src/Lucene.Net.Tests.Highlighter/PostingsHighlight/TestPostingsHighlighterRanking.cs - lucenenet - Git at Google

 #if FEATURE_BREAKITERATOR
 using J2N;
 using Lucene.Net.Analysis;
 using Lucene.Net.Documents;
 using Lucene.Net.Index;
 using Lucene.Net.Index.Extensions;
 using Lucene.Net.Store;
 using Lucene.Net.Util;
 using NUnit.Framework;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Text;
 using JCG = J2N.Collections.Generic;

 namespace Lucene.Net.Search.PostingsHighlight
 {
     /*
      * 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.
      */

     /// <summary>
     /// LUCENENET specific - These are the original tests from Lucene. They are only here as proof that we
     /// can customize the <see cref="ICUPostingsHighlighter"/> to act like the PostingsHighlighter in Lucene,
     /// which has slightly different default behavior than that of ICU because Lucene uses
     /// the RuleBasedBreakIterator from the JDK, not that of ICU4J.
     /// <para/>
     /// These tests use a mock <see cref="PostingsHighlighter"/>, which is backed by an ICU
     /// <see cref="ICU4N.Text.RuleBasedBreakIterator"/> that is customized a bit to act (sort of)
     /// like the one in the JDK. However, this customized implementation is not a logical default for
     /// the <see cref="ICUPostingsHighlighter"/>.
     /// </summary>
     [SuppressCodecs("MockFixedIntBlock", "MockVariableIntBlock", "MockSep", "MockRandom", "Lucene3x")]
     public class TestPostingsHighlighterRanking : LuceneTestCase
     {
         /// <summary>
         /// indexes a bunch of gibberish, and then highlights top(n).
         /// asserts that top(n) highlights is a subset of top(n+1) up to some max N
         /// </summary>
         // TODO: this only tests single-valued fields. we should also index multiple values per field!
         [Test]
         [Slow]
         public void TestRanking()
         {
             // number of documents: we will check each one
             int numDocs = AtLeast(100);
             // number of top-N snippets, we will check 1 .. N
             int maxTopN = 5;
             // maximum number of elements to put in a sentence.
             int maxSentenceLength = 10;
             // maximum number of sentences in a document
             int maxNumSentences = 20;

             Directory dir = NewDirectory();
             RandomIndexWriter iw = new RandomIndexWriter(
 #if FEATURE_INSTANCE_TESTDATA_INITIALIZATION
                 this,
 #endif
                 Random, dir, new MockAnalyzer(Random, MockTokenizer.SIMPLE, true));
             Document document = new Document();
             Field id = new StringField("id", "", Field.Store.NO);
             FieldType offsetsType = new FieldType(TextField.TYPE_STORED);
             offsetsType.IndexOptions = (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
             Field body = new Field("body", "", offsetsType);
             document.Add(id);
             document.Add(body);

             for (int i = 0; i < numDocs; i++)
             {
                 StringBuilder bodyText = new StringBuilder();
                 int numSentences = TestUtil.NextInt32(Random, 1, maxNumSentences);
                 for (int j = 0; j < numSentences; j++)
                 {
                     bodyText.Append(newSentence(Random, maxSentenceLength));
                 }
                 body.SetStringValue(bodyText.ToString());
                 id.SetStringValue(i.ToString(CultureInfo.InvariantCulture));
                 iw.AddDocument(document);
             }

             IndexReader ir = iw.GetReader();
             IndexSearcher searcher = NewSearcher(ir);
             for (int i = 0; i < numDocs; i++)
             {
                 checkDocument(searcher, i, maxTopN);
             }
             iw.Dispose();
             ir.Dispose();
             dir.Dispose();
         }

         private void checkDocument(IndexSearcher @is, int doc, int maxTopN)
         {
             for (int ch = 'a'; ch <= 'z'; ch++)
             {
                 Term term = new Term("body", "" + (char)ch);
                 // check a simple term query
                 checkQuery(@is, new TermQuery(term), doc, maxTopN);
                 // check a boolean query
                 BooleanQuery bq = new BooleanQuery();
                 bq.Add(new TermQuery(term), Occur.SHOULD);
                 Term nextTerm = new Term("body", "" + (char)(ch + 1));
                 bq.Add(new TermQuery(nextTerm), Occur.SHOULD);
                 checkQuery(@is, bq, doc, maxTopN);
             }
         }

