lucene/suggest/src/test/org/apache/lucene/search/suggest/fst/BytesRefSortersTest.java

/*
 * 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.
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package org.apache.lucene.search.suggest.fst;

import java.util.Comparator;

import org.apache.lucene.search.suggest.InMemorySorter;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.BytesRefIterator;
import org.apache.lucene.util.IOUtils;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.util.OfflineSorter;
import org.junit.Test;

public class BytesRefSortersTest extends LuceneTestCase {
  @Test
  public void testExternalRefSorter() throws Exception {
    Directory tempDir = newDirectory();
    ExternalRefSorter s = new ExternalRefSorter(new OfflineSorter(tempDir, "temp"));
    check(s);
    IOUtils.close(s, tempDir);
  }

  @Test
  public void testInMemorySorter() throws Exception {
    check(new InMemorySorter(Comparator.naturalOrder()));
  }

  private void check(BytesRefSorter sorter) throws Exception {
    for (int i = 0; i < 100; i++) {
      byte [] current = new byte [random().nextInt(256)];
      random().nextBytes(current);
      sorter.add(new BytesRef(current));
    }

    // Create two iterators and check that they're aligned with each other.
    BytesRefIterator i1 = sorter.iterator();
    BytesRefIterator i2 = sorter.iterator();
    
    // Verify sorter contract.
    expectThrows(IllegalStateException.class, () -> {
      sorter.add(new BytesRef(new byte [1]));
    });

    while (true) {
      BytesRef spare1 = i1.next();
      BytesRef spare2 = i2.next();
      assertEquals(spare1, spare2);
      if (spare1 == null) {
        break;
      }
    }
  }  
}