import praw
import time
import config

def login():
    r = praw.Reddit(user_agent = "test bot",
                username = config.username,
                password = config.password,
                client_id = config.client_id,
                client_secret = config.client_secret)
    print("logged in")
    return r


cache = []

def run_bot(r):
    subreddit = r.subreddit("Test")
    comments = subreddit.get_comments(limit=25)
    for comment in comments:
        comment_text = comment.body.lower()
        if "xD" in comment_text and comment.id not in cache:
            comment.reply("xD")
            cache.append(comment.id)

while True:
    r = login()
    run_bot(r)
    time.sleep(5)

logged in
Traceback (most recent call last):
  File "xdbot.py", line 28, in <module>
    run_bot(r)
  File "xdbot.py", line 19, in run_bot
    comments = subreddit.get_comments(limit=25)
  File "D:ProgrammingPhytonlibsite-packagesprawmodelsredditbase.py", line 31, in __getattr__
    self._fetch()
  File "D:ProgrammingPhytonlibsite-packagesprawmodelsredditbase.py", line 66, in _fetch
    params=self._info_params)
  File "D:ProgrammingPhytonlibsite-packagesprawreddit.py", line 367, in get
    data = self.request('GET', path, params=params)
  File "D:ProgrammingPhytonlibsite-packagesprawreddit.py", line 451, in request
    params=params)
  File "D:ProgrammingPhytonlibsite-packagesprawcoresessions.py", line 174, in request
    params=params, url=url)
  File "D:ProgrammingPhytonlibsite-packagesprawcoresessions.py", line 108, in _request_with_retries
    data, files, json, method, params, retries, url)
  File "D:ProgrammingPhytonlibsite-packagesprawcoresessions.py", line 93, in _make_request
    params=params)
  File "D:ProgrammingPhytonlibsite-packagesprawcorerate_limit.py", line 32, in call
    kwargs['headers'] = set_header_callback()
  File "D:ProgrammingPhytonlibsite-packagesprawcoresessions.py", line 134, in _set_header_callback
    self._authorizer.refresh()
  File "D:ProgrammingPhytonlibsite-packagesprawcoreauth.py", line 328, in refresh
    password=self._password)
  File "D:ProgrammingPhytonlibsite-packagesprawcoreauth.py", line 142, in _request_token
    payload.get('error_description'))
prawcore.exceptions.OAuthException: invalid_grant error processing request