public virtual void TestPrepareCommitNoEmptyCommits()
{
// LUCENE-4972: DTW used to create empty commits even if no changes were made
Directory dir = NewDirectory();
DirectoryTaxonomyWriter taxoWriter = new DirectoryTaxonomyWriter(dir);
taxoWriter.AddCategory(new FacetLabel("a"));
taxoWriter.PrepareCommit();
taxoWriter.Commit();
long gen1 = SegmentInfos.GetLastCommitGeneration(dir);
taxoWriter.PrepareCommit();
taxoWriter.Commit();
long gen2 = SegmentInfos.GetLastCommitGeneration(dir);
Assert.AreEqual(gen1, gen2, "empty commit should not have changed the index");
taxoWriter.Dispose();
dir.Dispose();
}