Moving backend specific behavior from Page to Iterator.

This is to lower the burden on implementers. The previous
approach (requiring a Page and Iterator subclass) ended
up causing lots of copy-pasta docstrings that were just
a distraction.

Follow up to #2531.

Author: dhermes

packages/google-cloud-resource-manager/google/cloud/resource_manager/client.py

@@ -17,7 +17,6 @@
 
 from google.cloud.client import Client as BaseClient
 from google.cloud.iterator import Iterator
-from google.cloud.iterator import Page
 from google.cloud.resource_manager.connection import Connection
 from google.cloud.resource_manager.project import Project
 
@@ -159,30 +158,6 @@ def list_projects(self, filter_params=None, page_size=None):
         return _ProjectIterator(self, extra_params=extra_params)
 
 
-class _ProjectPage(Page):
-    """Iterator for a single page of results.
-
-    :type parent: :class:`_ProjectIterator`
-    :param parent: The iterator that owns the current page.
-
-    :type response: dict
-    :param response: The JSON API response for a page of projects.
-    """
-
-    ITEMS_KEY = 'projects'
-
-    def _item_to_value(self, resource):
-        """Convert a JSON project to the native object.
-
-        :type resource: dict
-        :param resource: An resource to be converted to a project.
-
-        :rtype: :class:`.Project`
-        :returns: The next project in the page.
-        """
-        return Project.from_api_repr(resource, client=self._parent.client)
-
-
 class _ProjectIterator(Iterator):
     """An iterator over a list of Project resources.
 
@@ -204,5 +179,16 @@ class _ProjectIterator(Iterator):
                          the API call.
     """
 
-    PAGE_CLASS = _ProjectPage
     PATH = '/projects'
+    ITEMS_KEY = 'projects'
+
+    def _item_to_value(self, resource):
+        """Convert a JSON project to the native object.
+
+        :type resource: dict
+        :param resource: An resource to be converted to a project.
+
+        :rtype: :class:`.Project`
+        :returns: The next project in the page.
+        """
+        return Project.from_api_repr(resource, client=self.client)

packages/google-cloud-resource-manager/unit_tests/test_client.py

@@ -15,27 +15,36 @@
 import unittest
 
 
-class Test__ProjectPage(unittest.TestCase):
+class Test__ProjectIterator(unittest.TestCase):
 
     def _getTargetClass(self):
-        from google.cloud.resource_manager.client import _ProjectPage
-        return _ProjectPage
+        from google.cloud.resource_manager.client import _ProjectIterator
+        return _ProjectIterator
 
     def _makeOne(self, *args, **kw):
         return self._getTargetClass()(*args, **kw)
 
-    def test_empty_response(self):
-        from google.cloud.resource_manager.client import _ProjectIterator
+    def test_constructor(self):
+        client = object()
+        iterator = self._makeOne(client)
+        self.assertEqual(iterator.path, '/projects')
+        self.assertEqual(iterator.page_number, 0)
+        self.assertIsNone(iterator.next_page_token)
+        self.assertIs(iterator.client, client)
+        self.assertEqual(iterator.extra_params, {})
+
+    def test_page_empty_response(self):
+        from google.cloud.iterator import Page
 
         client = object()
-        iterator = _ProjectIterator(client)
-        page = self._makeOne(iterator, {})
+        iterator = self._makeOne(client)
+        page = Page(iterator, {}, iterator.ITEMS_KEY)
+        iterator._page = page
         self.assertEqual(page.num_items, 0)
         self.assertEqual(page.remaining, 0)
         self.assertEqual(list(page), [])
 
-    def test_non_empty_response(self):
-        from google.cloud.resource_manager.client import _ProjectIterator
+    def test_page_non_empty_response(self):
         from google.cloud.resource_manager.project import Project
 
         project_id = 'project-id'
@@ -51,13 +60,17 @@ def test_non_empty_response(self):
             'lifecycleState': project_lifecycle_state,
         }
         response = {'projects': [api_resource]}
-
         client = object()
-        iterator = _ProjectIterator(client)
-        page = self._makeOne(iterator, response)
 
+        def dummy_response():
+            return response
+
+        iterator = self._makeOne(client)
+        iterator._get_next_page_response = dummy_response
+
+        page = iterator.page
         self.assertEqual(page.num_items, 1)
-        project = page.next()
+        project = iterator.next()
         self.assertEqual(page.remaining, 0)
         self.assertIsInstance(project, Project)
         self.assertEqual(project.project_id, project_id)
@@ -68,25 +81,6 @@ def test_non_empty_response(self):
         self.assertEqual(project.status, project_lifecycle_state)
 
 
-class Test__ProjectIterator(unittest.TestCase):
-
-    def _getTargetClass(self):
-        from google.cloud.resource_manager.client import _ProjectIterator
-        return _ProjectIterator
-
-    def _makeOne(self, *args, **kw):
-        return self._getTargetClass()(*args, **kw)
-
-    def test_constructor(self):
-        client = object()
-        iterator = self._makeOne(client)
-        self.assertEqual(iterator.path, '/projects')
-        self.assertEqual(iterator.page_number, 0)
-        self.assertIsNone(iterator.next_page_token)
-        self.assertIs(iterator.client, client)
-        self.assertEqual(iterator.extra_params, {})
-
-
 class TestClient(unittest.TestCase):
 
     def _getTargetClass(self):