Test case for my answer to http://stackoverflow.com/questions/20567098/lucene-hierarchial-taxonomy-search

SO20567098Test.java

package stackoverflow;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.StringField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.*;
import org.apache.lucene.search.*;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.Version;
import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;


public class SO20567098Test {

    private static final Version version = Version.LUCENE_46;
    private static final Analyzer analyzer = new StandardAnalyzer(version);

    private static final RAMDirectory dir = new RAMDirectory();

    @Before
    public void setUp() throws Exception {

        IndexWriter writer = new IndexWriter(dir, new IndexWriterConfig(version, analyzer));

        Document doc;

        doc = new Document();
        doc.add(new StringField("id", "1", Field.Store.YES));
        doc.add(new TextField("title", "a funny book", Field.Store.YES));
        doc.add(new TextField("authors", "Jean Bon", Field.Store.YES));
        doc.add(new TextField("authors", "Alex Terieur", Field.Store.YES));
        doc.add(new StringField("book_category", "/novel/comedy/new", Field.Store.YES));
        writer.addDocument(doc);

        doc = new Document();
        doc.add(new StringField("id", "2", Field.Store.YES));
        doc.add(new TextField("title", "a dramatic book", Field.Store.YES));
        doc.add(new TextField("authors", "Alex Terieur", Field.Store.YES));
        doc.add(new StringField("book_category", "/novel/drama", Field.Store.YES));
        writer.addDocument(doc);

        doc = new Document();
        doc.add(new StringField("id", "3", Field.Store.YES));
        doc.add(new TextField("title", "a hilarious book", Field.Store.YES));
        doc.add(new TextField("authors", "Marc Assin", Field.Store.YES));
        doc.add(new TextField("authors", "Harry Covert", Field.Store.YES));
        doc.add(new StringField("book_category", "/novel/comedy", Field.Store.YES));
        writer.addDocument(doc);

        doc = new Document();
        doc.add(new StringField("id", "4", Field.Store.YES));
        doc.add(new TextField("title", "a sad story", Field.Store.YES));
        doc.add(new TextField("authors", "Gerard Menvusa", Field.Store.YES));
        doc.add(new TextField("authors", "Alex Terieur", Field.Store.YES));
        doc.add(new StringField("book_category", "/novel/drama", Field.Store.YES));
        writer.addDocument(doc);

        doc = new Document();
        doc.add(new StringField("id", "5", Field.Store.YES));
        doc.add(new TextField("title", "A very sad story", Field.Store.YES));
        doc.add(new TextField("authors", "Gerard Menvusa", Field.Store.YES));
        doc.add(new TextField("authors", "Alain Terieur", Field.Store.YES));
        doc.add(new StringField("book_category", "/novel", Field.Store.YES));
        writer.addDocument(doc);

        writer.close();
    }

    @Test
    public void testSearch() throws Exception {

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

        float directBoost = 1.0F;
        float narrowerBoost = 0.8F;
        float broaderBoost = 0.5F;

        Query directQuery = new TermQuery(new Term("book_category", "/novel/comedy"));
        Query narrowerQuery = new RegexpQuery(new Term("book_category", "/novel/comedy/[^/]+"));
        Query broaderQuery = new TermQuery(new Term("book_category", "/novel"));

        directQuery = new ConstantScoreQuery(directQuery);
        narrowerQuery = new ConstantScoreQuery(narrowerQuery);
        broaderQuery = new ConstantScoreQuery(broaderQuery);

        directQuery.setBoost(directBoost);
        narrowerQuery.setBoost(narrowerBoost);
        broaderQuery.setBoost(broaderBoost);

        DisjunctionMaxQuery query = new DisjunctionMaxQuery(0.0F);
        query.add(directQuery);
        query.add(narrowerQuery);
        query.add(broaderQuery);

        assertEquals("(ConstantScore(/novel/comedy) | ConstantScore(//novel/comedy/[^/]+/)^0.8 | ConstantScore(/novel)^0.5)", query.toString("book_category"));

        TopDocs topDocs = searcher.search(query, 10);

        assertEquals(3, topDocs.totalHits);

        String[] hitIds = new String[]{
                searcher.doc(topDocs.scoreDocs[0].doc).get("id"),
                searcher.doc(topDocs.scoreDocs[1].doc).get("id"),
                searcher.doc(topDocs.scoreDocs[2].doc).get("id")};

        assertArrayEquals(new String[] {"3", "1", "5"}, hitIds);

        float[] scores = new float[]{
                topDocs.scoreDocs[0].score,
                topDocs.scoreDocs[1].score,
                topDocs.scoreDocs[2].score};

        assertArrayEquals(new float[] {directBoost, narrowerBoost, broaderBoost}, scores, 0.00001F);
    }
}