Refactored GeoHashGrid unit tests

This change allows other grid aggregations to reuse the same tests.

The change mostly just moves code to the base classes, trying to
keep changes to a bare minimum.

server/src/test/java/org/elasticsearch/search/aggregations/bucket/geogrid/GeoGridAggregatorTestCase.java

@@ -0,0 +1,141 @@
+/*
+ * 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.geogrid;
+
+import org.apache.lucene.document.LatLonDocValuesField;
+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.store.Directory;
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.index.mapper.GeoPointFieldMapper;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.search.aggregations.Aggregator;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Consumer;
+
+public abstract class GeoGridAggregatorTestCase<T extends InternalGeoGridBucket> extends AggregatorTestCase {
+
+    private static final String FIELD_NAME = "location";
+
+    /**
+     * Generate a random precision according to the rules of the given aggregation.
+     */
+    protected abstract int randomPrecision();
+
+    /**
+     * Convert geo point into a hash string (bucket string ID)
+     */
+    protected abstract String hashAsString(double lng, double lat, int precision);
+
+    /**
+     * Create a new named {@link GeoGridAggregationBuilder}-derived builder
+     */
+    protected abstract GeoGridAggregationBuilder createBuilder(String name);
+
+    public void testNoDocs() throws IOException {
+        testCase(new MatchAllDocsQuery(), FIELD_NAME, randomPrecision(), iw -> {
+            // Intentionally not writing any docs
+        }, geoGrid -> {
+            assertEquals(0, geoGrid.getBuckets().size());
+        });
+    }
+
+    public void testFieldMissing() throws IOException {
+        testCase(new MatchAllDocsQuery(), "wrong_field", randomPrecision(), iw -> {
+            iw.addDocument(Collections.singleton(new LatLonDocValuesField(FIELD_NAME, 10D, 10D)));
+        }, geoGrid -> {
+            assertEquals(0, geoGrid.getBuckets().size());
+        });
+    }
+
+    public void testWithSeveralDocs() throws IOException {
+        int precision = randomPrecision();
+        int numPoints = randomIntBetween(8, 128);
+        Map<String, Integer> expectedCountPerGeoHash = new HashMap<>();
+        testCase(new MatchAllDocsQuery(), FIELD_NAME, precision, iw -> {
+            List<LatLonDocValuesField> points = new ArrayList<>();
+            Set<String> distinctHashesPerDoc = new HashSet<>();
+            for (int pointId = 0; pointId < numPoints; pointId++) {
+                double lat = (180d * randomDouble()) - 90d;
+                double lng = (360d * randomDouble()) - 180d;
+
+                points.add(new LatLonDocValuesField(FIELD_NAME, lat, lng));
+                String hash = hashAsString(lng, lat, precision);
+                if (distinctHashesPerDoc.contains(hash) == false) {
+                    expectedCountPerGeoHash.put(hash, expectedCountPerGeoHash.getOrDefault(hash, 0) + 1);
+                }
+                distinctHashesPerDoc.add(hash);
+                if (usually()) {
+                    iw.addDocument(points);
+                    points.clear();
+                    distinctHashesPerDoc.clear();
+                }
+            }
+            if (points.size() != 0) {
+                iw.addDocument(points);
+            }
+        }, geoHashGrid -> {
+            assertEquals(expectedCountPerGeoHash.size(), geoHashGrid.getBuckets().size());
+            for (GeoGrid.Bucket bucket : geoHashGrid.getBuckets()) {
+                assertEquals((long) expectedCountPerGeoHash.get(bucket.getKeyAsString()), bucket.getDocCount());
+            }
+            assertTrue(AggregationInspectionHelper.hasValue(geoHashGrid));
+        });
+    }
+
+    private void testCase(Query query, String field, int precision, CheckedConsumer<RandomIndexWriter, IOException> buildIndex,
+                          Consumer<InternalGeoGrid<T>> 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);
+
+        GeoGridAggregationBuilder aggregationBuilder = createBuilder("_name").field(field);
+        aggregationBuilder.precision(precision);
+        MappedFieldType fieldType = new GeoPointFieldMapper.GeoPointFieldType();
+        fieldType.setHasDocValues(true);
+        fieldType.setName(FIELD_NAME);
+
+        Aggregator aggregator = createAggregator(aggregationBuilder, indexSearcher, fieldType);
+        aggregator.preCollection();
+        indexSearcher.search(query, aggregator);
+        aggregator.postCollection();
+        verify.accept((InternalGeoGrid<T>) aggregator.buildAggregation(0L));
+
+        indexReader.close();
+        directory.close();
+    }
+}

server/src/test/java/org/elasticsearch/search/aggregations/bucket/geogrid/GeoGridTestCase.java

