It explains the relation between timestamp, timetuple and datetime.

test_time.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

'''
It explains the relation between timestamp, timetuple and datetime.

The principles:

1. If you use datetime without tzinfo (i.e., naive datetime), use mktime with .timetuple to get the timestamp.
2. If you use datetime with tzinfo (i.e., aware datetime), use timegm with .utctimetuple to get the timestamp.
3. Don't mix the naive datetime and aware dateime, except you always use local tzinfo for all aware datetimes (then you should follow the principle #1 or #2).
'''

from time import time, localtime, gmtime, mktime
from calendar import timegm
from datetime import datetime

timestamp = time()
local_timetuple = localtime(timestamp)
utc_timetuple = gmtime(timestamp)
# A datetime without tzinfo is a "naive" datetime.
naive_datetime = datetime.fromtimestamp(timestamp)
aware_datetime = None

try:
    from dateutil.tz import tzlocal
except ImportError:
    import sys
    print >> sys.stderr, 'Warning: Need dateutil to test aware datetime.'
else:
    aware_datetime = datetime.fromtimestamp(timestamp, tzlocal())

print '# From timestamp to timetuple'
print
print '## time() -> now timestamp'
print
print timestamp
print
print '## localtime(timestamp) -> local timetuple'
print
print local_timetuple
print
print '## gmtime(timestamp) -> UTC timetuple'
print
print utc_timetuple
print
print

print '# From timetuple to timestamp'
print
print '## mktime(local_timetuple) -> timestamp'
print
print mktime(local_timetuple)
print
print '## timegm(utc_timetuple) -> timestamp'
print
print timegm(utc_timetuple)
print
print

print '# From naive datetime to timestamp'
print
print 'A datetime without tzinfo is a "naive" datetime.'
print
print '## datetime.fromtimestamp(timestamp) -> naive datetime'
print
print naive_datetime
print
print '## .timetuple() -> local timetuple'
print
print naive_datetime.timetuple()
print
print '## mktime(.timetuple()) -> timestamp'
print
print mktime(naive_datetime.timetuple())
print
print '## .utctimetuple() -> still local timetuple, because it is a "naive" datetime.'
print
print naive_datetime.utctimetuple()
print
print '## timegm(.utctimetuple()) -> *wrong* timestamp, because .utctimetuple of a naive datetime returns a local timetuple.'
print
print timegm(naive_datetime.utctimetuple())
print
print

if aware_datetime:
    print '# From aware datetime to timestamp'
    print
    print '## datetime.fromtimestamp(timestamp, tzlocal())'
    print
    print aware_datetime
    print
    print '## .timetuple() -> local timetuple'
    print
    print aware_datetime.timetuple()
    print
    print '## mktime(.timetuple()) -> timestamp'
    print
    print mktime(aware_datetime.timetuple())
    print
    print '## .utctimetuple() -> UTC timetuple'
    print
    print aware_datetime.utctimetuple()
    print
    print '## timegm(.utctimetuple()) -> timestamp'
    print
    print timegm(aware_datetime.utctimetuple())
    print
    print