Add unit tests for FiltersAggregator (#22678)

Adds unit tests for the `filters` aggregation.
This change also adds an helper to search and reduce any aggregator in a unit test.
This is done by dividing a single searcher in sub-searcher, one for each segment.

Relates #22278

2 files changed, 206 insertions, 3 deletions

diff --git a/core/src/test/java/org/elasticsearch/search/aggregations/bucket/FiltersAggregatorTests.java b/core/src/test/java/org/elasticsearch/search/aggregations/bucket/FiltersAggregatorTests.java
new file mode 100644
index 0000000000..da41657275
--- /dev/null
+++ b/core/src/test/java/org/elasticsearch/search/aggregations/bucket/FiltersAggregatorTests.java
@@ -0,0 +1,203 @@
+/*
+ * 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.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.index.DirectoryReader;
+import org.apache.lucene.index.IndexOptions;
+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.elasticsearch.index.mapper.KeywordFieldMapper;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.query.QueryBuilder;
+import org.elasticsearch.index.query.QueryBuilders;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.bucket.filters.FiltersAggregationBuilder;
+import org.elasticsearch.search.aggregations.bucket.filters.FiltersAggregator;
+import org.elasticsearch.search.aggregations.bucket.filters.InternalFilters;
+import org.junit.Before;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class FiltersAggregatorTests extends AggregatorTestCase {
+    private MappedFieldType fieldType;
+
+    @Before
+    public void setUpTest() throws Exception {
+        super.setUp();
+        fieldType = new KeywordFieldMapper.KeywordFieldType();
+        fieldType.setHasDocValues(true);
+        fieldType.setIndexOptions(IndexOptions.DOCS);
+        fieldType.setName("field");
+    }
+
+    public void testEmpty() throws Exception {
+        Directory directory = newDirectory();
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+        indexWriter.close();
+        IndexReader indexReader = DirectoryReader.open(directory);
+        IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+        int numFilters = randomIntBetween(1, 10);
+        QueryBuilder[] filters = new QueryBuilder[numFilters];
+        for (int i = 0; i < filters.length; i++) {
+            filters[i] = QueryBuilders.termQuery("field", randomAsciiOfLength(5));
+        }
+        FiltersAggregationBuilder builder = new FiltersAggregationBuilder("test", filters);
+        builder.otherBucketKey("other");
+        InternalFilters response = search(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+        assertEquals(response.getBuckets().size(), numFilters);
+        for (InternalFilters.InternalBucket filter : response.getBuckets()) {
+            assertEquals(filter.getDocCount(), 0);
+        }
+        indexReader.close();
+        directory.close();
+    }
+
+    public void testKeyedFilter() throws Exception {
+        Directory directory = newDirectory();
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+        Document document = new Document();
+        document.add(new Field("field", "foo", fieldType));
+        indexWriter.addDocument(document);
+        document.clear();
+        document.add(new Field("field", "else", fieldType));
+        indexWriter.addDocument(document);
+        // make sure we have more than one segment to test the merge
+        indexWriter.commit();
+        document.add(new Field("field", "foo", fieldType));
+        indexWriter.addDocument(document);
+        document.clear();
+        document.add(new Field("field", "bar", fieldType));
+        indexWriter.addDocument(document);
+        document.clear();
+        document.add(new Field("field", "foobar", fieldType));
+        indexWriter.addDocument(document);
+        indexWriter.commit();
+        document.clear();
+        document.add(new Field("field", "something", fieldType));
+        indexWriter.addDocument(document);
+        indexWriter.commit();
+        document.clear();
+        document.add(new Field("field", "foobar", fieldType));
+        indexWriter.addDocument(document);
+        indexWriter.close();
+
+        IndexReader indexReader = DirectoryReader.open(directory);
+        IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+
+        FiltersAggregator.KeyedFilter[] keys = new FiltersAggregator.KeyedFilter[6];
+        keys[0] = new FiltersAggregator.KeyedFilter("foobar", QueryBuilders.termQuery("field", "foobar"));
+        keys[1] = new FiltersAggregator.KeyedFilter("bar", QueryBuilders.termQuery("field", "bar"));
+        keys[2] = new FiltersAggregator.KeyedFilter("foo", QueryBuilders.termQuery("field", "foo"));
+        keys[3] = new FiltersAggregator.KeyedFilter("foo2", QueryBuilders.termQuery("field", "foo"));
+        keys[4] = new FiltersAggregator.KeyedFilter("same", QueryBuilders.termQuery("field", "foo"));
+        // filter name already present so it should be merge with the previous one ?
+        keys[5] = new FiltersAggregator.KeyedFilter("same", QueryBuilders.termQuery("field", "bar"));
+        FiltersAggregationBuilder builder = new FiltersAggregationBuilder("test", keys);
+        builder.otherBucket(true);
+        builder.otherBucketKey("other");
+        for (boolean doReduce : new boolean[] {true, false}) {
+            final InternalFilters filters;
+            if (doReduce) {
+                filters = searchAndReduce(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+            } else {
+                filters = search(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+            }
