Add unit tests for ParentToChildAggregator (#23305)

Adds unit tests for the `children` aggregation.
This change also add the ability to mock Mapperservice in subtests of
AggregatorTestCase.

core/src/test/java/org/elasticsearch/search/aggregations/AggregatorTestCase.java

@@ -43,6 +43,7 @@ import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
+import org.elasticsearch.indices.fielddata.cache.IndicesFieldDataCache;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.subphase.DocValueFieldsFetchSubPhase;
 import org.elasticsearch.search.fetch.subphase.FetchSourceSubPhase;
@@ -50,6 +51,7 @@ import org.elasticsearch.search.internal.ContextIndexSearcher;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.search.lookup.SearchLookup;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.test.IndexSettingsModule;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -112,11 +114,15 @@ public abstract class AggregatorTestCase extends ESTestCase {
         }).when(searchContext).addReleasable(anyObject(), anyObject());
 
         // TODO: now just needed for top_hits, this will need to be revised for other agg unit tests:
-        MapperService mapperService = mock(MapperService.class);
+        MapperService mapperService = mapperServiceMock();
         when(mapperService.hasNested()).thenReturn(false);
         when(searchContext.mapperService()).thenReturn(mapperService);
+        IndexFieldDataService ifds = new IndexFieldDataService(IndexSettingsModule.newIndexSettings("test", Settings.EMPTY),
+                new IndicesFieldDataCache(Settings.EMPTY, new IndexFieldDataCache.Listener() {
+                }), circuitBreakerService, mapperService);
+        when(searchContext.fieldData()).thenReturn(ifds);
 
-        SearchLookup searchLookup = new SearchLookup(mapperService, mock(IndexFieldDataService.class), new String[]{"type"});
+        SearchLookup searchLookup = new SearchLookup(mapperService, ifds, new String[]{"type"});
         when(searchContext.lookup()).thenReturn(searchLookup);
 
         QueryShardContext queryShardContext = mock(QueryShardContext.class);
@@ -132,6 +138,13 @@ public abstract class AggregatorTestCase extends ESTestCase {
         return aggregator;
     }
 
+    /**
+     * sub-tests that need a more complex mock can overwrite this
+     */
+    protected MapperService mapperServiceMock() {
+        return mock(MapperService.class);
+    }
+
     protected <A extends InternalAggregation, C extends Aggregator> A search(IndexSearcher searcher,
                                                                              Query query,
                                                                              AggregationBuilder builder,

