curds: Implement a node.append_child() function

Sometimes we just want to append a node instead of inserting it in a
sorted position.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

curds/playlist/node.py

@@ -19,16 +19,21 @@ class PlaylistNode:
     def __lt__(self, rhs):
         return self.name < rhs.name
 
+    def append_child(self, child):
+        prev = None
+        if len(self.children) > 0:
+            prev = self.children[-1]
+        self.children.append(child)
+        self.__link_children__(prev, child)
+        return self.children.index(child)
+
     def insert_child(self, child):
-        n = None
         for i, n in enumerate(self.children):
             if child < n:
                 self.children.insert(i, child)
                 self.__link_children__(child, n)
                 return self.children.index(child)
-        self.children.append(child)
-        self.__link_children__(n, child)
-        return self.children.index(child)
+        return self.append_child(child)
 
     def n_children(self):
         return len(self.children)

curds/playlist/test_node.py

@@ -23,6 +23,29 @@ class TestPlaylistNode(unittest.TestCase):
         self.assertFalse(b < a)
         self.assertFalse(a < a)
 
+    def test_node_append_child(self):
+        root = node.PlaylistNode()
+        a = node.PlaylistNode("a")
+        b = node.PlaylistNode("b")
+        c = node.PlaylistNode("c")
+
+        self.assertEqual(root.n_children(),    0)
+        self.assertEqual(root.append_child(b), 0)
+        self.assertEqual(root.n_children(),    1)
+        self.assertEqual(root.children, [ b ])
+
+        self.assertEqual(root.append_child(a), 1)
+        self.assertEqual(root.n_children(),    2)
+        self.assertEqual(root.children, [ b, a ])
+        self.assertEqual(b.next, a)
+        self.assertEqual(a.prev, b)
+
+        self.assertEqual(root.append_child(c), 2)
+        self.assertEqual(root.n_children(),    3)
+        self.assertEqual(root.children, [ b, a, c ])
+        self.assertEqual(a.next, c)
+        self.assertEqual(c.prev, a)
+
     def test_node_insert_child(self):
         root = node.PlaylistNode()
         a = node.PlaylistNode("a")