After pallets/werkzeug#1577, mismatched configured and real server
names will show a warning in addition to raising 404. This caused
tests that did this deliberately to fail.
This patch removes the pytest fixture we were using to fail on
warnings, instead using the standard `-Werror` option. This speeds
up the tests by ~3x.
* add fixtures to conftest.py
* use fixtures in test_appctx.py
* use fixtures in test_blueprints.py
* use fixtures in test_depreciations.py
* use fixtures in test_regressions.py
* use fixtures in test_reqctx.py
* use fixtures in test_templating.py
* use fixtures in test_user_error_handler.py
* use fixtures in test_views.py
* use fixtures in test_basics.py
* use fixtures in test_helpers.py
* use fixtures in test_testing.py
* update conftest.py
* make docstrings PEP-257 compliant
* cleanup
* switch dictonary format
* use pytest parameterization for test_json_as_unicode
When an exception has been handled when using the request / app context in a with statement, `sys.exc_info()` will still contain the exception information even though it has been handled already. The `__exit__` methods pass in `None` for the exception value in that case, which needs to be distinguisable from the default value for the `exc` parameter. Use a dedicated singleton sentinel value instead.
