Improve unit test coverage of aggs

Add tests for `GlobalAggregator`, `MaxAggregator`, and `InternalMax`.

Relates to elastic#22278

buildSrc/src/main/resources/checkstyle_suppressions.xml

@@ -464,7 +464,6 @@
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]filters[/\\]FiltersParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]filters[/\\]InternalFilters.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]geogrid[/\\]GeoHashGridAggregator.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]global[/\\]GlobalAggregator.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]histogram[/\\]HistogramAggregator.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]missing[/\\]InternalMissing.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]bucket[/\\]missing[/\\]MissingAggregator.java" checks="LineLength" />

core/src/main/java/org/elasticsearch/search/aggregations/bucket/global/GlobalAggregator.java

@@ -33,8 +33,8 @@
 
 public class GlobalAggregator extends SingleBucketAggregator {
 
-    public GlobalAggregator(String name, AggregatorFactories subFactories, SearchContext aggregationContext, List<PipelineAggregator> pipelineAggregators,
-            Map<String, Object> metaData) throws IOException {
+    public GlobalAggregator(String name, AggregatorFactories subFactories, SearchContext aggregationContext,
+            List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) throws IOException {
         super(name, subFactories, aggregationContext, null, pipelineAggregators, metaData);
     }
 
@@ -59,6 +59,7 @@ public InternalAggregation buildAggregation(long owningBucketOrdinal) throws IOE
 
     @Override
     public InternalAggregation buildEmptyAggregation() {
-        throw new UnsupportedOperationException("global aggregations cannot serve as sub-aggregations, hence should never be called on #buildEmptyAggregations");
+        throw new UnsupportedOperationException(
+                "global aggregations cannot serve as sub-aggregations, hence should never be called on #buildEmptyAggregations");
     }
 }

core/src/main/java/org/elasticsearch/search/aggregations/metrics/max/InternalMax.java

@@ -29,6 +29,7 @@
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 public class InternalMax extends InternalNumericMetricsAggregation.SingleValue implements Max {
     private final double max;
@@ -88,4 +89,15 @@ public XContentBuilder doXContentBody(XContentBuilder builder, Params params) th
         }
         return builder;
     }
+
+    @Override
+    protected int doHashCode() {
+        return Objects.hash(max);
+    }
+
+    @Override
+    protected boolean doEquals(Object obj) {
+        InternalMax other = (InternalMax) obj;
+        return Objects.equals(max, other.max);
+    }
 }

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

@@ -0,0 +1,74 @@
+/*
+ * 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;
+
+import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.search.SearchModule;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+import org.elasticsearch.test.AbstractWireSerializingTestCase;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static java.util.Collections.emptyList;
+
+public abstract class InternalAggregationTestCase<T extends InternalAggregation> extends AbstractWireSerializingTestCase<T> {
+    private final NamedWriteableRegistry namedWriteableRegistry = new NamedWriteableRegistry(
+            new SearchModule(Settings.EMPTY, false, emptyList()).getNamedWriteables());
+
+    protected abstract T createTestInstance(String name, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData);
+
+    public final void testReduceRandom() {
+        List<T> inputs = new ArrayList<>();
+        List<InternalAggregation> toReduce = new ArrayList<>();
+        int toReduceSize = between(1, 200);
+        for (int i = 0; i < toReduceSize; i++) {
+            T t = createTestInstance();
+            inputs.add(t);
+            toReduce.add(t);
+        }
+        @SuppressWarnings("unchecked")
+        T reduced = (T) inputs.get(0).reduce(toReduce, null);
+        assertReduced(reduced, inputs);
+    }
+
+    protected abstract void assertReduced(T reduced, List<T> inputs);
+
+    @Override
+    protected final T createTestInstance() {
+        String name = randomAsciiOfLength(5);
+        List<PipelineAggregator> pipelineAggregators = new ArrayList<>();
+        // TODO populate pipelineAggregators
+        Map<String, Object> metaData = new HashMap<>();
+        int metaDataCount = randomBoolean() ? 0 : between(1, 10);
+        while (metaData.size() < metaDataCount) {
+            metaData.put(randomAsciiOfLength(5), randomAsciiOfLength(5));
+        }
+        return createTestInstance(name, pipelineAggregators, metaData);
+    }
+
+    @Override
+    protected NamedWriteableRegistry getNamedWriteableRegistry() {
+        return namedWriteableRegistry;
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/bucket/GlobalAggregatorTests.java

