Fix junitxml count for teardown errors

[puneetdixit200]

Fixes #3850

Summary

• correct the JUnit XML tests count when a test passes during call but fails during teardown
• assert in run_and_parse that the testsuite tests attribute matches the emitted <testcase> nodes
• keep call-failure plus teardown-error as separate testcase nodes, while the pass-plus-teardown-error path stays one testcase node
• add a changelog entry

Tests

• .venv/bin/python -m pytest testing/test_junitxml.py -q
• .venv/bin/pre-commit run --color never --files src/_pytest/junitxml.py testing/test_junitxml.py changelog/3850.bugfix.rst
• git diff --check

AI assistance was used while iterating on the patch and tests. I reviewed the change and can explain it.

[nicoddemus]

Thanks, left some comments!

[nicoddemus]

I believe we should convert these tests to use run_and_parse instead of calling the hooks manually.

[nicoddemus]

We should assert that the tests="X" header item matches the number of <testcase> items in the XML.

[nicoddemus]

Given this should be an invariant, I applied this diff to run_and_parse in main:

diff --git a/testing/test_junitxml.py b/testing/test_junitxml.py
index 5a603c05b..f043a002f 100644
--- a/testing/test_junitxml.py
+++ b/testing/test_junitxml.py
@@ -49,7 +49,11 @@ class RunAndParse:
             with xml_path.open(encoding="utf-8") as f:
                 self.schema.validate(f)
         xmldoc = minidom.parse(str(xml_path))
-        return result, DomDocument(xmldoc)
+        doc = DomDocument(xmldoc)
+        testcase_nodes = doc.find_by_tag("testcase")
+        test_suite_node = doc.get_first_by_tag("testsuite")
+        test_suite_node.assert_attr(name="pytest", tests=len(testcase_nodes))
+        return result, doc

And that alone caused 9 out of 137 tests to fail already. We might not even need additional tests, an existing test might already be catching the original issue, it wasn't testing the tests header against the number of testcases in the file.

[nicoddemus]

Please add a comment explanation this case, possibly with a link to the issue.

[puneetdixit200]

Rebased onto current main to pick up the unittest skip fixture fix from #14505.

Verification run locally:

uv run --with-editable . --extra dev python -m pytest testing/test_junitxml.py testing/test_unittest.py::test_setup_inheritance_skipping testing/test_unittest.py::test_pdb_teardown_skipped_for_classes testing/test_debugging.py::TestPDB::test_pdb_unittest_skip -q --junitxml=/tmp/pytest-14501-after-rebase.xml
# 142 passed, 3 skipped