Add test for endpoint global logic

This didn't make sense to me at first, but for a number of reasons
(noted in the comments) we can't change this behavior just yet.
Otherwise this would be a breaking change to the CLI.  I think there's
probably a better way to do this, but for now leaving things as is.  I
did add a test that documents this behavior though, so hopefully
others don't hit this code and wonder what's going on.

botocore/service.py

@@ -135,6 +135,12 @@ def get_endpoint(self, region_name=None, is_secure=True,
                 # endpoint, we can just use the global_endpoint (which is a
                 # string of the hostname of the global endpoint) to construct
                 # the full endpoint_url.
+                # We have to be careful though.  The "region_name" should have
+                # been previously validated, otherwise it's possible
+                # that we may fail silently if the user provided a region
+                # we don't know about.  For example,
+                # s3.get_endpoint('bad region') would return the global
+                # s3 endpoint, which is probably not what we want.
                 endpoint_url = self._build_endpoint_url(self.global_endpoint,
                                                         is_secure)
                 region_name = 'us-east-1'

tests/unit/test_s3_addressing.py

@@ -19,6 +19,7 @@
 from mock import patch, Mock
 
 import botocore.session
+from botocore.exceptions import ServiceNotInRegionError
 
 
 class TestS3Addressing(BaseSessionTest):
@@ -156,20 +157,45 @@ def test_get_object_non_dns_name_classic(self):
                          'https://s3.amazonaws.com/AnInvalidName/mykeyname')
 
     def test_get_object_ip_address_name_non_classic(self):
-        self.endpoint = self.s3.get_endpoint('us-west-s')
+        self.endpoint = self.s3.get_endpoint('us-west-2')
         op = self.s3.get_operation('GetObject')
         params = op.build_parameters(bucket='192.168.5.4',
                                      key='mykeyname')
         prepared_request = self.get_prepared_request(op, params)
-        self.assertEqual(prepared_request.url,
-                         'https://s3.amazonaws.com/192.168.5.4/mykeyname')
-
+        self.assertEqual(
+            prepared_request.url,
+            'https://s3-us-west-2.amazonaws.com/192.168.5.4/mykeyname')
 
     def test_get_object_almost_an_ip_address_name_non_classic(self):
-        self.endpoint = self.s3.get_endpoint('us-west-s')
+        self.endpoint = self.s3.get_endpoint('us-west-2')
         op = self.s3.get_operation('GetObject')
         params = op.build_parameters(bucket='192.168.5.256',
                                      key='mykeyname')
         prepared_request = self.get_prepared_request(op, params)
-        self.assertEqual(prepared_request.url,
-                         'https://s3.amazonaws.com/192.168.5.256/mykeyname')
+        self.assertEqual(
+            prepared_request.url,
+            'https://s3-us-west-2.amazonaws.com/192.168.5.256/mykeyname')
+
+    def test_non_existent_region(self):
+        # XXX: This is something I think we need to address in the future
+        # but it at least needs to be documented/tested so we know
+        # the current behavior.  If I ask for a region that does not
+        # exist on a global endpoint, such as:
+        endpoint = self.s3.get_endpoint('REGION DOES NOT EXIST')
+        # I get the global endpoint.
+        self.assertEqual(endpoint.region_name, 'us-east-1')
+        # Why not fixed this?  Well backwards compatability for one thing.
+        # The other reason is because it was intended to accomodate this
+        # use case.  Let's say I have us-west-2 set as my default region,
+        # possibly through an env var or config variable.  Well, by default,
+        # we'd make a call like:
+        iam_endpoint = self.session.get_service('iam').get_endpoint('us-west-2')
+        # Instead of giving the user an error, we should instead give
+        # them the global endpoint.
+        self.assertEqual(iam_endpoint.region_name, 'us-east-1')
+        # But if they request an endpoint that we *do* know about, we use
+        # that specific endpoint.
+        self.assertEqual(
+            self.session.get_service('iam').get_endpoint(
+                'us-gov-west-1').region_name,
+            'us-gov-west-1')