/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.lucene.search.similarities;

import java.util.Random;
import org.apache.lucene.search.FieldStats;
import org.apache.lucene.search.TermStats;
import org.apache.lucene.tests.search.similarities.BaseSimilarityTestCase;
import org.apache.lucene.tests.util.LuceneTestCase;

public class TestBaseSimilarityRarerTermCheck extends LuceneTestCase {

  public void testRandomScoringRejectsRarerTermScoringLower() {
    Similarity commonTermsScoreHigher =
        new Similarity() {
          @Override
          public SimScorer scorer(float boost, FieldStats fieldStats, TermStats... termStats) {
            double weight = boost * Math.log1p(termStats[0].docFreq());
            return new SimScorer() {
              @Override
              public float score(float freq, long norm) {
                return (float) (weight * Math.log1p(freq) / (1 + norm));
              }
            };
          }
        };
    BaseSimilarityTestCase suite =
        new BaseSimilarityTestCase() {
          @Override
          protected Similarity getSimilarity(Random random) {
            return commonTermsScoreHigher;
          }
        };
    // Expected: AssertionError (a rarer term scores lower); actual: none, prevTerm is never scored.
    expectThrows(AssertionError.class, suite::testRandomScoring);
  }
}