import os
import re
import shutil

def checkOutput(output):
    """
    Ensure hello world is in string.
    return: whether hello world is present
    """
    return output == 'Hello world!\n'

def runCommand(command): 
    """
    Define a function to run a shell commmand and return the output
    param command: command to run
    return: Whether retcode is 0
    """
    fh = os.popen(command, mode='r', buffering=-1)
    output = fh.read()
    retcode = fh.close()
    assert retcode == None


def runCommandAndOutputCheck(command):
    """ 
    Define a function to run a shell command and ensure output is correct
    param command: command
    return: Whether retcode is 0 && output matches test.
    """
    fh = os.popen(command, mode='r', buffering=-1)
    output = fh.read()
    retcode = fh.close()
    assert retcode == None and CheckOutput(output)