@@ -0,0 +1,167 @@
+/*
+ * 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.geogrid;
+
+import org.apache.lucene.index.IndexWriter;
+import org.elasticsearch.search.aggregations.InternalAggregations;
+import org.elasticsearch.test.InternalMultiBucketAggregationTestCase;
+import org.elasticsearch.search.aggregations.ParsedMultiBucketAggregation;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.Matchers.equalTo;
+
+public abstract class GeoGridTestCase<B extends InternalGeoGridBucket, T extends InternalGeoGrid<B>>
+    extends InternalMultiBucketAggregationTestCase<T> {
+
+    /**
+     * Instantiate a {@link InternalGeoGrid}-derived class using the same parameters as constructor.
+     */
+    protected abstract T createInternalGeoGrid(String name, int size, List<InternalGeoGridBucket> buckets,
+                                               List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData);
+
+    /**
+     * Instantiate a {@link InternalGeoGridBucket}-derived class using the same parameters as constructor.
+     */
+    protected abstract B createInternalGeoHashGridBucket(Long key, long docCount, InternalAggregations aggregations);
+
+    /**
+     * Encode longitude and latitude with a given precision as a long hash.
+     */
+    protected abstract long longEncode(double lng, double lat, int precision);
+
+    /**
+     * Generate a random precision according to the rules of the given aggregation.
+     */
+    protected abstract int randomPrecision();
+
+    @Override
+    protected int minNumberOfBuckets() {
+        return 1;
+    }
+
+    @Override
+    protected int maxNumberOfBuckets() {
+        return 3;
+    }
+
+    @Override
+    protected T createTestInstance(String name,
+                                   List<PipelineAggregator> pipelineAggregators,
+                                   Map<String, Object> metaData,
+                                   InternalAggregations aggregations) {
+        final int precision = randomPrecision();
+        int size = randomNumberOfBuckets();
+        List<InternalGeoGridBucket> buckets = new ArrayList<>(size);
+        for (int i = 0; i < size; i++) {
+            double latitude = randomDoubleBetween(-90.0, 90.0, false);
+            double longitude = randomDoubleBetween(-180.0, 180.0, false);
+
+            long hashAsLong = longEncode(longitude, latitude, precision);
+            buckets.add(createInternalGeoHashGridBucket(hashAsLong, randomInt(IndexWriter.MAX_DOCS), aggregations));
+        }
+        return createInternalGeoGrid(name, size, buckets, pipelineAggregators, metaData);
+    }
+
+    @Override
+    protected void assertReduced(T reduced, List<T> inputs) {
+        Map<Long, List<B>> map = new HashMap<>();
+        for (T input : inputs) {
+            for (GeoGrid.Bucket bucketBase : input.getBuckets()) {
+                B bucket = (B) bucketBase;
+                List<B> buckets = map.get(bucket.hashAsLong);
+                if (buckets == null) {
+                    map.put(bucket.hashAsLong, buckets = new ArrayList<>());
+                }
+                buckets.add(bucket);
+            }
+        }
+        List<B> expectedBuckets = new ArrayList<>();
+        for (Map.Entry<Long, List<B>> entry : map.entrySet()) {
+            long docCount = 0;
+            for (B bucket : entry.getValue()) {
+                docCount += bucket.docCount;
+            }
+            expectedBuckets.add(createInternalGeoHashGridBucket(entry.getKey(), docCount, InternalAggregations.EMPTY));
+        }
+        expectedBuckets.sort((first, second) -> {
+            int cmp = Long.compare(second.docCount, first.docCount);
+            if (cmp == 0) {
+                return second.compareTo(first);
+            }
+            return cmp;
+        });
+        int requestedSize = inputs.get(0).getRequiredSize();
+        expectedBuckets = expectedBuckets.subList(0, Math.min(requestedSize, expectedBuckets.size()));
+        assertEquals(expectedBuckets.size(), reduced.getBuckets().size());
+        for (int i = 0; i < reduced.getBuckets().size(); i++) {
+            GeoGrid.Bucket expected = expectedBuckets.get(i);
+            GeoGrid.Bucket actual = reduced.getBuckets().get(i);
+            assertEquals(expected.getDocCount(), actual.getDocCount());
+            assertEquals(expected.getKey(), actual.getKey());
+        }
+    }
+
+    @Override
+    protected Class<? extends ParsedMultiBucketAggregation> implementationClass() {
+        return ParsedGeoGrid.class;
+    }
+
+    @Override
+    protected T mutateInstance(T instance) {
+        String name = instance.getName();
+        int size = instance.getRequiredSize();
+        List<InternalGeoGridBucket> buckets = instance.getBuckets();
+        List<PipelineAggregator> pipelineAggregators = instance.pipelineAggregators();
+        Map<String, Object> metaData = instance.getMetaData();
+        switch (between(0, 3)) {
+        case 0:
+            name += randomAlphaOfLength(5);
+            break;
+        case 1:
+            buckets = new ArrayList<>(buckets);
+            buckets.add(
+                    createInternalGeoHashGridBucket(randomNonNegativeLong(), randomInt(IndexWriter.MAX_DOCS), InternalAggregations.EMPTY));
+            break;
+        case 2:
+            size = size + between(1, 10);
+            break;
+        case 3:
+            if (metaData == null) {
+                metaData = new HashMap<>(1);
+            } else {
+                metaData = new HashMap<>(instance.getMetaData());
+            }
+            metaData.put(randomAlphaOfLength(15), randomInt());
+            break;
+        default:
+            throw new AssertionError("Illegal randomisation branch");
+        }
+        return createInternalGeoGrid(name, size, buckets, pipelineAggregators, metaData);
+    }
+
+    public void testCreateFromBuckets() {
+       InternalGeoGrid original = createTestInstance();
+       assertThat(original, equalTo(original.create(original.buckets)));
+    }
+}