schema: add basic support for choice and case

Let's add enough to parse a model with choices and cases, so that
iter_tree is working. Before this patch, the unit test added by this
patch would fail with:

> ======================================================================
> ERROR: test_iter_tree (test_schema.ContainerTest)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>  File "(...)/libyang-python/tests/test_schema.py", line 278, in test_iter_tree
>    tree = list(self.container.iter_tree())
>  File "(...)/libyang-python/.tox/py3/lib/python3.9/site-packages/libyang/schema.py", line 1148, in iter_tree
>    yield self.new(self.context, n)
>  File "(...)/libyang-python/.tox/py3/lib/python3.9/site-packages/libyang/schema.py", line 1192, in new
>    raise TypeError("node type %s not implemented" % cdata.nodetype)
> TypeError: node type 2 not implemented

Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>
Acked-by: Robin Jarry <robin@jarry.cc>

Author: samuel-gauthier

libyang/schema.py

@@ -878,6 +878,8 @@ class SNode:
     __slots__ = ("context", "cdata", "cdata_parsed", "__dict__")
 
     CONTAINER = lib.LYS_CONTAINER
+    CHOICE = lib.LYS_CHOICE
+    CASE = lib.LYS_CASE
     LEAF = lib.LYS_LEAF
     LEAFLIST = lib.LYS_LEAFLIST
     LIST = lib.LYS_LIST
@@ -1196,6 +1198,26 @@ def children(self, types: Optional[Tuple[int, ...]] = None) -> Iterator[SNode]:
         return iter_children(self.context, self.cdata, types=types)
 
 
+# -------------------------------------------------------------------------------------
+@SNode.register(SNode.CHOICE)
+class SChoice(SNode):
+    def __iter__(self) -> Iterator[SNode]:
+        return self.children()
+
+    def children(self, types: Optional[Tuple[int, ...]] = None) -> Iterator[SNode]:
+        return iter_children(self.context, self.cdata, types=types)
+
+
+# -------------------------------------------------------------------------------------
+@SNode.register(SNode.CASE)
+class SCase(SNode):
+    def __iter__(self) -> Iterator[SNode]:
+        return self.children()
+
+    def children(self, types: Optional[Tuple[int, ...]] = None) -> Iterator[SNode]:
+        return iter_children(self.context, self.cdata, types=types)
+
+
 # -------------------------------------------------------------------------------------
 @SNode.register(SNode.LIST)
 class SList(SNode):

tests/test_diff.py

@@ -81,6 +81,12 @@ class DiffTest(unittest.TestCase):
             (EnumStatusAdded, "/yolo-system:state/url/proto"),
             (EnumStatusRemoved, "/yolo-system:conf/url/proto"),
             (EnumStatusRemoved, "/yolo-system:state/url/proto"),
+            (SNodeAdded, "/yolo-system:conf/pill/red/out"),
+            (SNodeAdded, "/yolo-system:state/pill/red/out"),
+            (SNodeAdded, "/yolo-system:conf/pill/blue/in"),
+            (SNodeAdded, "/yolo-system:state/pill/blue/in"),
+            (SNodeAdded, "/yolo-system:alarm-triggered/severity"),
+            (SNodeAdded, "/yolo-system:alarm-triggered/description"),
         )
     )
 

tests/test_schema.py

@@ -258,20 +258,20 @@ def test_cont_attrs(self):
 
     def test_cont_iter(self):
         children = list(iter(self.container))
-        self.assertEqual(len(children), 9)
+        self.assertEqual(len(children), 11)
 
     def test_cont_children_leafs(self):
         leafs = list(self.container.children(types=(SNode.LEAF,)))
-        self.assertEqual(len(leafs), 7)
+        self.assertEqual(len(leafs), 9)
 
     def test_cont_parent(self):
         self.assertIsNone(self.container.parent())
 
     def test_iter_tree(self):
         tree = list(self.container.iter_tree())
-        self.assertEqual(len(tree), 15)
-        tree = list(self.container.iter_tree(full=True))
         self.assertEqual(len(tree), 20)
+        tree = list(self.container.iter_tree(full=True))
+        self.assertEqual(len(tree), 25)
 
 
 # -------------------------------------------------------------------------------------
@@ -455,3 +455,7 @@ def test_leaf_parent(self):
         self.assertIsNotNone(parent)
         self.assertIsInstance(parent, SList)
         self.assertEqual(parent.name(), "url")
+
+    def test_iter_tree(self):
+        leaf = next(self.ctx.find_path("/yolo-system:conf"))
+        self.assertEqual(len(list(leaf.iter_tree(full=True))), 23)

tests/yang/yolo/yolo-system.yang

@@ -60,6 +60,19 @@ module yolo-system {
       type string;
     }
 
+    choice pill {
+      case red {
+        leaf out {
+          type boolean;
+        }
+      }
+      case blue {
+        leaf in {
+          type boolean;
+        }
+      }
+    }
+
     list url {
       description
         "An URL.";