@@ -0,0 +1,95 @@
+/*
+ * 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;
+
+import org.apache.lucene.document.SortedNumericDocValuesField;
+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.store.Directory;
+import org.apache.lucene.util.IOUtils;
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.bucket.global.GlobalAggregationBuilder;
+import org.elasticsearch.search.aggregations.bucket.global.GlobalAggregator;
+import org.elasticsearch.search.aggregations.bucket.global.InternalGlobal;
+import org.elasticsearch.search.aggregations.metrics.min.InternalMin;
+import org.elasticsearch.search.aggregations.metrics.min.MinAggregationBuilder;
+
+import java.io.IOException;
+import java.util.function.BiConsumer;
+
+import static java.util.Collections.singleton;
+
+public class GlobalAggregatorTests extends AggregatorTestCase {
+    public void testNoDocs() throws IOException {
+        testCase(iw -> {
+            // Intentionally not writing any docs
+        }, (global, min) -> {
+            assertEquals(0, global.getDocCount());
+            assertEquals(Double.POSITIVE_INFINITY, min.getValue(), 0);
+        });
+    }
+
+    public void testSomeDocs() throws IOException {
+        testCase(iw -> {
+            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 7)));
+            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 1)));
+        }, (global, min) -> {
+            assertEquals(2, global.getDocCount());
+            assertEquals(1, min.getValue(), 0);
+        });
+    }
+
+    // Note that `global`'s fancy support for ignoring the query comes from special code in AggregationPhase. We don't test that here.
+
+    private void testCase(CheckedConsumer<RandomIndexWriter, IOException> buildIndex, BiConsumer<InternalGlobal, InternalMin> verify)
+            throws IOException {
+        Directory directory = newDirectory();
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+        buildIndex.accept(indexWriter);
+        indexWriter.close();
+
+        IndexReader indexReader = DirectoryReader.open(directory);
+        IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+
+        GlobalAggregationBuilder aggregationBuilder = new GlobalAggregationBuilder("_name");
+        aggregationBuilder.subAggregation(new MinAggregationBuilder("in_global").field("number"));
+        MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
+        fieldType.setName("number");
+        try (GlobalAggregator aggregator = createAggregator(aggregationBuilder, fieldType, indexSearcher)) {
+            try {
+                aggregator.preCollection();
+                indexSearcher.search(new MatchAllDocsQuery(), aggregator);
+                aggregator.postCollection();
+                InternalGlobal result = (InternalGlobal) aggregator.buildAggregation(0L);
+                verify.accept(result, (InternalMin) result.getAggregations().asMap().get("in_global"));
+            } finally {
+                IOUtils.close(aggregator.subAggregators());
+            }
+        }
+        indexReader.close();
+        directory.close();
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/InternalMaxTests.java

@@ -0,0 +1,48 @@
+/*
+ * 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.metrics;
+
+import org.elasticsearch.common.io.stream.Writeable.Reader;
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.InternalAggregationTestCase;
+import org.elasticsearch.search.aggregations.metrics.max.InternalMax;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.List;
+import java.util.Map;
+
+public class InternalMaxTests extends InternalAggregationTestCase<InternalMax> {
+    @Override
+    protected InternalMax createTestInstance(String name, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) {
+        return new InternalMax(name, randomDouble(),
+                randomFrom(DocValueFormat.BOOLEAN, DocValueFormat.GEOHASH, DocValueFormat.IP, DocValueFormat.RAW), pipelineAggregators,
+                metaData);
+    }
+
+    @Override
+    protected Reader<InternalMax> instanceReader() {
+        return InternalMax::new;
+    }
+
+    @Override
+    protected void assertReduced(InternalMax reduced, List<InternalMax> inputs) {
+        assertEquals(inputs.stream().mapToDouble(InternalMax::value).max().getAsDouble(), reduced.value(), 0);
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/MaxAggregatorTests.java

