String output = thread.getOutput();
        assertTrue(output.contains("line1"));
        assertTrue(output.contains("line2"));
        assertTrue(output.contains("line3"));
    }

    public void test_run_withoutBuffering() throws InterruptedException {
        String input = "line1\nline2";
        InputStream is = new ByteArrayInputStream(input.getBytes(StandardCharsets.UTF_8));