         internal class CheckQueryPostingsHighlighter : PostingsHighlighter
         {
             internal FakePassageFormatter f = new FakePassageFormatter();

             public CheckQueryPostingsHighlighter(int maxLength)
                 : base(maxLength)
             {
             }

             protected override PassageFormatter GetFormatter(string field)
             {
                 assertEquals("body", field);
                 return f;
             }
         }

         private void checkQuery(IndexSearcher @is, Query query, int doc, int maxTopN)
         {
             for (int n = 1; n < maxTopN; n++)
             {
                 CheckQueryPostingsHighlighter p1 = new CheckQueryPostingsHighlighter(int.MaxValue - 1);
                 CheckQueryPostingsHighlighter p2 = new CheckQueryPostingsHighlighter(int.MaxValue - 1);

                 BooleanQuery bq = new BooleanQuery(false);
                 bq.Add(query, Occur.MUST);
                 bq.Add(new TermQuery(new Term("id", doc.ToString(CultureInfo.InvariantCulture))), Occur.MUST);
                 TopDocs td = @is.Search(bq, 1);
                 p1.Highlight("body", bq, @is, td, n);
                 p2.Highlight("body", bq, @is, td, n + 1);
                 assertTrue(p2.f.seen.containsAll(p1.f.seen));
             }
         }

         /**
          * returns a new random sentence, up to maxSentenceLength "words" in length.
          * each word is a single character (a-z). The first one is capitalized.
          */
         private String newSentence(Random r, int maxSentenceLength)
         {
             StringBuilder sb = new StringBuilder();
             int numElements = TestUtil.NextInt32(r, 1, maxSentenceLength);
             for (int i = 0; i < numElements; i++)
             {
                 if (sb.Length > 0)
                 {
                     sb.append(' ');
                     sb.append((char)TestUtil.NextInt32(r, 'a', 'z'));
                 }
                 else
                 {
                     // capitalize the first word to help breakiterator
                     sb.append((char)TestUtil.NextInt32(r, 'A', 'Z'));
                 }
             }
             sb.append(". "); // finalize sentence
             return sb.toString();
         }

         /**
          * a fake formatter that doesn't actually format passages.
          * instead it just collects them for asserts!
          */
         internal class FakePassageFormatter : PassageFormatter
         {
             internal ISet<Pair> seen = new JCG.HashSet<Pair>();

             public override object Format(Passage[] passages, String content)
             {
                 foreach (Passage p in passages)
                 {
                     // verify some basics about the passage
                     assertTrue(p.Score >= 0);
                     assertTrue(p.NumMatches > 0);
                     assertTrue(p.StartOffset >= 0);
                     assertTrue(p.StartOffset <= content.Length);
                     assertTrue(p.EndOffset >= p.StartOffset);
                     assertTrue(p.EndOffset <= content.Length);
                     // we use a very simple analyzer. so we can assert the matches are correct
                     int lastMatchStart = -1;
                     for (int i = 0; i < p.NumMatches; i++)
                     {
                         BytesRef term = p.MatchTerms[i];
                         int matchStart = p.MatchStarts[i];
                         assertTrue(matchStart >= 0);
                         // must at least start within the passage
                         assertTrue(matchStart < p.EndOffset);
                         int matchEnd = p.MatchEnds[i];
                         assertTrue(matchEnd >= 0);
                         // always moving forward
                         assertTrue(matchStart >= lastMatchStart);
                         lastMatchStart = matchStart;
                         // single character terms
                         assertEquals(matchStart + 1, matchEnd);
                         // and the offsets must be correct...
                         assertEquals(1, term.Length);
                         assertEquals((char)term.Bytes[term.Offset], Character.ToLower(content[matchStart], CultureInfo.InvariantCulture));
                     }
                     // record just the start/end offset for simplicity
                     seen.Add(new Pair(p.StartOffset, p.EndOffset));
                 }
                 return "bogus!!!!!!";
             }
         }

         internal class Pair
         {
             internal readonly int start;
             internal readonly int end;

             internal Pair(int start, int end)
             {
                 this.start = start;
                 this.end = end;
             }

             public override int GetHashCode()
             {
                 int prime = 31;
                 int result = 1;
                 result = prime * result + end;
                 result = prime * result + start;
                 return result;
             }

             public override bool Equals(object obj)
             {
                 if (this == obj)
                 {
                     return true;
                 }
                 if (obj == null)
                 {
                     return false;
                 }
                 if (GetType() != obj.GetType())
                 {
                     return false;
                 }
                 Pair other = (Pair)obj;
                 if (end != other.end)
                 {
                     return false;
                 }
                 if (start != other.start)
                 {
                     return false;
                 }
                 return true;
             }


             public override string ToString()
             {
                 return "Pair [start=" + start + ", end=" + end + "]";
             }
         }

