public virtual void TestIncompatibleIndexes()
{
// two documents:
Directory dir1 = GetDir1();
// one document only:
Directory dir2 = new MockRAMDirectory();
IndexWriter w2 = new IndexWriter(dir2, new StandardAnalyzer(Util.Version.LUCENE_CURRENT), true, IndexWriter.MaxFieldLength.LIMITED);
Document d3 = new Document();
d3.Add(new Field("f3", "v1", Field.Store.YES, Field.Index.ANALYZED));
w2.AddDocument(d3);
w2.Close();
ParallelReader pr = new ParallelReader();
pr.Add(IndexReader.Open(dir1, false));
Assert.Throws<ArgumentException>(() => pr.Add(IndexReader.Open(dir2, false)),
"didn't get exptected exception: indexes don't have same number of documents");
}