assertEquals(2, callbackResults.size());
        assertEquals("callback1", callbackResults.get(0));
        assertEquals("callback2", callbackResults.get(1));
    }

    public void test_run_bufferSizeLimit() throws InterruptedException {
        StringBuilder inputBuilder = new StringBuilder();
        for (int i = 1; i <= 15; i++) {
            inputBuilder.append("line").append(i).append("\n");
        }