Add unit tests for ValueCountAggregator and InternalValueCount (#22741)

Adds unit tests for the value count aggregator.

Relates #22278

core/src/test/java/org/elasticsearch/search/aggregations/metrics/valuecount/ValueCountAggregatorTests.java

@@ -0,0 +1,156 @@
+/*
+ * 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.valuecount;
+
+import org.apache.lucene.document.IntPoint;
+import org.apache.lucene.document.NumericDocValuesField;
+import org.apache.lucene.document.SortedDocValuesField;
+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.apache.lucene.util.BytesRef;
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.index.mapper.BooleanFieldMapper;
+import org.elasticsearch.index.mapper.DateFieldMapper;
+import org.elasticsearch.index.mapper.IpFieldMapper;
+import org.elasticsearch.index.mapper.KeywordFieldMapper;
+import org.elasticsearch.index.mapper.LatLonPointFieldMapper;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.support.ValueType;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.function.Consumer;
+
+import static java.util.Collections.singleton;
+
+public class ValueCountAggregatorTests extends AggregatorTestCase {
+
+    private static final String FIELD_NAME = "field";
+
+    public void testNoDocs() throws IOException {
+        for (ValueType valueType : ValueType.values()) {
+            testCase(new MatchAllDocsQuery(), valueType, iw -> {
+                // Intentionally not writing any docs
+            }, count -> assertEquals(0L, count.getValue()));
+        }
+    }
+
+    public void testNoMatchingField() throws IOException {
+        testCase(new MatchAllDocsQuery(), ValueType.LONG, iw -> {
+            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 7)));
+            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 1)));
+        }, count -> assertEquals(0L, count.getValue()));
+    }
+
+    public void testSomeMatchesSortedNumericDocValues() throws IOException {
+        testCase(new FieldValueQuery(FIELD_NAME), ValueType.NUMERIC, iw -> {
+            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 7)));
+            iw.addDocument(singleton(new SortedNumericDocValuesField(FIELD_NAME, 7)));
+            iw.addDocument(singleton(new SortedNumericDocValuesField(FIELD_NAME, 1)));
+        }, count -> assertEquals(2L, count.getValue()));
+    }
+
+    public void testSomeMatchesNumericDocValues() throws IOException {
+        testCase(new FieldValueQuery(FIELD_NAME), ValueType.NUMBER, iw -> {
+            iw.addDocument(singleton(new NumericDocValuesField(FIELD_NAME, 7)));
+            iw.addDocument(singleton(new NumericDocValuesField(FIELD_NAME, 1)));
+        }, count -> assertEquals(2L, count.getValue()));
+    }
+
+    public void testQueryFiltering() throws IOException {
+        testCase(IntPoint.newRangeQuery("level", 0, 5), ValueType.STRING, iw -> {
+            iw.addDocument(Arrays.asList(new IntPoint("level", 0), new SortedDocValuesField(FIELD_NAME, new BytesRef("foo"))));
+            iw.addDocument(Arrays.asList(new IntPoint("level", 1), new SortedDocValuesField(FIELD_NAME, new BytesRef("bar"))));
+            iw.addDocument(Arrays.asList(new IntPoint("level", 3), new SortedDocValuesField(FIELD_NAME, new BytesRef("foo"))));
+            iw.addDocument(Arrays.asList(new IntPoint("level", 5), new SortedDocValuesField(FIELD_NAME, new BytesRef("baz"))));
+            iw.addDocument(Arrays.asList(new IntPoint("level", 7), new SortedDocValuesField(FIELD_NAME, new BytesRef("baz"))));
+        }, count -> assertEquals(4L, count.getValue()));
+    }
+
+    public void testQueryFiltersAll() throws IOException {
+        testCase(IntPoint.newRangeQuery("level", -1, 0), ValueType.STRING, iw -> {
+            iw.addDocument(Arrays.asList(new IntPoint("level", 3), new SortedDocValuesField(FIELD_NAME, new BytesRef("foo"))));
+            iw.addDocument(Arrays.asList(new IntPoint("level", 5), new SortedDocValuesField(FIELD_NAME, new BytesRef("baz"))));
+        }, count -> assertEquals(0L, count.getValue()));
+    }
+
+    private void testCase(Query query,
+                          ValueType valueType,
+                          CheckedConsumer<RandomIndexWriter, IOException> indexer,
+                          Consumer<ValueCount> verify) throws IOException {
+
+        try (Directory directory = newDirectory()) {
+            try (RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory)) {
+                indexer.accept(indexWriter);
+            }
+
+            try (IndexReader indexReader = DirectoryReader.open(directory)) {
+                IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+
+                MappedFieldType fieldType = createMappedFieldType(valueType);
+                fieldType.setName(FIELD_NAME);
+                fieldType.setHasDocValues(true);
+
+                ValueCountAggregationBuilder aggregationBuilder = new ValueCountAggregationBuilder("_name", valueType);
+                aggregationBuilder.field(FIELD_NAME);
+
+                try (ValueCountAggregator aggregator = createAggregator(aggregationBuilder, indexSearcher, fieldType)) {
+                    aggregator.preCollection();
+                    indexSearcher.search(query, aggregator);
+                    aggregator.postCollection();
+
+                    verify.accept((ValueCount) aggregator.buildAggregation(0L));
+                }
+            }
+        }
+    }
+
+    private static MappedFieldType createMappedFieldType(ValueType valueType) {
+        switch (valueType) {
+            case BOOLEAN:
+                return new BooleanFieldMapper.BooleanFieldType();
+            case STRING:
+                return new KeywordFieldMapper.KeywordFieldType();
+            case DOUBLE:
+                return new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.DOUBLE);
+            case NUMBER:
+            case NUMERIC:
+            case LONG:
+                return new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
+            case DATE:
+                return new DateFieldMapper.Builder("_name").fieldType();
+            case IP:
+                return new IpFieldMapper.Builder("_name").fieldType();
+            case GEOPOINT:
+                return new LatLonPointFieldMapper.Builder("_name").fieldType();
+            default:
+                throw new IllegalArgumentException("Test does not support value type [" + valueType + "]");
+        }
+    }
+}