- Issue #6939: Fix file I/O objects in the `io` module to keep the original
file position when calling `truncate()`. It would previously change the
file position to the given argument, which goes against the tradition of
ftruncate() and other truncation APIs. Patch by Pascal Chambon.
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index 91c5251..cdc3123 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -329,6 +329,17 @@
f.close()
self.fail("no error for invalid mode: %s" % bad_mode)
+ def testTruncate(self):
+ f = _FileIO(TESTFN, 'w')
+ f.write(bytes(bytearray(range(10))))
+ self.assertEqual(f.tell(), 10)
+ f.truncate(5)
+ self.assertEqual(f.tell(), 10)
+ self.assertEqual(f.seek(0, os.SEEK_END), 5)
+ f.truncate(15)
+ self.assertEqual(f.tell(), 5)
+ self.assertEqual(f.seek(0, os.SEEK_END), 15)
+
def testTruncateOnWindows(self):
def bug801631():
# SF bug <http://www.python.org/sf/801631>