Issue #13782: streamline argument type-checking in ET.Element

eliben · eliben · commit 396e8fcf3648 · 2012-03-23T14:24:20.000+02:00
append, extend and insert now consistently type-check their argument in both
the C and Python implementations, and raise TypeError for non-Element
argument.

Added tests
diff --git a/Doc/library/xml.etree.elementtree.rst b/Doc/library/xml.etree.elementtree.rst
@@ -281,14 +281,15 @@ Element Objects
 
    .. method:: append(subelement)
 
-      Adds the element *subelement* to the end of this elements internal list
-      of subelements.
+      Adds the element *subelement* to the end of this element's internal list
+      of subelements.  Raises :exc:`TypeError` if *subelement* is not an
+      :class:`Element`.
 
 
    .. method:: extend(subelements)
 
       Appends *subelements* from a sequence object with zero or more elements.
-      Raises :exc:`AssertionError` if a subelement is not a valid object.
+      Raises :exc:`TypeError` if a subelement is not an :class:`Element`.
 
       .. versionadded:: 3.2
 
@@ -325,9 +326,10 @@ Element Objects
          Use method :meth:`Element.iter` instead.
 
 
-   .. method:: insert(index, element)
+   .. method:: insert(index, subelement)
 
-      Inserts a subelement at the given position in this element.
+      Inserts *subelement* at the given position in this element.  Raises
+      :exc:`TypeError` if *subelement* is not an :class:`Element`.
 
 
    .. method:: iter(tag=None)
diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
@@ -1839,8 +1839,15 @@ def check_issue10777():
 # --------------------------------------------------------------------
 
 
-class ElementTreeTest(unittest.TestCase):
+class BasicElementTest(unittest.TestCase):
+    def test_augmentation_type_errors(self):
+        e = ET.Element('joe')
+        self.assertRaises(TypeError, e.append, 'b')
+        self.assertRaises(TypeError, e.extend, [ET.Element('bar'), 'foo'])
+        self.assertRaises(TypeError, e.insert, 0, 'foo')
+
 
+class ElementTreeTest(unittest.TestCase):
     def test_istype(self):
         self.assertIsInstance(ET.ParseError, type)
         self.assertIsInstance(ET.QName, type)
@@ -1879,7 +1886,6 @@ def newmethod(self):
 
 
 class TreeBuilderTest(unittest.TestCase):
-
     sample1 = ('<!DOCTYPE html PUBLIC'
         ' "-//W3C//DTD XHTML 1.0 Transitional//EN"'
         ' "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">'
@@ -1931,7 +1937,6 @@ def close(self):
 
 
 class NoAcceleratorTest(unittest.TestCase):
-
     # Test that the C accelerator was not imported for pyET
     def test_correct_import_pyET(self):
         self.assertEqual(pyET.Element.__module__, 'xml.etree.ElementTree')
@@ -2096,6 +2101,7 @@ def test_main(module=pyET):
 
     test_classes = [
         ElementSlicingTest,
+        BasicElementTest,
         StringIOTest,
         ParseErrorTest,
         ElementTreeTest,
diff --git a/Lib/xml/etree/ElementTree.py b/Lib/xml/etree/ElementTree.py
@@ -298,7 +298,7 @@ def __delitem__(self, index):
     # @param element The element to add.
 
     def append(self, element):
-        # assert iselement(element)
+        self._assert_is_element(element)
         self._children.append(element)
 
     ##
@@ -308,8 +308,8 @@ def append(self, element):
     # @since 1.3
 
     def extend(self, elements):
-        # for element in elements:
-        #     assert iselement(element)
+        for element in elements:
+            self._assert_is_element(element)
         self._children.extend(elements)
 
     ##
@@ -318,9 +318,13 @@ def extend(self, elements):
     # @param index Where to insert the new subelement.
 
     def insert(self, index, element):
-        # assert iselement(element)
+        self._assert_is_element(element)
         self._children.insert(index, element)
 
+    def _assert_is_element(self, e):
+        if not isinstance(e, Element):
+            raise TypeError('expected an Element, not %s' % type(e).__name__)
+
     ##
     # Removes a matching subelement.  Unlike the <b>find</b> methods,
     # this method compares elements based on identity, not on tag
diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
@@ -803,6 +803,15 @@ element_extend(ElementObject* self, PyObject* args)
     seqlen = PySequence_Size(seq);
     for (i = 0; i < seqlen; i++) {
         PyObject* element = PySequence_Fast_GET_ITEM(seq, i);
+        if (!PyObject_IsInstance(element, (PyObject *)&Element_Type)) {
+            Py_DECREF(seq);
+            PyErr_Format(
+                PyExc_TypeError,
+                "expected an Element, not \"%.200s\"",
+                Py_TYPE(element)->tp_name);
+            return NULL;
+        }
+
         if (element_add_subelement(self, element) < 0) {
             Py_DECREF(seq);
             return NULL;
