Vincenty: add deprecation warning (#293)

geopy/distance.py

@@ -473,8 +473,15 @@ class vincenty(Distance):
 
     ellipsoid_key = None
     ELLIPSOID = None
+    _show_deprecation_warning = True
 
     def __init__(self, *args, **kwargs):
+        if self._show_deprecation_warning:
+            warnings.warn('Vincenty is deprecated and is going to be removed '
+                          'in geopy 2.0. Use `geopy.distance.geodesic` '
+                          '(or the default `geopy.distance.distance`) '
+                          'instead, which is more accurate and always converges.',
+                          DeprecationWarning)
         self.set_ellipsoid(kwargs.pop('ellipsoid', 'WGS-84'))
         self.iterations = kwargs.pop('iterations', 20)
         major, minor, f = self.ELLIPSOID # pylint: disable=W0612

test/test_distance.py

@@ -4,6 +4,7 @@
 import math
 import unittest
 import warnings
+from mock import patch
 
 from geopy import distance as geopy_distance
 from geopy.point import Point
@@ -291,6 +292,11 @@ def test_lonlat_function(self):
         point = lonlat(*newport_ri_xy)
         self.assertEqual(point, (41.49008, -71.312796, 0))
 
+    def test_vincenty_deprecation_warning(self):
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('always')
+            VincentyDistance((0, 0), (10, 10))
+            self.assertEqual(1, len(w))
 
 class TestWhenComputingGreatCircleDistance(CommonDistanceCases,
                                            unittest.TestCase):
@@ -307,6 +313,7 @@ def test_should_compute_destination_for_half_trip_around_equator(self):
         self.assertAlmostEqual(destination.longitude, 180)
 
 
+@patch.object(VincentyDistance, '_show_deprecation_warning', False)
 class TestWhenComputingVincentyDistance(CommonDistanceCases,
                                         unittest.TestCase):