diff options
Diffstat (limited to 'Lib/test/test_io.py')
| -rw-r--r-- | Lib/test/test_io.py | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py index 1f1cba2..a9094d9 100644 --- a/Lib/test/test_io.py +++ b/Lib/test/test_io.py @@ -1328,6 +1328,26 @@ class BufferedRandomTest(BufferedReaderTest, BufferedWriterTest): bufio.readinto(bytearray(1)) self.check_writes(_read) + def test_write_after_readahead(self): + # Issue #6629: writing after the buffer was filled by readahead should + # first rewind the raw stream. + for overwrite_size in [1, 5]: + raw = self.BytesIO(b"A" * 10) + bufio = self.tp(raw, 4) + # Trigger readahead + self.assertEqual(bufio.read(1), b"A") + self.assertEqual(bufio.tell(), 1) + # Overwriting should rewind the raw stream if it needs so + bufio.write(b"B" * overwrite_size) + self.assertEqual(bufio.tell(), overwrite_size + 1) + # If the write size was smaller than the buffer size, flush() and + # check that rewind happens. + bufio.flush() + self.assertEqual(bufio.tell(), overwrite_size + 1) + s = raw.getvalue() + self.assertEqual(s, + b"A" + b"B" * overwrite_size + b"A" * (9 - overwrite_size)) + def test_misbehaved_io(self): BufferedReaderTest.test_misbehaved_io(self) BufferedWriterTest.test_misbehaved_io(self) |