Split an index based on a Filter.
        private void CheckSplitting(Directory dir, Term splitTerm, int leftCount, int rightCount)
        {
            using (Directory dir1 = NewDirectory())
            {
                using (Directory dir2 = NewDirectory())
                {
                    PKIndexSplitter splitter = new PKIndexSplitter(dir, dir1, dir2, splitTerm,
                                                                   NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random)),
                                                                   NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random)));
                    splitter.Split();

                    using (IndexReader ir1 = DirectoryReader.Open(dir1))
                    {
                        using (IndexReader ir2 = DirectoryReader.Open(dir2))
                        {
                            assertEquals(leftCount, ir1.NumDocs);
                            assertEquals(rightCount, ir2.NumDocs);


                            CheckContents(ir1, "1");
                            CheckContents(ir2, "2");
                        }
                    }
                }
            }
        }
        private void CheckSplitting(Directory dir, Term splitTerm, int leftCount, int rightCount)
        {
            using (Directory dir1 = NewDirectory())
            {
                using (Directory dir2 = NewDirectory())
                {
                    PKIndexSplitter splitter = new PKIndexSplitter(dir, dir1, dir2, splitTerm,
                        NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random())),
                        NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random())));
                    splitter.Split();

                    using (IndexReader ir1 = DirectoryReader.Open(dir1))
                    {
                        using (IndexReader ir2 = DirectoryReader.Open(dir2))
                        {
                            assertEquals(leftCount, ir1.NumDocs);
                            assertEquals(rightCount, ir2.NumDocs);


                            CheckContents(ir1, "1");
                            CheckContents(ir2, "2");

                        }
                    }
                }
            }
        }