Add categories to resource links

Text rendering of OCCI includes the category of the link associated to a
resource. This helps clients to select the links based on their kinds.

Change-Id: Ibd803cb26566e40b5fc589cdea6d111eaec36e03
Closes-Bug: #1656844

ooi/occi/rendering/headers.py

@@ -172,6 +172,10 @@ class LinkRenderer(EntityRenderer):
              "self": url}
         l = '<%(location)s>; rel="%(scheme)s%(term)s"; self="%(self)s"' % d
         ret.append(l)
+        categories = [self.obj.kind.type_id]
+        for m in self.obj.mixins:
+            categories.append(m.type_id)
+        ret.append('category="%s"' % ' '.join(categories))
         for a in self.obj.attributes:
             if self.obj.attributes[a].value is None:
                 continue

ooi/tests/unit/occi/renderings/base.py

@@ -151,3 +151,12 @@ class BaseRendererTest(ooi.tests.base.TestCase):
         r = self.renderer.get_renderer(r1)
         observed = r.render()
         self.assertResourceLink(r1, r2, observed)
+
+    def test_resource_link_with_mixins(self):
+        r1 = resource.Resource(None, [])
+        r2 = resource.Resource(None, [])
+        r1.link(r2, [mixin.Mixin("s1", "term", "title"),
+                     mixin.Mixin("s2", "term", "title")])
+        r = self.renderer.get_renderer(r1)
+        observed = r.render()
+        self.assertResourceLink(r1, r2, observed)

ooi/tests/unit/occi/renderings/test_header.py

@@ -139,12 +139,18 @@ class TestOCCIHeaderRendering(base.BaseRendererTest):
                 self.assertEqual(rel, parsed[1])
                 self_ = 'self="%s"' % link.location
                 self.assertEqual(self_, parsed[2])
+                expected_cats = [link.kind.type_id]
+                expected_cats.extend([m.type_id for m in link.mixins])
+                category_field = parsed[3].split('=')
+                self.assertEqual('category', category_field[0])
+                link_cats = category_field[1][1:-1].split()
+                self.assertItemsEqual(expected_cats, link_cats)
                 source = 'occi.core.source="%s"' % obj1.location
-                self.assertIn(source, parsed[3:])
+                self.assertIn(source, parsed[4:])
                 target = 'occi.core.target="%s"' % obj2.location
-                self.assertIn(target, parsed[3:])
+                self.assertIn(target, parsed[4:])
                 id = 'occi.core.id="%s"' % link.id
-                self.assertIn(id, parsed[3:])
+                self.assertIn(id, parsed[4:])
                 break
         else:
             self.fail("One link was expected")

ooi/tests/unit/occi/renderings/test_json.py

@@ -89,6 +89,8 @@ class TestOCCIJsonRendering(base.BaseRendererTest):
             },
             "title": obj.title,
         }
+        if obj.mixins:
+            link["mixins"] = [m.type_id for m in obj.mixins]
         self.assertEqual(link, json.loads(observed))
 
     def assertMixedCollection(self, kind, resource, observed):