Issue #12591: Allow io.TextIOWrapper to work with raw IO objects (without
a read1() method), and add an undocumented *write_through* parameter to
mandate unbuffered writes.
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 39fda2b..0ca621c 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -2307,6 +2307,27 @@
with self.assertRaises(AttributeError):
txt.buffer = buf
+ def test_rawio(self):
+ # Issue #12591: TextIOWrapper must work with raw I/O objects, so
+ # that subprocess.Popen() can have the required unbuffered
+ # semantics with universal_newlines=True.
+ raw = self.MockRawIO([b'abc', b'def', b'ghi\njkl\nopq\n'])
+ txt = self.TextIOWrapper(raw, encoding='ascii', newline='\n')
+ # Reads
+ self.assertEqual(txt.read(4), 'abcd')
+ self.assertEqual(txt.readline(), 'efghi\n')
+ self.assertEqual(list(txt), ['jkl\n', 'opq\n'])
+
+ def test_rawio_write_through(self):
+ # Issue #12591: with write_through=True, writes don't need a flush
+ raw = self.MockRawIO([b'abc', b'def', b'ghi\njkl\nopq\n'])
+ txt = self.TextIOWrapper(raw, encoding='ascii', newline='\n',
+ write_through=True)
+ txt.write('1')
+ txt.write('23\n4')
+ txt.write('5')
+ self.assertEqual(b''.join(raw._write_stack), b'123\n45')
+
class CTextIOWrapperTest(TextIOWrapperTest):
def test_initialization(self):