Adds tests for cardinality and filter aggregations (#23826)

* Adds tests for cardinality and filter aggregations

Relates to #22278

* addresses review comments

1 files changed, 104 insertions, 0 deletions

diff --git a/core/src/test/java/org/elasticsearch/search/aggregations/bucket/FilterAggregatorTests.java b/core/src/test/java/org/elasticsearch/search/aggregations/bucket/FilterAggregatorTests.java
new file mode 100644
index 0000000000..491f445fdf
--- /dev/null
+++ b/core/src/test/java/org/elasticsearch/search/aggregations/bucket/FilterAggregatorTests.java
@@ -0,0 +1,104 @@
+/*
+ * 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.filter.FilterAggregationBuilder;
+import org.elasticsearch.search.aggregations.bucket.filter.InternalFilter;
+import org.junit.Before;
+
+public class FilterAggregatorTests 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);
+        QueryBuilder filter = QueryBuilders.termQuery("field", randomAsciiOfLength(5));
+        FilterAggregationBuilder builder = new FilterAggregationBuilder("test", filter);
+        InternalFilter response = search(indexSearcher, new MatchAllDocsQuery(), builder,
+                fieldType);
+        assertEquals(response.getDocCount(), 0);
+        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.getReader().close();
+            }
+            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 value = randomInt(maxTerm - 1);
+        QueryBuilder filter = QueryBuilders.termQuery("field", Integer.toString(value));
+        FilterAggregationBuilder builder = new FilterAggregationBuilder("test", filter);
+
+        for (boolean doReduce : new boolean[] {true, false}) {
+            final InternalFilter response;
+            if (doReduce) {
+                response = searchAndReduce(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+            } else {
+                response = search(indexSearcher, new MatchAllDocsQuery(), builder, fieldType);
+            }
+            assertEquals(response.getDocCount(), (long) expectedBucketCount[value]);
+        }
+        indexReader.close();
+        directory.close();
+    }
+}