thread.join(1000);

        assertEquals("All lines should be processed", 5000, receivedLines.size());
        assertEquals("First line", "Line number 0", receivedLines.get(0));
        assertEquals("Last line", "Line number 4999", receivedLines.get(4999));
    }

    public void test_run_concurrentAccess() throws InterruptedException {
        String input = "concurrent1\nconcurrent2\nconcurrent3";

        String[] inputs = { "input" };
        CharMappingItem item = new CharMappingItem(1L, inputs, "output");

        // Test newline replacement in setNewOutput
        item.setNewOutput("line1\nline2\nline3");
        assertEquals("line1 line2 line3", item.getNewOutput());
    }

    public void test_setNewOutput_withNull() {
        String[] inputs = { "input" };
        CharMappingItem item = new CharMappingItem(1L, inputs, "output");

 * <p>Several methods in this class, such as {@link #readLines()}, break the contents of the source
 * into lines. Like {@link BufferedReader}, these methods break lines on any of {@code \n}, {@code
 * \r} or {@code \r\n}, do not include the line separator in each line and do not consider there to
 * be an empty line at the end if the contents are terminated with a line separator.
 *

 * <p>Several methods in this class, such as {@link #readLines()}, break the contents of the source
 * into lines. Like {@link BufferedReader}, these methods break lines on any of {@code \n}, {@code
 * \r} or {@code \r\n}, do not include the line separator in each line and do not consider there to
 * be an empty line at the end if the contents are terminated with a line separator.
 *

            // Verify content structure
            boolean hasThreadLine = lines.stream().anyMatch(line -> line.startsWith("Thread:"));
            boolean hasStackTraceLine = lines.stream().anyMatch(line -> line.startsWith("\tat "));

            assertTrue("Should contain thread information", hasThreadLine);
            assertTrue("Should contain stack trace information", hasStackTraceLine);

   * @return a mutable {@link List} containing all the lines
   * @throws IOException if an I/O error occurs
   */
  public static List<String> readLines(Readable r) throws IOException {
    List<String> result = new ArrayList<>();
    LineReader lineReader = new LineReader(r);
    String line;
    while ((line = lineReader.readLine()) != null) {
      result.add(line);
    }
    return result;
  }

  /**

  private fun readJournalLine(line: String) {
    val firstSpace = line.indexOf(' ')
    if (firstSpace == -1) throw IOException("unexpected journal line: $line")

    val keyBegin = firstSpace + 1
    val secondSpace = line.indexOf(' ', keyBegin)
    val key: String
    if (secondSpace == -1) {
      key = line.substring(keyBegin)
      if (firstSpace == REMOVE.length && line.startsWith(REMOVE)) {

     * Captures output from command execution with configurable line buffering.
     */
    protected static class InputStreamThread extends Thread {

        /** Buffered reader for input stream. */
        private BufferedReader br;

        /** List to store captured output lines. */
        private final List<String> list = new LinkedList<>();

        /** Maximum number of lines to buffer. */
        private final int maxLineBuffer;

    TestCharSource lines = new TestCharSource(LINES);
    assertEquals("foo", lines.readFirstLine());
    assertTrue(lines.wasStreamOpened() && lines.wasStreamClosed());
  }

  public void testReadLines_toList() throws IOException {
    TestCharSource lines = new TestCharSource(LINES);
    assertEquals(ImmutableList.of("foo", "bar", "baz", "something"), lines.readLines());

            long id = 0;
            String line = null;
            while ((line = reader.readLine()) != null) {
                // Remove comments
                final String replacedLine = line.replaceAll("#.*$", StringUtil.EMPTY).trim();

                // Skip empty lines or comment lines
                if (replacedLine.length() == 0) {
                    if (updater != null) {