Implement of interface NodeList

w3/python/core/fundamental_interface/NodeList.py

@@ -0,0 +1,36 @@
+from typing import Optional
+
+from w3.python.core.fundamental_interface.Node import Node
+
+
+_AnyNode = Node
+
+class NodeList(list):
+    """Interface NodeList
+
+    The `NodeList` interface provides the abstraction of an ordered collection of nodes, without defining or constraining how this collection is implemented.
+    The items in the `NodeList` are accessible via an integral index, starting from 0.
+    """
+
+    @property
+    def length(self) -> int:
+        """The number of nodes in the list. The range of valid child node indices is 0 to `length`-1 inclusive.
+        """
+        return len(self)
+
+
+    def item(self, index: int) -> Optional[_AnyNode]:
+        """Returns the indexth item in the collection. If index is greater than or equal to the number of nodes in the list, this returns null.
+
+        Args:
+            index: Index into the collection.
+
+        Returns:
+            The node at the `index`th position in the `NodeList`, or `None` if that is not a valid index.
+
+        This method raises no exceptions.
+        """
+        if isinstance(index, int):
+            if 0 <= index < self.length:
+                return self[index]
+        return None

w3/python/core/fundamental_interface/NodeList_test.py

@@ -0,0 +1,69 @@
+from typing import Iterator
+import unittest
+
+from w3.python.core.fundamental_interface.DOMException import DOMException
+from w3.python.core.fundamental_interface.Node import Node
+from w3.python.core.fundamental_interface.Node import NodeType
+from w3.python.core.fundamental_interface.NodeList import NodeList
+
+
+def _make_nodes(n: int) -> Iterator[Node]:
+    """Accessor to create `n` random nodes immediatly.
+
+    Args:
+        n: number of nodes to generate.
+
+    Yields:
+        A randomly generated node.
+    """
+    for _ in range(n):
+        yield Node(NodeType.TEXT_NODE, '#text')
+
+
+class Test_NodeList(unittest.TestCase):
+    def testInit(self):
+        NodeList()
+        # Initiate with a node
+        node = next(_make_nodes(1))
+        NodeList([node])
+        # Initiate with multiple nodes.
+        NodeList(_make_nodes(4))
+
+    def testIter(self):
+        nodes = [*_make_nodes(4)]
+        node_list = NodeList(nodes)
+        # Create an iterator for checking
+        node_iter = iter(nodes)
+        for list_elem in node_list:
+            self.assertEqual(list_elem, next(node_iter))
+
+    def testItem_inSize(self):
+        nodes = [*_make_nodes(5)]
+        node_list = NodeList(nodes)
+        for i in range(5):
+            self.assertEqual(node_list.item(i), nodes[i])
+
+    def testItem_greaterOrEqualThanSize(self):
+        node_list = NodeList(_make_nodes(5))
+        for i in range(5, 8):
+            self.assertIsNone(node_list.item(i))
+
+    def testItem_notValid(self):
+        node_list = NodeList(_make_nodes(5))
+        for idx in [-1, -9999, 'hi', '1', None, Node, NodeList, b'0']:
+            self.assertIsNone(node_list.item(idx))
+
+    def testLength(self):
+        # Empty NodeList
+        node_list = NodeList()
+        self.assertEqual(node_list.length, 0)
+        # NodeList with a node.
+        node_list = NodeList(_make_nodes(1))
+        self.assertEqual(node_list.length, 1)
+        # NodeList with some items.
+        node_list = NodeList(_make_nodes(5))
+        self.assertEqual(node_list.length, 5)
+
+
+if __name__ == '__main__':
+    unittest.main()