diff --git a/django/contrib/sitemaps/__init__.py b/django/contrib/sitemaps/__init__.py
index 8d779ca2bd..5721c8861d 100644
--- a/django/contrib/sitemaps/__init__.py
+++ b/django/contrib/sitemaps/__init__.py
@@ -21,6 +21,15 @@ def ping_google(sitemap_url=None, ping_url=PING_URL):
     for this site -- e.g., '/sitemap.xml'. If sitemap_url is not provided, this
     function will attempt to deduce it by using urls.reverse().
     """
+    sitemap_full_url = _get_sitemap_full_url(sitemap_url)
+    params = urlencode({'sitemap': sitemap_full_url})
+    urlopen('%s?%s' % (ping_url, params))
+
+
+def _get_sitemap_full_url(sitemap_url):
+    if not django_apps.is_installed('django.contrib.sites'):
+        raise ImproperlyConfigured("ping_google requires django.contrib.sites, which isn't installed.")
+
     if sitemap_url is None:
         try:
             # First, try to get the "index" sitemap URL.
@@ -35,13 +44,9 @@ def ping_google(sitemap_url=None, ping_url=PING_URL):
     if sitemap_url is None:
         raise SitemapNotFound("You didn't provide a sitemap_url, and the sitemap URL couldn't be auto-detected.")
 
-    if not django_apps.is_installed('django.contrib.sites'):
-        raise ImproperlyConfigured("ping_google requires django.contrib.sites, which isn't installed.")
     Site = django_apps.get_model('sites.Site')
     current_site = Site.objects.get_current()
-    url = "http://%s%s" % (current_site.domain, sitemap_url)
-    params = urlencode({'sitemap': url})
-    urlopen("%s?%s" % (ping_url, params))
+    return 'http://%s%s' % (current_site.domain, sitemap_url)
 
 
 class Sitemap(object):
diff --git a/tests/sitemaps_tests/test_management.py b/tests/sitemaps_tests/test_management.py
new file mode 100644
index 0000000000..459a1d1b3c
--- /dev/null
+++ b/tests/sitemaps_tests/test_management.py
@@ -0,0 +1,16 @@
+from django.core.management import call_command
+from django.test import mock
+
+from .base import SitemapTestsBase
+
+
+@mock.patch('django.contrib.sitemaps.management.commands.ping_google.ping_google')
+class PingGoogleTests(SitemapTestsBase):
+
+    def test_default(self, ping_google_func):
+        call_command('ping_google')
+        ping_google_func.assert_called_with(sitemap_url=None)
+
+    def test_arg(self, ping_google_func):
+        call_command('ping_google', 'foo.xml')
+        ping_google_func.assert_called_with(sitemap_url='foo.xml')
diff --git a/tests/sitemaps_tests/test_utils.py b/tests/sitemaps_tests/test_utils.py
new file mode 100644
index 0000000000..ba1eadd5d1
--- /dev/null
+++ b/tests/sitemaps_tests/test_utils.py
@@ -0,0 +1,40 @@
+from django.contrib.sitemaps import (
+    SitemapNotFound, _get_sitemap_full_url, ping_google,
+)
+from django.core.exceptions import ImproperlyConfigured
+from django.test import mock, modify_settings, override_settings
+from django.utils.six.moves.urllib.parse import urlencode
+
+from .base import SitemapTestsBase
+
+
+class PingGoogleTests(SitemapTestsBase):
+
+    @mock.patch('django.contrib.sitemaps.urlopen')
+    def test_something(self, urlopen):
+        ping_google()
+        params = urlencode({'sitemap': 'http://example.com/sitemap-without-entries/sitemap.xml'})
+        full_url = 'https://www.google.com/webmasters/tools/ping?%s' % params
+        urlopen.assert_called_with(full_url)
+
+    def test_get_sitemap_full_url_global(self):
+        self.assertEqual(_get_sitemap_full_url(None), 'http://example.com/sitemap-without-entries/sitemap.xml')
+
+    @override_settings(ROOT_URLCONF='sitemaps_tests.urls.index_only')
+    def test_get_sitemap_full_url_index(self):
+        self.assertEqual(_get_sitemap_full_url(None), 'http://example.com/simple/index.xml')
+
+    @override_settings(ROOT_URLCONF='sitemaps_tests.urls.empty')
+    def test_get_sitemap_full_url_not_detected(self):
+        msg = "You didn't provide a sitemap_url, and the sitemap URL couldn't be auto-detected."
+        with self.assertRaisesMessage(SitemapNotFound, msg):
+            _get_sitemap_full_url(None)
+
+    def test_get_sitemap_full_url_exact_url(self):
+        self.assertEqual(_get_sitemap_full_url('/foo.xml'), 'http://example.com/foo.xml')
+
+    @modify_settings(INSTALLED_APPS={'remove': 'django.contrib.sites'})
+    def test_get_sitemap_full_url_no_sites(self):
+        msg = "ping_google requires django.contrib.sites, which isn't installed."
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            _get_sitemap_full_url(None)
diff --git a/tests/sitemaps_tests/urls/empty.py b/tests/sitemaps_tests/urls/empty.py
new file mode 100644
index 0000000000..637600f58a
--- /dev/null
+++ b/tests/sitemaps_tests/urls/empty.py
@@ -0,0 +1 @@
+urlpatterns = []
diff --git a/tests/sitemaps_tests/urls/index_only.py b/tests/sitemaps_tests/urls/index_only.py
new file mode 100644
index 0000000000..7b9a093d87
--- /dev/null
+++ b/tests/sitemaps_tests/urls/index_only.py
@@ -0,0 +1,9 @@
+from django.conf.urls import url
+from django.contrib.sitemaps import views
+
+from .http import simple_sitemaps
+
+urlpatterns = [
+    url(r'^simple/index\.xml$', views.index, {'sitemaps': simple_sitemaps},
+        name='django.contrib.sitemaps.views.index'),
+]