Jul 26, 2022 · Jun 14, 2022 · Jun 14, 2022
diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
        tree = ET.ElementTree(ET.XML('''<site>\xf8</site>'''))
        tree.write(TESTFN, encoding='unicode')
        with open(TESTFN, 'rb') as f:
            data = f.read()
            expected = "<site>\xf8</site>".encode(encoding, 'xmlcharrefreplace')
            if encoding.lower() in ('utf-8', 'ascii'):
                self.assertEqual(data, expected)
            else:
                self.assertIn(b"<?xml version='1.0' encoding=", data)
                self.assertIn(expected, data)
            self.assertEqual(f.read(), b"<site>\xc3\xb8</site>")

    def test_write_to_text_file(self):
        self.addCleanup(os_helper.unlink, TESTFN)
            tree.write(f, encoding='unicode')
            self.assertFalse(f.closed)
        with open(TESTFN, 'rb') as f:
            self.assertEqual(f.read(),  convlinesep(
                             b'''<?xml version='1.0' encoding='ascii'?>\n'''
                             b'''<site>&#248;</site>'''))
            self.assertEqual(f.read(),  b'''<site>&#248;</site>''')

        with open(TESTFN, 'w', encoding='ISO-8859-1') as f:
            tree.write(f, encoding='unicode')
            self.assertFalse(f.closed)
        with open(TESTFN, 'rb') as f:
            self.assertEqual(f.read(),  convlinesep(
                             b'''<?xml version='1.0' encoding='ISO-8859-1'?>\n'''
                             b'''<site>\xf8</site>'''))
            self.assertEqual(f.read(), b'''<site>\xf8</site>''')

    def test_write_to_binary_file(self):
        self.addCleanup(os_helper.unlink, TESTFN)
diff --git a/Lib/xml/etree/ElementTree.py b/Lib/xml/etree/ElementTree.py
        with _get_writer(file_or_filename, encoding) as (write, declared_encoding):
            if method == "xml" and (xml_declaration or
                    (xml_declaration is None and
                     encoding.lower() != "unicode" and
                     declared_encoding.lower() not in ("utf-8", "us-ascii"))):
                write("<?xml version='1.0' encoding='%s'?>\n" % (
                    declared_encoding,))
    except AttributeError:
        # file_or_filename is a file name
        if encoding.lower() == "unicode":
            file = open(file_or_filename, "w",
                        errors="xmlcharrefreplace")
        else:
            file = open(file_or_filename, "w", encoding=encoding,
                        errors="xmlcharrefreplace")
        with file:
            yield file.write, file.encoding
            encoding="utf-8"
        with open(file_or_filename, "w", encoding=encoding,
                  errors="xmlcharrefreplace") as file:
            yield file.write, encoding
    else:
        # file_or_filename is a file-like object
        # encoding determines if it is a text or binary writer
diff --git a/Misc/NEWS.d/next/Library/2022-06-02-08-40-58.gh-issue-91810.Gtk44w.rst b/Misc/NEWS.d/next/Library/2022-06-02-08-40-58.gh-issue-91810.Gtk44w.rst
 Suppress writing an XML declaration in open files in ``ElementTree.write()``
 with ``encoding='unicode'`` and ``xml_declaration=None``.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -3739,13 +3739,7 @@ def test_write_to_filename_as_unicode(self):
		tree = ET.ElementTree(ET.XML('''<site>\xf8</site>'''))
		tree.write(TESTFN, encoding='unicode')
		with open(TESTFN, 'rb') as f:
		data = f.read()
		expected = "<site>\xf8</site>".encode(encoding, 'xmlcharrefreplace')
		if encoding.lower() in ('utf-8', 'ascii'):
		self.assertEqual(data, expected)
		else:
		self.assertIn(b"<?xml version='1.0' encoding=", data)
		self.assertIn(expected, data)
		self.assertEqual(f.read(), b"<site>\xc3\xb8</site>")

		def test_write_to_text_file(self):
		self.addCleanup(os_helper.unlink, TESTFN)
Expand All		@@ -3760,17 +3754,13 @@ def test_write_to_text_file(self):
		tree.write(f, encoding='unicode')
		self.assertFalse(f.closed)
		with open(TESTFN, 'rb') as f:
		self.assertEqual(f.read(), convlinesep(
		b'''<?xml version='1.0' encoding='ascii'?>\n'''
		b'''<site>ø</site>'''))
		self.assertEqual(f.read(), b'''<site>ø</site>''')

		with open(TESTFN, 'w', encoding='ISO-8859-1') as f:
		tree.write(f, encoding='unicode')
		self.assertFalse(f.closed)
		with open(TESTFN, 'rb') as f:
		self.assertEqual(f.read(), convlinesep(
		b'''<?xml version='1.0' encoding='ISO-8859-1'?>\n'''
		b'''<site>\xf8</site>'''))
		self.assertEqual(f.read(), b'''<site>\xf8</site>''')

		def test_write_to_binary_file(self):
		self.addCleanup(os_helper.unlink, TESTFN)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -731,6 +731,7 @@ def write(self, file_or_filename,
		with _get_writer(file_or_filename, encoding) as (write, declared_encoding):
		if method == "xml" and (xml_declaration or
		(xml_declaration is None and
		encoding.lower() != "unicode" and
		declared_encoding.lower() not in ("utf-8", "us-ascii"))):
		write("<?xml version='1.0' encoding='%s'?>\n" % (
		declared_encoding,))
Expand All		@@ -757,13 +758,10 @@ def _get_writer(file_or_filename, encoding):
		except AttributeError:
		# file_or_filename is a file name
		if encoding.lower() == "unicode":
		file = open(file_or_filename, "w",
		errors="xmlcharrefreplace")
		else:
		file = open(file_or_filename, "w", encoding=encoding,
		errors="xmlcharrefreplace")
		with file:
		yield file.write, file.encoding
		encoding="utf-8"
		with open(file_or_filename, "w", encoding=encoding,
		errors="xmlcharrefreplace") as file:
		yield file.write, encoding
		else:
		# file_or_filename is a file-like object
		# encoding determines if it is a text or binary writer
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Suppress writing an XML declaration in open files in ``ElementTree.write()``
		with ``encoding='unicode'`` and ``xml_declaration=None``.