assertTrue(thread.contains("exact line"));
        assertTrue(thread.contains("another line"));
        assertFalse(thread.contains("nonexistent"));
    }

    public void test_contains_withTrimming() throws InterruptedException {
        String input = "  trimmed line  \n\tanother\t";
        InputStream is = new ByteArrayInputStream(input.getBytes(StandardCharsets.UTF_8));