         /** sets b=0 to disable passage length normalization */
         [Test]
         public void TestCustomB()
         {
             Directory dir = NewDirectory();
             IndexWriterConfig iwc = NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random, MockTokenizer.SIMPLE, true));
             iwc.SetMergePolicy(NewLogMergePolicy());
             RandomIndexWriter iw = new RandomIndexWriter(Random, dir, iwc);

             FieldType offsetsType = new FieldType(TextField.TYPE_STORED);
             offsetsType.IndexOptions = (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
             Field body = new Field("body", "", offsetsType);
             Document doc = new Document();
             doc.Add(body);

             body.SetStringValue("This is a test.  This test is a better test but the sentence is excruiatingly long, " +
                                 "you have no idea how painful it was for me to type this long sentence into my IDE.");
             iw.AddDocument(doc);

             IndexReader ir = iw.GetReader();
             iw.Dispose();

             IndexSearcher searcher = NewSearcher(ir);
             PostingsHighlighter highlighter = new CustomBPostingsHighlighter();
             Query query = new TermQuery(new Term("body", "test"));
             TopDocs topDocs = searcher.Search(query, null, 10, Sort.INDEXORDER);
             assertEquals(1, topDocs.TotalHits);
             String[] snippets = highlighter.Highlight("body", query, searcher, topDocs, 1);
             assertEquals(1, snippets.Length);
             assertTrue(snippets[0].StartsWith("This <b>test</b> is a better <b>test</b>", StringComparison.Ordinal));

             ir.Dispose();
             dir.Dispose();
         }

         internal class CustomBPostingsHighlighter : PostingsHighlighter
         {
             protected override PassageScorer GetScorer(string field)
             {
                 return new PassageScorer(1.2f, 0, 87);
             }
         }

         /** sets k1=0 for simple coordinate-level match (# of query terms present) */
         [Test]
         public void TestCustomK1()
         {
             Directory dir = NewDirectory();
             IndexWriterConfig iwc = NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random, MockTokenizer.SIMPLE, true));
             iwc.SetMergePolicy(NewLogMergePolicy());
             RandomIndexWriter iw = new RandomIndexWriter(Random, dir, iwc);

             FieldType offsetsType = new FieldType(TextField.TYPE_STORED);
             offsetsType.IndexOptions = (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
             Field body = new Field("body", "", offsetsType);
             Document doc = new Document();
             doc.Add(body);

             body.SetStringValue("This has only foo foo. " +
                                 "On the other hand this sentence contains both foo and bar. " +
                                 "This has only bar bar bar bar bar bar bar bar bar bar bar bar.");
             iw.AddDocument(doc);

             IndexReader ir = iw.GetReader();
             iw.Dispose();

             IndexSearcher searcher = NewSearcher(ir);
             PostingsHighlighter highlighter = new CustomK1PostingsHighlighter();
             BooleanQuery query = new BooleanQuery();
             query.Add(new TermQuery(new Term("body", "foo")), Occur.SHOULD);
             query.Add(new TermQuery(new Term("body", "bar")), Occur.SHOULD);
             TopDocs topDocs = searcher.Search(query, null, 10, Sort.INDEXORDER);
             assertEquals(1, topDocs.TotalHits);
             String[] snippets = highlighter.Highlight("body", query, searcher, topDocs, 1);
             assertEquals(1, snippets.Length);
             assertTrue(snippets[0].StartsWith("On the other hand", StringComparison.Ordinal));

             ir.Dispose();
             dir.Dispose();
         }

         internal class CustomK1PostingsHighlighter : PostingsHighlighter
         {
             public CustomK1PostingsHighlighter()
                 : base(10000)
             { }

