public virtual void TestEmptyStringVsNullStringSort()
{
Directory dir = NewDirectory();
IndexWriter w = new IndexWriter(dir, NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random())));
Document doc = new Document();
doc.Add(NewStringField("f", "", Field.Store.NO));
doc.Add(NewStringField("t", "1", Field.Store.NO));
w.AddDocument(doc);
w.Commit();
doc = new Document();
doc.Add(NewStringField("t", "1", Field.Store.NO));
w.AddDocument(doc);
IndexReader r = DirectoryReader.Open(w, true);
w.Dispose();
IndexSearcher s = NewSearcher(r);
TopDocs hits = s.Search(new TermQuery(new Term("t", "1")), null, 10, new Sort(new SortField("f", SortField.Type_e.STRING)));
Assert.AreEqual(2, hits.TotalHits);
// null sorts first
Assert.AreEqual(1, hits.ScoreDocs[0].Doc);
Assert.AreEqual(0, hits.ScoreDocs[1].Doc);
r.Dispose();
dir.Dispose();
}