children;
+
+import org.elasticsearch.common.io.stream.Writeable.Reader;
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.InternalAggregation;
+import org.elasticsearch.search.aggregations.InternalAggregationTestCase;
+import org.elasticsearch.search.aggregations.InternalAggregations;
+import org.elasticsearch.search.aggregations.metrics.max.InternalMax;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class InternalChildrenTests extends InternalAggregationTestCase<InternalChildren> {
+
+    @Override
+    protected InternalChildren createTestInstance(String name, List<PipelineAggregator> pipelineAggregators,
+            Map<String, Object> metaData) {
+        // we shouldn't use the full long range here since we sum doc count on reduce, and don't want to overflow the long range there
+        long docCount = randomIntBetween(0, Integer.MAX_VALUE);
+        int numAggregations = randomIntBetween(0, 20);
+        List<InternalAggregation> aggs = new ArrayList<>(numAggregations);
+        for (int i = 0; i < numAggregations; i++) {
+            aggs.add(new InternalMax(randomAsciiOfLength(5), randomDouble(),
+                    randomFrom(DocValueFormat.BOOLEAN, DocValueFormat.GEOHASH, DocValueFormat.IP, DocValueFormat.RAW), pipelineAggregators,
+                    metaData));
+        }
+        // don't randomize the name parameter, since InternalSingleBucketAggregation#doReduce asserts its the same for all reduced aggs
+        return new InternalChildren("childAgg", docCount, new InternalAggregations(aggs), pipelineAggregators, metaData);
+    }
+
+    @Override
+    protected void assertReduced(InternalChildren reduced, List<InternalChildren> inputs) {
+        long expectedDocCount = 0;
+        for (Children input : inputs) {
+            expectedDocCount += input.getDocCount();
+        }
+        assertEquals(expectedDocCount, reduced.getDocCount());
+    }
+
+    @Override
+    protected Reader<InternalChildren> instanceReader() {
+        return InternalChildren::new;
+    }
+
+}