pythongh-91447: Fix findtext to only give an empty string on None (pythonGH-91486)

The API documentation for [findtext](https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.ElementTree.Element.findtext) states that this function gives back an empty string on "no text content." With the previous implementation, this would give back a empty string even on text content values such as 0 or False. This patch attempts to resolve that by only giving back an empty string if the text attribute is set to `None`. Resolves python#91447.

Automerge-Triggered-By: GH:gvanrossum

Author: eugenetriguba

Lib/test/test_xml_etree.py

@@ -2705,6 +2705,20 @@ def test_findtext_with_error(self):
         except ZeroDivisionError:
             pass
 
+    def test_findtext_with_falsey_text_attribute(self):
+        root_elem = ET.Element('foo')
+        sub_elem = ET.SubElement(root_elem, 'bar')
+        falsey = ["", 0, False, [], (), {}]
+        for val in falsey:
+            sub_elem.text = val
+            self.assertEqual(root_elem.findtext('./bar'), val)
+
+    def test_findtext_with_none_text_attribute(self):
+        root_elem = ET.Element('foo')
+        sub_elem = ET.SubElement(root_elem, 'bar')
+        sub_elem.text = None
+        self.assertEqual(root_elem.findtext('./bar'), '')
+
     def test_findall_with_mutating(self):
         e = ET.Element('foo')
         e.extend([ET.Element('bar')])

Lib/xml/etree/ElementPath.py

@@ -416,6 +416,8 @@ def findall(elem, path, namespaces=None):
 def findtext(elem, path, default=None, namespaces=None):
     try:
         elem = next(iterfind(elem, path, namespaces))
-        return elem.text or ""
+        if elem.text is None:
+            return ""
+        return elem.text
     except StopIteration:
         return default

Misc/NEWS.d/next/Library/2022-04-12-18-05-40.gh-issue-91447.N_Fs4H.rst

@@ -0,0 +1,2 @@
+Fix findtext in the xml module to only give an empty string when the text
+attribute is set to None.