             protected override PassageScorer GetScorer(string field)
             {
                 return new PassageScorer(0, 0.75f, 87);
             }
         }
     }
 }
 #endif
	#if FEATURE_BREAKITERATOR
	using J2N;
	using Lucene.Net.Analysis;
	using Lucene.Net.Documents;
	using Lucene.Net.Index;
	using Lucene.Net.Index.Extensions;
	using Lucene.Net.Store;
	using Lucene.Net.Util;
	using NUnit.Framework;
	using System;
	using System.Collections.Generic;
	using System.Globalization;
	using System.Text;
	using JCG = J2N.Collections.Generic;

	namespace Lucene.Net.Search.PostingsHighlight
	{
	/*
	* 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.
	*/

	/// <summary>
	/// LUCENENET specific - These are the original tests from Lucene. They are only here as proof that we
	/// can customize the <see cref="ICUPostingsHighlighter"/> to act like the PostingsHighlighter in Lucene,
	/// which has slightly different default behavior than that of ICU because Lucene uses
	/// the RuleBasedBreakIterator from the JDK, not that of ICU4J.
	/// <para/>
	/// These tests use a mock <see cref="PostingsHighlighter"/>, which is backed by an ICU
	/// <see cref="ICU4N.Text.RuleBasedBreakIterator"/> that is customized a bit to act (sort of)
	/// like the one in the JDK. However, this customized implementation is not a logical default for
	/// the <see cref="ICUPostingsHighlighter"/>.
	/// </summary>
	[SuppressCodecs("MockFixedIntBlock", "MockVariableIntBlock", "MockSep", "MockRandom", "Lucene3x")]
	public class TestPostingsHighlighterRanking : LuceneTestCase
	{
	/// <summary>
	/// indexes a bunch of gibberish, and then highlights top(n).
	/// asserts that top(n) highlights is a subset of top(n+1) up to some max N
	/// </summary>
	// TODO: this only tests single-valued fields. we should also index multiple values per field!
	[Test]
	[Slow]
	public void TestRanking()
	{
	// number of documents: we will check each one
	int numDocs = AtLeast(100);
	// number of top-N snippets, we will check 1 .. N
	int maxTopN = 5;
	// maximum number of elements to put in a sentence.
	int maxSentenceLength = 10;
	// maximum number of sentences in a document
	int maxNumSentences = 20;

	Directory dir = NewDirectory();
	RandomIndexWriter iw = new RandomIndexWriter(
	#if FEATURE_INSTANCE_TESTDATA_INITIALIZATION
	this,
	#endif
	Random, dir, new MockAnalyzer(Random, MockTokenizer.SIMPLE, true));
	Document document = new Document();
	Field id = new StringField("id", "", Field.Store.NO);
	FieldType offsetsType = new FieldType(TextField.TYPE_STORED);
	offsetsType.IndexOptions = (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
	Field body = new Field("body", "", offsetsType);
	document.Add(id);
	document.Add(body);

	for (int i = 0; i < numDocs; i++)
	{
	StringBuilder bodyText = new StringBuilder();
	int numSentences = TestUtil.NextInt32(Random, 1, maxNumSentences);
	for (int j = 0; j < numSentences; j++)
	{
	bodyText.Append(newSentence(Random, maxSentenceLength));
	}
	body.SetStringValue(bodyText.ToString());
	id.SetStringValue(i.ToString(CultureInfo.InvariantCulture));
	iw.AddDocument(document);
	}

	IndexReader ir = iw.GetReader();
	IndexSearcher searcher = NewSearcher(ir);
	for (int i = 0; i < numDocs; i++)
	{
	checkDocument(searcher, i, maxTopN);
	}
	iw.Dispose();
	ir.Dispose();
	dir.Dispose();
	}

	private void checkDocument(IndexSearcher @is, int doc, int maxTopN)
	{
	for (int ch = 'a'; ch <= 'z'; ch++)
	{
	Term term = new Term("body", "" + (char)ch);
	// check a simple term query
	checkQuery(@is, new TermQuery(term), doc, maxTopN);
	// check a boolean query
	BooleanQuery bq = new BooleanQuery();
	bq.Add(new TermQuery(term), Occur.SHOULD);
	Term nextTerm = new Term("body", "" + (char)(ch + 1));
	bq.Add(new TermQuery(nextTerm), Occur.SHOULD);
	checkQuery(@is, bq, doc, maxTopN);
	}
	}

