Use specific asserts in warnings and exceptions tests #64747

assignee = None
closed_at = <Date 2017-03-30.15:07:08.945>
created_at = <Date 2014-02-07.20:26:11.986>
labels = ['3.7', 'easy', 'type-feature', 'tests']
title = 'Use specific asserts in warnings and exceptions tests'
updated_at = <Date 2017-03-30.15:07:08.944>
user = 'https://github.com/serhiy-storchaka'

activity = <Date 2017-03-30.15:07:08.944>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2017-03-30.15:07:08.945>
closer = 'serhiy.storchaka'
components = ['Tests']
creation = <Date 2014-02-07.20:26:11.986>
creator = 'serhiy.storchaka'
dependencies = []
files = ['33973']
hgrepos = []
issue_num = 20548
keywords = ['patch', 'easy']
message_count = 3.0
messages = ['210545', '237321', '290847']
nosy_count = 1.0
nosy_names = ['serhiy.storchaka']
pr_nums = ['788']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue20548'
versions = ['Python 3.7']