Lucene.Net.Store.MockDirectoryWrapper.FailOn C# (CSharp) Method

        public virtual void FailOn(Failure fail)
        {
            lock (this)
            {
                if (Failures == null)
                {
                    Failures = new List<Failure>();
                }
                Failures.Add(fail);
            }
        }

        public void TestExceptionOnBackgroundThreadIsPropagatedToCallingThread()
        {
            using (MockDirectoryWrapper dir = NewMockDirectory())
            {
                dir.FailOn(new FailOnlyOnMerge());

                Document doc = new Document();
                Field idField = NewStringField("id", "", Field.Store.YES);
                doc.Add(idField);

                var mergeScheduler = new ConcurrentMergeScheduler();
                using (IndexWriter writer = new IndexWriter(dir, NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random)).SetMergeScheduler(mergeScheduler).SetMaxBufferedDocs(2).SetRAMBufferSizeMB(IndexWriterConfig.DISABLE_AUTO_FLUSH).SetMergePolicy(NewLogMergePolicy())))
                {
                    LogMergePolicy logMP = (LogMergePolicy)writer.Config.MergePolicy;
                    logMP.MergeFactor = 10;
                    for (int i = 0; i < 20; i++)
                    {
                        writer.AddDocument(doc);
                    }

                    bool exceptionHit = false;
                    try
                    {
                        mergeScheduler.Sync();
                    }
                    catch (MergePolicy.MergeException)
                    {
                        exceptionHit = true;
                    }

                    assertTrue(exceptionHit);
                }
            }
        }