Re-add cElementTree module and deprecate it

``xml.etree.ElementTree`` was re-added before Python 3.9.0 release. The
alias will be removed in a future release.

Signed-off-by: Christian Heimes <christian@python.org>

1 files changed, 11 insertions, 9 deletions

diff --git a/tests.py b/tests.py
index 188200a..f8b9274 100644
--- a/tests.py
+++ b/tests.py
@@ -18,13 +18,15 @@ from defusedxml import (
     ExternalReferenceForbidden,
     NotSupportedError,
 )
-from defusedxml.common import PY3, _HAVE_CELEMENTTREE
+from defusedxml.common import PY3
 
 
-if _HAVE_CELEMENTTREE:
+if sys.version_info < (3, 7):
+    warnings.filterwarnings("once", category=DeprecationWarning)
+
+
+with warnings.catch_warnings(record=True) as cetree_warnings:
     from defusedxml import cElementTree
-else:
-    cElementTree = None
 
 
 try:
@@ -33,10 +35,6 @@ except ImportError:
     gzip = None
 
 
-if sys.version_info < (3, 7):
-    warnings.filterwarnings("once", category=DeprecationWarning)
-
-
 try:
     with warnings.catch_warnings(record=True) as lxml_warnings:
         from defusedxml import lxml
@@ -211,10 +209,14 @@ class TestDefusedElementTree(BaseTests):
         assert self.module.XMLParse is parser
 
 
-@unittest.skipUnless(_HAVE_CELEMENTTREE, "Python 3.9 has removed cElementTree")
 class TestDefusedcElementTree(TestDefusedElementTree):
     module = cElementTree
 
+    def test_celementtree_warnings(self):
+        self.assertTrue(cetree_warnings)
+        self.assertEqual(cetree_warnings[0].category, DeprecationWarning)
+        self.assertIn("tests.py", cetree_warnings[0].filename)
+
 
 class TestDefusedMinidom(BaseTests):
     module = minidom