I have a bug fix, additional tests for the `limiter` method, and additional commenting for a couple classes in the OpenStack API. Basically I've just tried to jump in somewhere to get my feet wet. Constructive criticism welcome.

3 files changed, 181 insertions, 41 deletions

diff --git a/nova/api/openstack/common.py b/nova/api/openstack/common.py
index 6d2fa16e8..1dc3767e2 100644
--- a/nova/api/openstack/common.py
+++ b/nova/api/openstack/common.py
@@ -18,22 +18,29 @@
 from nova import exception
 
 
-def limited(items, req):
-    """Return a slice of items according to requested offset and limit.
-
-    items - a sliceable
-    req - wobob.Request possibly containing offset and limit GET variables.
-          offset is where to start in the list, and limit is the maximum number
-          of items to return.
+def limited(items, request, max_limit=1000):
+    """
+    Return a slice of items according to requested offset and limit.
 
-    If limit is not specified, 0, or > 1000, defaults to 1000.
+    @param items: A sliceable entity
+    @param request: `webob.Request` possibly containing 'offset' and 'limit'
+                    GET variables. 'offset' is where to start in the list,
+                    and 'limit' is the maximum number of items to return. If
+                    'limit' is not specified, 0, or > max_limit, we default
+                    to max_limit.
+    @kwarg max_limit: The maximum number of items to return from 'items'
     """
+    try:
+        offset = int(request.GET.get('offset', 0))
+    except ValueError:
+        offset = 0
+
+    try:
+        limit = int(request.GET.get('limit', max_limit))
+    except ValueError:
+        limit = max_limit
 
-    offset = int(req.GET.get('offset', 0))
-    limit = int(req.GET.get('limit', 0))
-    if not limit:
-        limit = 1000
-    limit = min(1000, limit)
+    limit = min(max_limit, limit or max_limit)
     range_end = offset + limit
     return items[offset:range_end]
 