	internal class CheckQueryPostingsHighlighter : PostingsHighlighter
	{
	internal FakePassageFormatter f = new FakePassageFormatter();

	public CheckQueryPostingsHighlighter(int maxLength)
	: base(maxLength)
	{
	}

	protected override PassageFormatter GetFormatter(string field)
	{
	assertEquals("body", field);
	return f;
	}
	}

	private void checkQuery(IndexSearcher @is, Query query, int doc, int maxTopN)
	{
	for (int n = 1; n < maxTopN; n++)
	{
	CheckQueryPostingsHighlighter p1 = new CheckQueryPostingsHighlighter(int.MaxValue - 1);
	CheckQueryPostingsHighlighter p2 = new CheckQueryPostingsHighlighter(int.MaxValue - 1);

	BooleanQuery bq = new BooleanQuery(false);
	bq.Add(query, Occur.MUST);
	bq.Add(new TermQuery(new Term("id", doc.ToString(CultureInfo.InvariantCulture))), Occur.MUST);
	TopDocs td = @is.Search(bq, 1);
	p1.Highlight("body", bq, @is, td, n);
	p2.Highlight("body", bq, @is, td, n + 1);
	assertTrue(p2.f.seen.containsAll(p1.f.seen));
	}
	}

	/**
	* returns a new random sentence, up to maxSentenceLength "words" in length.
	* each word is a single character (a-z). The first one is capitalized.
	*/
	private String newSentence(Random r, int maxSentenceLength)
	{
	StringBuilder sb = new StringBuilder();
	int numElements = TestUtil.NextInt32(r, 1, maxSentenceLength);
	for (int i = 0; i < numElements; i++)
	{
	if (sb.Length > 0)
	{
	sb.append(' ');
	sb.append((char)TestUtil.NextInt32(r, 'a', 'z'));
	}
	else
	{
	// capitalize the first word to help breakiterator
	sb.append((char)TestUtil.NextInt32(r, 'A', 'Z'));
	}
	}
	sb.append(". "); // finalize sentence
	return sb.toString();
	}

	/**
	* a fake formatter that doesn't actually format passages.
	* instead it just collects them for asserts!
	*/
	internal class FakePassageFormatter : PassageFormatter
	{
	internal ISet<Pair> seen = new JCG.HashSet<Pair>();

	public override object Format(Passage[] passages, String content)
	{
	foreach (Passage p in passages)
	{
	// verify some basics about the passage
	assertTrue(p.Score >= 0);
	assertTrue(p.NumMatches > 0);
	assertTrue(p.StartOffset >= 0);
	assertTrue(p.StartOffset <= content.Length);
	assertTrue(p.EndOffset >= p.StartOffset);
	assertTrue(p.EndOffset <= content.Length);
	// we use a very simple analyzer. so we can assert the matches are correct
	int lastMatchStart = -1;
	for (int i = 0; i < p.NumMatches; i++)
	{
	BytesRef term = p.MatchTerms[i];
	int matchStart = p.MatchStarts[i];
	assertTrue(matchStart >= 0);
	// must at least start within the passage
	assertTrue(matchStart < p.EndOffset);
	int matchEnd = p.MatchEnds[i];
	assertTrue(matchEnd >= 0);
	// always moving forward
	assertTrue(matchStart >= lastMatchStart);
	lastMatchStart = matchStart;
	// single character terms
	assertEquals(matchStart + 1, matchEnd);
	// and the offsets must be correct...
	assertEquals(1, term.Length);
	assertEquals((char)term.Bytes[term.Offset], Character.ToLower(content[matchStart], CultureInfo.InvariantCulture));
	}
	// record just the start/end offset for simplicity
	seen.Add(new Pair(p.StartOffset, p.EndOffset));
	}
	return "bogus!!!!!!";
	}
	}

	internal class Pair
	{
	internal readonly int start;
	internal readonly int end;

	internal Pair(int start, int end)
	{
	this.start = start;
	this.end = end;
	}

	public override int GetHashCode()
	{
	int prime = 31;
	int result = 1;
	result = prime * result + end;
	result = prime * result + start;
	return result;
	}

	public override bool Equals(object obj)
	{
	if (this == obj)
	{
	return true;
	}
	if (obj == null)
	{
	return false;
	}
	if (GetType() != obj.GetType())
	{
	return false;
	}
	Pair other = (Pair)obj;
	if (end != other.end)
	{
	return false;
	}
	if (start != other.start)
	{
	return false;
	}
	return true;
	}


	public override string ToString()
	{
	return "Pair [start=" + start + ", end=" + end + "]";
	}
	}

