Add a --limit parameter to list operations

In v2, we use the link header during paginations to know when there are
more images available in the server that could be returned in the same
request. This way, it's possible to iterate over the generator returned
by list and consume the images in the server.

However, it's currently not possible to tell glanceclient the exact
number of images we want, which basically means that it'll *always* go
through the whole list of images in the server unless the limit is
implemented by the consumer.

DocImpact
Change-Id: I9f65a40d4eafda6320e5c7d94d03fcd1bbc93e33
Closes-bug: #1415035

tests/v2/test_images.py

@@ -78,6 +78,25 @@ data_fixtures = {
             ]},
         ),
     },
+    '/v2/images?limit=2': {
+        'GET': (
+            {},
+            {
+                'images': [
+                    {
+                        'id': '3a4560a1-e585-443e-9b39-553b46ec92d1',
+                        'name': 'image-1',
+                    },
+                    {
+                        'id': '6f99bf80-2ee6-47cf-acfe-1f1fabb7e810',
+                        'name': 'image-2',
+                    },
+                ],
+                'next': ('/v2/images?limit=2&'
+                         'marker=6f99bf80-2ee6-47cf-acfe-1f1fabb7e810'),
+            },
+        ),
+    },
     '/v2/images?limit=1': {
         'GET': (
             {},
@@ -104,6 +123,17 @@ data_fixtures = {
             ]},
         ),
     },
+    ('/v2/images?limit=1&marker=6f99bf80-2ee6-47cf-acfe-1f1fabb7e810'): {
+        'GET': (
+            {},
+            {'images': [
+                {
+                    'id': '3f99bf80-2ee6-47cf-acfe-1f1fabb7e811',
+                    'name': 'image-3',
+                },
+            ]},
+        ),
+    },
     '/v2/images/3a4560a1-e585-443e-9b39-553b46ec92d1': {
         'GET': (
             {},
@@ -420,6 +450,17 @@ class TestController(testtools.TestCase):
         self.assertEqual('6f99bf80-2ee6-47cf-acfe-1f1fabb7e810', images[1].id)
         self.assertEqual('image-2', images[1].name)
 
+    def test_list_images_paginated_with_limit(self):
+        # NOTE(bcwaldon):cast to list since the controller returns a generator
+        images = list(self.controller.list(limit=3, page_size=2))
+        self.assertEqual('3a4560a1-e585-443e-9b39-553b46ec92d1', images[0].id)
+        self.assertEqual('image-1', images[0].name)
+        self.assertEqual('6f99bf80-2ee6-47cf-acfe-1f1fabb7e810', images[1].id)
+        self.assertEqual('image-2', images[1].name)
+        self.assertEqual('3f99bf80-2ee6-47cf-acfe-1f1fabb7e811', images[2].id)
+        self.assertEqual('image-3', images[2].name)
+        self.assertEqual(3, len(images))
+
     def test_list_images_visibility_public(self):
         filters = {'filters': {'visibility': 'public'}}
         images = list(self.controller.list(**filters))

tests/v2/test_shell_v2.py

@@ -61,6 +61,7 @@ class ShellV2Test(testtools.TestCase):
 
     def test_do_image_list(self):
         input = {
+            'limit': None,
             'page_size': 18,
             'visibility': True,
             'member_status': 'Fake',
@@ -88,6 +89,7 @@ class ShellV2Test(testtools.TestCase):
 
     def test_do_image_list_with_property_filter(self):
         input = {
+            'limit': None,
             'page_size': 1,
             'visibility': True,
             'member_status': 'Fake',