core[patch]: XMLOutputParser fix to handle changes to xml standard library (#19612)

Newest python micro releases broke streaming in the XMLOutputParser. This fixes the parsing code to work with trailing junk after the XML content.

libs/core/tests/unit_tests/output_parsers/test_xml_parser.py

@@ -1,10 +1,12 @@
 """Test XMLOutputParser"""
+from typing import AsyncIterator, Iterable
+
 import pytest
 
 from langchain_core.exceptions import OutputParserException
 from langchain_core.output_parsers.xml import XMLOutputParser
 
-DEF_RESULT_ENCODING = """<?xml version="1.0" encoding="UTF-8"?>
+DATA = """
  <foo>
     <bar>
         <baz></baz>
@@ -13,6 +15,25 @@ DEF_RESULT_ENCODING = """<?xml version="1.0" encoding="UTF-8"?>
     <baz>tag</baz>
 </foo>"""
 
+WITH_XML_HEADER = f"""<?xml version="1.0" encoding="UTF-8"?>
+{DATA}"""
+
+
+IN_XML_TAGS_WITH_XML_HEADER = f"""
+```xml
+{WITH_XML_HEADER}
+```
+"""
+
+IN_XML_TAGS_WITH_HEADER_AND_TRAILING_JUNK = f"""
+Some random text
+```xml
+{WITH_XML_HEADER}
+```
+More random text
+"""
+
+
 DEF_RESULT_EXPECTED = {
     "foo": [
         {"bar": [{"baz": None}, {"baz": "slim.shady"}]},
@@ -24,23 +45,13 @@ DEF_RESULT_EXPECTED = {
 @pytest.mark.parametrize(
     "result",
     [
-        DEF_RESULT_ENCODING,
-        DEF_RESULT_ENCODING[DEF_RESULT_ENCODING.find("\n") :],
-        f"""
-```xml
-{DEF_RESULT_ENCODING}
-```
-""",
-        f"""
-Some random text
-```xml
-{DEF_RESULT_ENCODING}
-```
-More random text
-""",
+        DATA,  # has no xml header
+        WITH_XML_HEADER,
+        IN_XML_TAGS_WITH_XML_HEADER,
+        IN_XML_TAGS_WITH_HEADER_AND_TRAILING_JUNK,
     ],
 )
-def test_xml_output_parser(result: str) -> None:
+async def test_xml_output_parser(result: str) -> None:
     """Test XMLOutputParser."""
 
     xml_parser = XMLOutputParser()
@@ -48,12 +59,23 @@ def test_xml_output_parser(result: str) -> None:
     xml_result = xml_parser.parse(result)
     assert DEF_RESULT_EXPECTED == xml_result
 
-    # TODO(Eugene): Fix this test for newer python version
-    # assert list(xml_parser.transform(iter(result))) == [
-    #     {"foo": [{"bar": [{"baz": None}]}]},
-    #     {"foo": [{"bar": [{"baz": "slim.shady"}]}]},
-    #     {"foo": [{"baz": "tag"}]},
-    # ]
+    assert list(xml_parser.transform(iter(result))) == [
+        {"foo": [{"bar": [{"baz": None}]}]},
+        {"foo": [{"bar": [{"baz": "slim.shady"}]}]},
+        {"foo": [{"baz": "tag"}]},
+    ]
+
+    async def _as_iter(iterable: Iterable[str]) -> AsyncIterator[str]:
+        for item in iterable:
+            yield item
+
+    chunks = [chunk async for chunk in xml_parser.atransform(_as_iter(result))]
+
+    assert list(chunks) == [
+        {"foo": [{"bar": [{"baz": None}]}]},
+        {"foo": [{"bar": [{"baz": "slim.shady"}]}]},
+        {"foo": [{"baz": "tag"}]},
+    ]
 
 
 @pytest.mark.parametrize("result", ["foo></foo>", "<foo></foo", "foo></foo", "foofoo"])