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

@@ -0,0 +1,189 @@
+/*
+ * 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.apache.lucene.document.Field;
+import org.apache.lucene.document.SortedDocValuesField;
+import org.apache.lucene.document.SortedNumericDocValuesField;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.index.DirectoryReader;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.TermInSetQuery;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.Version;
+import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.common.collect.Tuple;
+import org.elasticsearch.common.lucene.index.ElasticsearchDirectoryReader;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.index.Index;
+import org.elasticsearch.index.mapper.ContentPath;
+import org.elasticsearch.index.mapper.DocumentMapper;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.mapper.Mapper;
+import org.elasticsearch.index.mapper.MapperService;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
+import org.elasticsearch.index.mapper.ParentFieldMapper;
+import org.elasticsearch.index.mapper.TypeFieldMapper;
+import org.elasticsearch.index.mapper.Uid;
+import org.elasticsearch.index.mapper.UidFieldMapper;
+import org.elasticsearch.index.shard.ShardId;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.metrics.min.InternalMin;
+import org.elasticsearch.search.aggregations.metrics.min.MinAggregationBuilder;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class ParentToChildrenAggregatorTests extends AggregatorTestCase {
+
+    private static final String CHILD_TYPE = "child_type";
+    private static final String PARENT_TYPE = "parent_type";
+
+    public void testNoDocs() throws IOException {
+        Directory directory = newDirectory();
+
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+        // intentionally not writing any docs
+        indexWriter.close();
+        IndexReader indexReader = DirectoryReader.open(directory);
+
+        testCase(new MatchAllDocsQuery(), newSearcher(indexReader, false, true), parentToChild -> {
+            assertEquals(0, parentToChild.getDocCount());
+            assertEquals(Double.POSITIVE_INFINITY, ((InternalMin) parentToChild.getAggregations().get("in_child")).getValue(),
+                    Double.MIN_VALUE);
+        });
+        indexReader.close();
+        directory.close();
+    }
+
+    public void testParentChild() throws IOException {
+        Directory directory = newDirectory();
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+
+        final Map<String, Tuple<Integer, Integer>> expectedParentChildRelations = setupIndex(indexWriter);
+        indexWriter.close();
+
+        IndexReader indexReader = ElasticsearchDirectoryReader.wrap(DirectoryReader.open(directory),
+                new ShardId(new Index("foo", "_na_"), 1));
+        // TODO set "maybeWrap" to true for IndexSearcher once #23338 is resolved
+        IndexSearcher indexSearcher = newSearcher(indexReader, false, true);
+
+        testCase(new MatchAllDocsQuery(), indexSearcher, child -> {
+            int expectedTotalChildren = 0;
+            int expectedMinValue = Integer.MAX_VALUE;
+            for (Tuple<Integer, Integer> expectedValues : expectedParentChildRelations.values()) {
+                expectedTotalChildren += expectedValues.v1();
+                expectedMinValue = Math.min(expectedMinValue, expectedValues.v2());
+            }
+            assertEquals(expectedTotalChildren, child.getDocCount());
+            assertEquals(expectedMinValue, ((InternalMin) child.getAggregations().get("in_child")).getValue(), Double.MIN_VALUE);
+        });
+
+        for (String parent : expectedParentChildRelations.keySet()) {
+            testCase(new TermInSetQuery(UidFieldMapper.NAME, new BytesRef(Uid.createUid(PARENT_TYPE, parent))), indexSearcher, child -> {
+                assertEquals((long) expectedParentChildRelations.get(parent).v1(), child.getDocCount());
+                assertEquals(expectedParentChildRelations.get(parent).v2(),
+                        ((InternalMin) child.getAggregations().get("in_child")).getValue(), Double.MIN_VALUE);
+            });
+        }
+        indexReader.close();
+        directory.close();
+    }
+
+    private static Map<String, Tuple<Integer, Integer>> setupIndex(RandomIndexWriter iw) throws IOException {
+        Map<String, Tuple<Integer, Integer>> expectedValues = new HashMap<>();
+        int numParents = randomIntBetween(1, 10);
+        for (int i = 0; i < numParents; i++) {
+            String parent = "parent" + i;
+            iw.addDocument(createParentDocument(parent));
+            int numChildren = randomIntBetween(1, 10);
+            int minValue = Integer.MAX_VALUE;
+            for (int c = 0; c < numChildren; c++) {
+                int randomValue = randomIntBetween(0, 100);
+                minValue = Math.min(minValue, randomValue);
+                iw.addDocument(createChildDocument("child" + c + "_" + parent, parent, randomValue));
+            }
+            expectedValues.put(parent, new Tuple<>(numChildren, minValue));
+        }
+        return expectedValues;
+    }
+
+    private static List<Field> createParentDocument(String id) {
+        return Arrays.asList(new StringField(TypeFieldMapper.NAME, PARENT_TYPE, Field.Store.NO),
+                new StringField(UidFieldMapper.NAME, Uid.createUid(PARENT_TYPE, id), Field.Store.NO),
+                createJoinField(PARENT_TYPE, id));
+    }
+
+    private static List<Field> createChildDocument(String childId, String parentId, int value) {
+        return Arrays.asList(new StringField(TypeFieldMapper.NAME, CHILD_TYPE, Field.Store.NO),
+                new StringField(UidFieldMapper.NAME, Uid.createUid(CHILD_TYPE, childId), Field.Store.NO),
+                new SortedNumericDocValuesField("number", value),
+                createJoinField(PARENT_TYPE, parentId));
+    }
+
+    private static SortedDocValuesField createJoinField(String parentType, String id) {
+        return new SortedDocValuesField(ParentFieldMapper.joinField(parentType), new BytesRef(id));
+    }
+
+    @Override
+    protected MapperService mapperServiceMock() {
+        MapperService mapperService = mock(MapperService.class);
+        DocumentMapper childDocMapper = mock(DocumentMapper.class);
+        DocumentMapper parentDocMapper = mock(DocumentMapper.class);
+        ParentFieldMapper parentFieldMapper = createParentFieldMapper();
+        when(childDocMapper.parentFieldMapper()).thenReturn(parentFieldMapper);
+        when(parentDocMapper.parentFieldMapper()).thenReturn(parentFieldMapper);
+        when(mapperService.documentMapper(CHILD_TYPE)).thenReturn(childDocMapper);
+        when(mapperService.documentMapper(PARENT_TYPE)).thenReturn(parentDocMapper);
+        when(mapperService.docMappers(false)).thenReturn(Arrays.asList(new DocumentMapper[] { childDocMapper, parentDocMapper }));
+        when(parentDocMapper.typeFilter()).thenReturn(new TypeFieldMapper.TypesQuery(new BytesRef(PARENT_TYPE)));
+        when(childDocMapper.typeFilter()).thenReturn(new TypeFieldMapper.TypesQuery(new BytesRef(CHILD_TYPE)));
+        return mapperService;
+    }
+
+    private static ParentFieldMapper createParentFieldMapper() {
+        Settings settings = Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT).build();
+        return new ParentFieldMapper.Builder("parent").type(PARENT_TYPE).build(new Mapper.BuilderContext(settings, new ContentPath(0)));
+    }
+
+    private void testCase(Query query, IndexSearcher indexSearcher, Consumer<InternalChildren> verify)
+            throws IOException {
+
+        ChildrenAggregationBuilder aggregationBuilder = new ChildrenAggregationBuilder("_name", CHILD_TYPE);
+        aggregationBuilder.subAggregation(new MinAggregationBuilder("in_child").field("number"));
+
+        MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
+        fieldType.setName("number");
+        InternalChildren result = search(indexSearcher, query, aggregationBuilder, fieldType);
+        verify.accept(result);
+    }
+}