pytz test failures with Python 3.8.0a2: PicklingTest.testDatabaseFixes fails

The failing test inspect pickle binary data... I'm not sure of the purpose of the test.

Python 3.8 changed to default pickle protocol from 3 to 4, whereas pytz test is written for pickle protocol 3 (or protocol 0 on Python 2).

The following change fix the test on Python 3.8. I tested my change on Python 2.7, 3.7 and 3.8:

--- pytz/tests/test_tzinfo.py.old 2019-03-14 15:02:49.694890849 +0100
+++ pytz/tests/test_tzinfo.py 2019-03-14 15:09:14.773704193 +0100
@@ -183,8 +183,11 @@
         # Python 3 introduced a new pickle protocol where numbers are stored in
         # hexadecimal representation. Here we extract the pickle
         # representation of the number for the current Python version.
- old_pickle_pattern = pickle.dumps(tz._utcoffset.seconds)[3:-1]
- new_pickle_pattern = pickle.dumps(new_utcoffset)[3:-1]
+ #
+ # Test protocol 3 on Python 3 and protocol 0 on Python 2.
+ protocol = (3 if sys.version_info >= (3,) else 0)
+ old_pickle_pattern = pickle.dumps(tz._utcoffset.seconds, protocol)[3:-1]
+ new_pickle_pattern = pickle.dumps(new_utcoffset, protocol)[3:-1]
         hacked_p = p.replace(old_pickle_pattern, new_pickle_pattern)

         self.assertNotEqual(p, hacked_p)

pytz/tests/test_docs.py also fails on Python 3.8 because repr(datetime.timedelta) changed to include parameter names. Example of failure:

File "pytz/tests/../../README.txt", line 213, in README.txt
Failed example:
    tz.dst(normal)
Expected:
    datetime.timedelta(0, 3600)
Got:
    datetime.timedelta(seconds=3600)

I propose the following fix which should work on all Python versions:

--- README.txt.old 2019-03-14 15:11:54.360631826 +0100
+++ README.txt 2019-03-14 15:13:31.809592925 +0100
@@ -177,29 +177,29 @@
 The ``is_dst`` parameter is ignored for most timestamps. It is only used
 during DST transition ambiguous periods to resolve that ambiguity.

->>> tz.utcoffset(normal, is_dst=True)
-datetime.timedelta(-1, 77400)
->>> tz.dst(normal, is_dst=True)
-datetime.timedelta(0, 3600)
+>>> print(tz.utcoffset(normal, is_dst=True))
+-1 day, 21:30:00
+>>> print(tz.dst(normal, is_dst=True))
+1:00:00
 >>> tz.tzname(normal, is_dst=True)
 'NDT'

->>> tz.utcoffset(ambiguous, is_dst=True)
-datetime.timedelta(-1, 77400)
->>> tz.dst(ambiguous, is_dst=True)
-datetime.timedelta(0, 3600)
+>>> print(tz.utcoffset(ambiguous, is_dst=True))
+-1 day, 21:30:00
+>>> print(tz.dst(ambiguous, is_dst=True))
+1:00:00
 >>> tz.tzname(ambiguous, is_dst=True)
 'NDT'

->>> tz.utcoffset(normal, is_dst=False)
-datetime.timedelta(-1, 77400)
->>> tz.dst(normal, is_dst=False)
-datetime.timedelta(0, 3600)
+>>> print(tz.utcoffset(normal, is_dst=False))
+-1 day, 21:30:00
+>>> print(tz.dst(normal, is_dst=False))
+1:00:00
 >>> tz.tzname(normal, is_dst=False)
 'NDT'

->>> tz.utcoffset(ambiguous, is_dst=False)
-datetime.timedelta(-1, 73800)
+>>> print(tz.utcoffset(ambiguous, is_dst=False))
+-1 day, 20:30:00
 >>> tz.dst(ambiguous, is_dst=False)
 datetime.timedelta(0)
 >>> tz.tzname(ambiguous, is_dst=False)
@@ -208,10 +208,10 @@
 If ``is_dst`` is not specified, ambiguous timestamps will raise
 an ``pytz.exceptions.AmbiguousTimeError`` exception.

->>> tz.utcoffset(normal)
-datetime.timedelta(-1, 77400)
->>> tz.dst(normal)
-datetime.timedelta(0, 3600)
+>>> print(tz.utcoffset(normal))
+-1 day, 21:30:00
+>>> print(tz.dst(normal))
+1:00:00
 >>> tz.tzname(normal)
 'NDT'

First patch, refactored for 2019.1.

The test ensures that an unpickled timestamp references the same instant in time (universal, not wallclock), even if changes to the timezone database have been made since it was pickled.

I've applied Victor's patches, thanks, with syntax adjusted for antique versions of Python.