diff --git a/nova/tests/api/openstack/__init__.py b/nova/tests/api/openstack/__init__.py
index 14eaaa62c..77b1dd37f 100644
--- a/nova/tests/api/openstack/__init__.py
+++ b/nova/tests/api/openstack/__init__.py
@@ -92,31 +92,3 @@ class RateLimitingMiddlewareTest(unittest.TestCase):
         self.assertEqual(middleware.limiter.__class__.__name__, "Limiter")
         middleware = RateLimitingMiddleware(simple_wsgi, service_host='foobar')
         self.assertEqual(middleware.limiter.__class__.__name__, "WSGIAppProxy")
-
-
-class LimiterTest(unittest.TestCase):
-
-    def test_limiter(self):
-        items = range(2000)
-        req = Request.blank('/')
-        self.assertEqual(limited(items, req), items[:1000])
-        req = Request.blank('/?offset=0')
-        self.assertEqual(limited(items, req), items[:1000])
-        req = Request.blank('/?offset=3')
-        self.assertEqual(limited(items, req), items[3:1003])
-        req = Request.blank('/?offset=2005')
-        self.assertEqual(limited(items, req), [])
-        req = Request.blank('/?limit=10')
-        self.assertEqual(limited(items, req), items[:10])
-        req = Request.blank('/?limit=0')
-        self.assertEqual(limited(items, req), items[:1000])
-        req = Request.blank('/?limit=3000')
-        self.assertEqual(limited(items, req), items[:1000])
-        req = Request.blank('/?offset=1&limit=3')
-        self.assertEqual(limited(items, req), items[1:4])
-        req = Request.blank('/?offset=3&limit=0')
-        self.assertEqual(limited(items, req), items[3:1003])
-        req = Request.blank('/?offset=3&limit=1500')
-        self.assertEqual(limited(items, req), items[3:1003])
-        req = Request.blank('/?offset=3000&limit=10')
-        self.assertEqual(limited(items, req), [])
diff --git a/nova/tests/api/openstack/test_common.py b/nova/tests/api/openstack/test_common.py
new file mode 100644
index 000000000..9d9837cc9
--- /dev/null
+++ b/nova/tests/api/openstack/test_common.py
@@ -0,0 +1,161 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 OpenStack LLC.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""
+Test suites for 'common' code used throughout the OpenStack HTTP API.
+"""
+
+import unittest
+
+from webob import Request
+
+from nova.api.openstack.common import limited
+
+
+class LimiterTest(unittest.TestCase):
+    """
+    Unit tests for the `nova.api.openstack.common.limited` method which takes
+    in a list of items and, depending on the 'offset' and 'limit' GET params,
+    returns a subset or complete set of the given items.
+    """
+
+    def setUp(self):
+        """
+        Run before each test.
+        """
+        self.tiny = range(1)
+        self.small = range(10)
+        self.medium = range(1000)
+        self.large = range(10000)
+
+    def test_limiter_offset_zero(self):
+        """
+        Test offset key works with 0.
+        """
+        req = Request.blank('/?offset=0')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium)
+        self.assertEqual(limited(self.large, req), self.large[:1000])
+
+    def test_limiter_offset_medium(self):
+        """
+        Test offset key works with a medium sized number.
+        """
+        req = Request.blank('/?offset=10')
+        self.assertEqual(limited(self.tiny, req), [])
+        self.assertEqual(limited(self.small, req), self.small[10:])
+        self.assertEqual(limited(self.medium, req), self.medium[10:])
+        self.assertEqual(limited(self.large, req), self.large[10:1010])
+
+    def test_limiter_offset_over_max(self):
+        """
+        Test offset key works with a number over 1000 (max_limit).
+        """
+        req = Request.blank('/?offset=1001')
+        self.assertEqual(limited(self.tiny, req), [])
+        self.assertEqual(limited(self.small, req), [])
+        self.assertEqual(limited(self.medium, req), [])
+        self.assertEqual(limited(self.large, req), self.large[1001:2001])
+
+    def test_limiter_offset_blank(self):
+        """
+        Test offset key works with a blank offset.
+        """
+        req = Request.blank('/?offset=')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium)
+        self.assertEqual(limited(self.large, req), self.large[:1000])
+
+    def test_limiter_offset_bad(self):
+        """
+        Test offset key works with a BAD offset.
+        """
+        req = Request.blank(u'/?offset=\u0020aa')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium)
+        self.assertEqual(limited(self.large, req), self.large[:1000])
+
+    def test_limiter_nothing(self):
+        """
+        Test request with no offset or limit
+        """
+        req = Request.blank('/')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium)
+        self.assertEqual(limited(self.large, req), self.large[:1000])
+
+    def test_limiter_limit_zero(self):
+        """
+        Test limit of zero.
+        """
+        req = Request.blank('/?limit=0')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium)
+        self.assertEqual(limited(self.large, req), self.large[:1000])
+
+    def test_limiter_limit_medium(self):
+        """
+        Test limit of 10.
+        """
+        req = Request.blank('/?limit=10')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium[:10])
+        self.assertEqual(limited(self.large, req), self.large[:10])
+
+    def test_limiter_limit_over_max(self):
+        """
+        Test limit of 3000.
+        """
+        req = Request.blank('/?limit=3000')
+        self.assertEqual(limited(self.tiny, req), self.tiny)
+        self.assertEqual(limited(self.small, req), self.small)
+        self.assertEqual(limited(self.medium, req), self.medium)
+        self.assertEqual(limited(self.large, req), self.large[:1000])
+
+    def test_limiter_limit_and_offset(self):
+        """
+        Test request with both limit and offset.
+        """
+        items = range(2000)
+        req = Request.blank('/?offset=1&limit=3')
+        self.assertEqual(limited(items, req), items[1:4])
+        req = Request.blank('/?offset=3&limit=0')
+        self.assertEqual(limited(items, req), items[3:1003])
+        req = Request.blank('/?offset=3&limit=1500')
+        self.assertEqual(limited(items, req), items[3:1003])
+        req = Request.blank('/?offset=3000&limit=10')
+        self.assertEqual(limited(items, req), [])
+
+    def test_limiter_custom_max_limit(self):
+        """
+        Test a max_limit other than 1000.
+        """
+        items = range(2000)
+        req = Request.blank('/?offset=1&limit=3')
+        self.assertEqual(limited(items, req, max_limit=2000), items[1:4])
+        req = Request.blank('/?offset=3&limit=0')
+        self.assertEqual(limited(items, req, max_limit=2000), items[3:])
+        req = Request.blank('/?offset=3&limit=2500')
+        self.assertEqual(limited(items, req, max_limit=2000), items[3:])
+        req = Request.blank('/?offset=3000&limit=10')
+        self.assertEqual(limited(items, req, max_limit=2000), [])