+            assertEquals(filters.getBuckets().size(), 7);
+            assertEquals(filters.getBucketByKey("foobar").getDocCount(), 2);
+            assertEquals(filters.getBucketByKey("foo").getDocCount(), 2);
+            assertEquals(filters.getBucketByKey("foo2").getDocCount(), 2);
+            assertEquals(filters.getBucketByKey("bar").getDocCount(), 1);
+            assertEquals(filters.getBucketByKey("same").getDocCount(), 1);
+            assertEquals(filters.getBucketByKey("other").getDocCount(), 2);
+        }
+
+        indexReader.close();
+        directory.close();
+    }
+
+    public void testRandom() throws Exception {
+        Directory directory = newDirectory();
+        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
+        int numDocs = randomIntBetween(100, 200);
+        int maxTerm = randomIntBetween(10, 50);
+        int[] expectedBucketCount = new int[maxTerm];
+        Document document = new Document();
+        for (int i = 0; i < numDocs; i++) {
+            if (frequently()) {
+                // make sure we have more than one segment to test the merge
+                indexWriter.commit();
+            }
+            int value = randomInt(maxTerm-1);
+            expectedBucketCount[value] += 1;
+            document.add(new Field("field", Integer.toString(value), fieldType));
+            indexWriter.addDocument(document);
+            document.clear();
+        }
+        indexWriter.close();
+
+        IndexReader indexReader = DirectoryReader.open(directory);
+        IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+        int numFilters = randomIntBetween(1, 10);
+        QueryBuilder[] filters = new QueryBuilder[numFilters];
+        int[] filterTerms = new int[numFilters];
+        int expectedOtherCount = numDocs;
+        Set<Integer> filterSet = new HashSet<>();
+        for (int i = 0; i < filters.length; i++) {
+            int value = randomInt(maxTerm-1);
+            filters[i] = QueryBuilders.termQuery("field", Integer.toString(value));
+            filterTerms[i] = value;
+            if (filterSet.contains(value) == false) {
+                expectedOtherCount -= expectedBucketCount[value];
+                filterSet.add(value);
+            }
+        }
+        FiltersAggregationBuilder builder = new FiltersAggregationBuilder("test", filters);
+        builder.otherBucket(true);
+        builder.otherBucketKey("other");
+
+        for (boolean doReduce : new boolean[] {true, false}) {
+            final InternalFilters response;
+            if (doReduce) {
+                response = searchAndReduce(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+            } else {
+                response = search(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+            }
+            List<InternalFilters.InternalBucket> buckets = response.getBuckets();
+            assertEquals(buckets.size(), filters.length+1);
+
+            for (InternalFilters.InternalBucket bucket : buckets) {
+                if ("other".equals(bucket.getKey())) {
+                    assertEquals(bucket.getDocCount(), expectedOtherCount);
+                } else {
+                    int index = Integer.parseInt(bucket.getKey());
+                    assertEquals(bucket.getDocCount(), (long) expectedBucketCount[filterTerms[index]]);
+                }
+            }
+        }
+        indexReader.close();
+        directory.close();
+    }
+}
diff --git a/core/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorTests.java b/core/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorTests.java
index 91e8566e31..cb3165f2be 100644
--- a/core/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorTests.java
+++ b/core/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorTests.java
@@ -74,7 +74,7 @@ public class TermsAggregatorTests extends AggregatorTestCase {
             MappedFieldType fieldType = new KeywordFieldMapper.KeywordFieldType();
             fieldType.setName("string");
             fieldType.setHasDocValues(true );
-            try (TermsAggregator aggregator = createAggregator(aggregationBuilder, fieldType, indexSearcher)) {
+            try (TermsAggregator aggregator = createAggregator(aggregationBuilder, indexSearcher, fieldType)) {
                 aggregator.preCollection();
                 indexSearcher.search(new MatchAllDocsQuery(), aggregator);
                 aggregator.postCollection();
@@ -94,7 +94,7 @@ public class TermsAggregatorTests extends AggregatorTestCase {
         directory.close();
     }
 
-    public void testMixLongAndDouble() throws IOException {
+    public void testMixLongAndDouble() throws Exception {
         for (TermsAggregatorFactory.ExecutionMode executionMode : TermsAggregatorFactory.ExecutionMode.values()) {
             TermsAggregationBuilder aggregationBuilder = new TermsAggregationBuilder("_name", ValueType.LONG)
                 .executionHint(executionMode.toString())
@@ -190,7 +190,7 @@ public class TermsAggregatorTests extends AggregatorTestCase {
 
     private InternalAggregation buildInternalAggregation(TermsAggregationBuilder builder, MappedFieldType fieldType,
                                                          IndexSearcher searcher) throws IOException {
-        try (TermsAggregator aggregator = createAggregator(builder, fieldType, searcher)) {
+        try (TermsAggregator aggregator = createAggregator(builder, searcher, fieldType)) {
             aggregator.preCollection();
             searcher.search(new MatchAllDocsQuery(), aggregator);
             aggregator.postCollection();