bpo-25862: Fix assertion failures in io.TextIOWrapper.tell(). (GH-3918)
(cherry picked from commit 23db935bcf258657682e66464bf8512def8af830)
Co-authored-by: Zackery Spytz <zspytz@gmail.com>
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index c91a647..f0d4f4e 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -2149,6 +2149,7 @@
self.buffer.write(b)
if self._line_buffering and (haslf or "\r" in s):
self.flush()
+ self._set_decoded_chars('')
self._snapshot = None
if self._decoder:
self._decoder.reset()
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 286ae76..a03a7f7 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -3549,6 +3549,17 @@
expected = 'linesep' + os.linesep + 'LF\nLF\nCR\rCRLF\r\n'
self.assertEqual(txt.detach().getvalue().decode('ascii'), expected)
+ def test_issue25862(self):
+ # Assertion failures occurred in tell() after read() and write().
+ t = self.TextIOWrapper(self.BytesIO(b'test'), encoding='ascii')
+ t.read(1)
+ t.read()
+ t.tell()
+ t = self.TextIOWrapper(self.BytesIO(b'test'), encoding='ascii')
+ t.read(1)
+ t.write('x')
+ t.tell()
+
class MemviewBytesIO(io.BytesIO):
'''A BytesIO object whose read method returns memoryviews