SpanNearQuery returns single term spans [LUCENE-5396]

Let's assume we have an index with two documents:

1. contents: "test bunga bunga test"
2. contents: "test bunga test"

We run two SpanNearQueries against this index:

1. spanNear([contents:bunga, contents:bunga], 0, true)
2. spanNear([contents:bunga, contents:bunga], 0, false)

For the first query we get 1 hit. The first document in the example above gets matched and the second one doesn't. This make sense, because we want the term "bunga" followed by another "bunga" here.

However, both documents get matched by the second query. This is also problematic in cases where we have duplicate terms in longer (unordered) spannear queries, e. g.: unordered 'A B A' will match spans such as 'A B' or 'B A'.

A complete example follows.

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import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.spans.SpanNearQuery;
import org.apache.lucene.search.spans.SpanQuery;
import org.apache.lucene.search.spans.SpanTermQuery;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.Version;
import java.io.StringReader;
import static org.junit.Assert.assertEquals;

class SpansBug {

public static void main(String [] args) throws Exception {

Directory dir = new RAMDirectory();
Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_45);
IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_45, analyzer);

IndexWriter writer = new IndexWriter(dir, iwc);
String contents = "contents";
Document doc1 = new Document();
doc1.add(new TextField(contents, new StringReader("test bunga bunga test")));
Document doc2 = new Document();
doc2.add(new TextField(contents, new StringReader("test bunga test")));

writer.addDocument(doc1);
writer.addDocument(doc2);

writer.commit();

IndexSearcher searcher = new IndexSearcher(DirectoryReader.open(dir));

SpanQuery stq1 = new SpanTermQuery(new Term(contents,"bunga"));
SpanQuery stq2 = new SpanTermQuery(new Term(contents,"bunga"));
SpanQuery [] spqa = new SpanQuery[]{stq1,stq2};

SpanNearQuery spanQ1 = new SpanNearQuery(spqa,0, true);
SpanNearQuery spanQ2 = new SpanNearQuery(spqa,0, false);

System.out.println(spanQ1);

TopDocs tdocs1 = searcher.search(spanQ1,10);
assertEquals(tdocs1.totalHits ,1);

System.out.println(spanQ2);

TopDocs tdocs2 = searcher.search(spanQ2,10);
//I'd expect one hit here:
assertEquals(tdocs2.totalHits ,1); // Assertion fails

}
}

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Migrated from [LUCENE-5396](https://issues.apache.org/jira/browse/LUCENE-5396) by Piotr Pęzik, 1 vote, updated Sep 06 2016

Start with the provided SpanNearQuery example and reproduce the failing assertion using the two documents and unordered duplicate SpanTermQuery clauses. The fix is complete when the unordered query does not match a single-term span and the expected hit count assertion passes.

Written by the indexing model from the issue text.