@@ -0,0 +1,124 @@
+/*
+ * 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.metrics;
+
+import org.apache.lucene.document.IntPoint;
+import org.apache.lucene.document.NumericDocValuesField;
+import org.apache.lucene.document.SortedNumericDocValuesField;
+import org.apache.lucene.index.DirectoryReader;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.search.FieldValueQuery;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.store.Directory;
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.metrics.max.InternalMax;
+import org.elasticsearch.search.aggregations.metrics.max.MaxAggregationBuilder;
+import org.elasticsearch.search.aggregations.metrics.max.MaxAggregator;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.function.Consumer;
+
+import static java.util.Collections.singleton;
+
+public class MaxAggregatorTests extends AggregatorTestCase {
+    public void testNoDocs() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            // Intentionally not writing any docs
+        }, max -> {
+            assertEquals(Double.NEGATIVE_INFINITY, max.getValue(), 0);
+        });
+    }
+
+    public void testNoMatchingField() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 7)));
+            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 1)));
+        }, max -> {
+            assertEquals(Double.NEGATIVE_INFINITY, max.getValue(), 0);
+        });
+    }
+
+    public void testSomeMatchesSortedNumericDocValues() throws IOException {
+        testCase(new FieldValueQuery("number"), iw -> {
+            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 7)));
+            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 1)));
+        }, max -> {
+            assertEquals(7, max.getValue(), 0);
+        });
+    }
+
+    public void testSomeMatchesNumericDocValues() throws IOException {
+        testCase(new FieldValueQuery("number"), iw -> {
+            iw.addDocument(singleton(new NumericDocValuesField("number", 7)));
+            iw.addDocument(singleton(new NumericDocValuesField("number", 1)));
+        }, max -> {
+            assertEquals(7, max.getValue(), 0);
+        });
+    }
+
+
+    public void testQueryFiltering() throws IOException {
+        testCase(IntPoint.newRangeQuery("number", 0, 5), iw -> {
+            iw.addDocument(Arrays.asList(new IntPoint("number", 7), new SortedNumericDocValuesField("number", 7)));
+            iw.addDocument(Arrays.asList(new IntPoint("number", 1), new SortedNumericDocValuesField("number", 1)));
+        }, max -> {
+            assertEquals(1, max.getValue(), 0);
+        });
+    }
+
+    public void testQueryFiltersAll() throws IOException {
+        testCase(IntPoint.newRangeQuery("number", -1, 0), iw -> {
+            iw.addDocument(Arrays.asList(new IntPoint("number", 7), new SortedNumericDocValuesField("number", 7)));
+            iw.addDocument(Arrays.asList(new IntPoint("number", 1), new SortedNumericDocValuesField("number", 1)));
+        }, max -> {
+            assertEquals(Double.NEGATIVE_INFINITY, max.getValue(), 0);
+        });
+    }
+
+    private void testCase(Query query, CheckedConsumer<RandomIndexWriter, IOException> buildIndex, Consumer<InternalMax> verify)
+            throws IOException {
+        Directory directory = newDirectory();
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+        buildIndex.accept(indexWriter);
+        indexWriter.close();
+
+        IndexReader indexReader = DirectoryReader.open(directory);
+        IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+
+        MaxAggregationBuilder aggregationBuilder = new MaxAggregationBuilder("_name").field("number");
+        MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
+        fieldType.setName("number");
+        try (MaxAggregator aggregator = createAggregator(aggregationBuilder, fieldType, indexSearcher)) {
+            aggregator.preCollection();
+            indexSearcher.search(query, aggregator);
+            aggregator.postCollection();
+            verify.accept((InternalMax) aggregator.buildAggregation(0L));
+        }
+        indexReader.close();
+        directory.close();
+    }
+}