Mark url method of live_server fixture as deprecated

The `live_server.url` method is not used any more, so mark it as
deprecated. The better way to get live server URL is via `flask.url_for`
function.

Explicitly emit DeprecationWarning when the `live_server.url` is called.

Update test suite to remove any deprecated `live_server.url()` calls.

Author: vitalk

pytest_flask/fixtures.py

@@ -1,9 +1,11 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
-import time
+import functools
 import multiprocessing
 import pytest
 import socket
+import time
+import warnings
 
 try:
     from urllib2 import urlopen
@@ -13,6 +15,21 @@
 from flask import _request_ctx_stack
 
 
+def deprecated(reason):
+    """Decorator which can be used to mark function or method as deprecated.
+    It will result a warning being emmitted when the function is called.
+    """
+    def decorator(func):
+        @functools.wraps(func)
+        def deprecated_call(*args, **kwargs):
+            warnings.simplefilter('always', DeprecationWarning)
+            warnings.warn(reason, DeprecationWarning, stacklevel=2)
+            warnings.simplefilter('default', DeprecationWarning)
+            return func(*args, **kwargs)
+        return deprecated_call
+    return decorator
+
+
 @pytest.yield_fixture
 def client(app):
     """A Flask test client. An instance of :class:`flask.testing.TestClient`
@@ -97,6 +114,11 @@ def _is_ready(self):
             sock.close()
         return ret
 
+    @deprecated(reason=(
+        'The "live_server.url" method is deprecated and scheduled '
+        'to be removed in pytest-flask 1.0.0. Please use '
+        'the "flask.url_for" function instead.',
+    ))
     def url(self, url=''):
         """Returns the complete url based on server options."""
         return 'http://{host!s}:{port!s}{url!s}'.format(

tests/test_live_server.py

@@ -27,8 +27,11 @@ def test_server_url(self, live_server):
         assert live_server.url() == 'http://localhost:%d' % live_server.port
         assert live_server.url('/ping') == 'http://localhost:%d/ping' % live_server.port
 
+    def test_server_url_is_deprecated(self, live_server):
+        assert pytest.deprecated_call(live_server.url)
+
     def test_server_listening(self, live_server):
-        res = urlopen(live_server.url('/ping'))
+        res = urlopen(url_for('ping', _external=True))
         assert res.code == 200
         assert b'pong' in res.read()