	/** sets b=0 to disable passage length normalization */
	[Test]
	public void TestCustomB()
	{
	Directory dir = NewDirectory();
	IndexWriterConfig iwc = NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random, MockTokenizer.SIMPLE, true));
	iwc.SetMergePolicy(NewLogMergePolicy());
	RandomIndexWriter iw = new RandomIndexWriter(Random, dir, iwc);

	FieldType offsetsType = new FieldType(TextField.TYPE_STORED);
	offsetsType.IndexOptions = (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
	Field body = new Field("body", "", offsetsType);
	Document doc = new Document();
	doc.Add(body);

	body.SetStringValue("This is a test. This test is a better test but the sentence is excruiatingly long, " +
	"you have no idea how painful it was for me to type this long sentence into my IDE.");
	iw.AddDocument(doc);

	IndexReader ir = iw.GetReader();
	iw.Dispose();

	IndexSearcher searcher = NewSearcher(ir);
	PostingsHighlighter highlighter = new CustomBPostingsHighlighter();
	Query query = new TermQuery(new Term("body", "test"));
	TopDocs topDocs = searcher.Search(query, null, 10, Sort.INDEXORDER);
	assertEquals(1, topDocs.TotalHits);
	String[] snippets = highlighter.Highlight("body", query, searcher, topDocs, 1);
	assertEquals(1, snippets.Length);
	assertTrue(snippets[0].StartsWith("This <b>test</b> is a better <b>test</b>", StringComparison.Ordinal));

	ir.Dispose();
	dir.Dispose();
	}

	internal class CustomBPostingsHighlighter : PostingsHighlighter
	{
	protected override PassageScorer GetScorer(string field)
	{
	return new PassageScorer(1.2f, 0, 87);
	}
	}

	/** sets k1=0 for simple coordinate-level match (# of query terms present) */
	[Test]
	public void TestCustomK1()
	{
	Directory dir = NewDirectory();
	IndexWriterConfig iwc = NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random, MockTokenizer.SIMPLE, true));
	iwc.SetMergePolicy(NewLogMergePolicy());
	RandomIndexWriter iw = new RandomIndexWriter(Random, dir, iwc);

	FieldType offsetsType = new FieldType(TextField.TYPE_STORED);
	offsetsType.IndexOptions = (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
	Field body = new Field("body", "", offsetsType);
	Document doc = new Document();
	doc.Add(body);

	body.SetStringValue("This has only foo foo. " +
	"On the other hand this sentence contains both foo and bar. " +
	"This has only bar bar bar bar bar bar bar bar bar bar bar bar.");
	iw.AddDocument(doc);

	IndexReader ir = iw.GetReader();
	iw.Dispose();

	IndexSearcher searcher = NewSearcher(ir);
	PostingsHighlighter highlighter = new CustomK1PostingsHighlighter();
	BooleanQuery query = new BooleanQuery();
	query.Add(new TermQuery(new Term("body", "foo")), Occur.SHOULD);
	query.Add(new TermQuery(new Term("body", "bar")), Occur.SHOULD);
	TopDocs topDocs = searcher.Search(query, null, 10, Sort.INDEXORDER);
	assertEquals(1, topDocs.TotalHits);
	String[] snippets = highlighter.Highlight("body", query, searcher, topDocs, 1);
	assertEquals(1, snippets.Length);
	assertTrue(snippets[0].StartsWith("On the other hand", StringComparison.Ordinal));

	ir.Dispose();
	dir.Dispose();
	}

	internal class CustomK1PostingsHighlighter : PostingsHighlighter
	{
	public CustomK1PostingsHighlighter()
	: base(10000)
	{ }

	protected override PassageScorer GetScorer(string field)
	{
	return new PassageScorer(0, 0.75f, 87);
	}
	}
	}
	}
	#endif