Revert "bpo-36543: Remove the xml.etree.cElementTree module. (GH-19108)"

This reverts commit b33e525.

Author: serhiy-storchaka

Lib/test/test_xml_etree_c.py

@@ -8,6 +8,9 @@
 
 cET = import_fresh_module('xml.etree.ElementTree',
                           fresh=['_elementtree'])
+cET_alias = import_fresh_module('xml.etree.cElementTree',
+                                fresh=['_elementtree', 'xml.etree'],
+                                deprecated=True)
 
 
 @unittest.skipUnless(cET, 'requires _elementtree')
@@ -167,6 +170,14 @@ def test_xmlpullparser_leaks(self):
         support.gc_collect()
 
 
+@unittest.skipUnless(cET, 'requires _elementtree')
+class TestAliasWorking(unittest.TestCase):
+    # Test that the cET alias module is alive
+    def test_alias_working(self):
+        e = cET_alias.Element('foo')
+        self.assertEqual(e.tag, 'foo')
+
+
 @unittest.skipUnless(cET, 'requires _elementtree')
 @support.cpython_only
 class TestAcceleratorImported(unittest.TestCase):
@@ -175,6 +186,9 @@ def test_correct_import_cET(self):
         # SubElement is a function so it retains _elementtree as its module.
         self.assertEqual(cET.SubElement.__module__, '_elementtree')
 
+    def test_correct_import_cET_alias(self):
+        self.assertEqual(cET_alias.SubElement.__module__, '_elementtree')
+
     def test_parser_comes_from_C(self):
         # The type of methods defined in Python code is types.FunctionType,
         # while the type of methods defined inside _elementtree is
@@ -214,6 +228,7 @@ def test_main():
     # Run the tests specific to the C implementation
     support.run_unittest(
         MiscTests,
+        TestAliasWorking,
         TestAcceleratorImported,
         SizeofTest,
         )

Lib/xml/etree/cElementTree.py

@@ -0,0 +1,3 @@
+# Deprecated alias for xml.etree.ElementTree
+
+from xml.etree.ElementTree import *