Fix #91 (spec_date_to_iso8601)

[dnaudet]

Fix for #91
Added unit tests for spec_date_to_iso8601.
Nominal tests only.
The zone keyword is not tested. I haven't added tests for the error cases either.
I checked that the new tests fail with the previous version of the function.

BTW the function only works if the provided spec dates are in english (Mon, Apr, Aug, Sun, ....). Are we sure this will always be the case?

[PiRK]

I have investigated Jérôme's suggestion of using datetime. It could simplify the function, especially if we expect to add more date formats in the future. Initially I expected SPEC to write a single format.

>>> from datetime import datetime
>>> d = datetime.strptime('Thu Feb 11 09:54:35+0100 2016', '%a %b %d %H:%M:%S%z %Y')
>>> d.isoformat()
'2016-02-11T09:54:35+01:00'
>>> 
>>> d = datetime.strptime('Sat 2015/03/14 03:53:50+0200', '%a %Y/%m/%d %H:%M:%S%z')
>>> d.isoformat()
'2015-03-14T03:53:50+02:00'

Des anyone have any objection to rewriting the entire function?

[dnaudet]

I think this works only if you set the locale.LC_TIME right.

e.g :

d = datetime.strptime('Mo Feb 11 09:54:35 2016', '%a %b %d %H:%M:%S %Y')

doesn't work if the computer's locale is set to german (locale.setlocale(locale.LC_TIME, 'de_DE.UTF-8'))
It expects this :

d = datetime.strptime('Do Feb 11 09:54:35 2016', '%a %b %d %H:%M:%S %Y')