Merged revisions 77895-77896 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r77895 | antoine.pitrou | 2010-01-31 23:47:27 +0100 (dim., 31 janv. 2010) | 12 lines

  Merged revisions 77890 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r77890 | antoine.pitrou | 2010-01-31 23:26:04 +0100 (dim., 31 janv. 2010) | 7 lines

    - 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.
  ........
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  r77896 | antoine.pitrou | 2010-02-01 00:12:29 +0100 (lun., 01 févr. 2010) | 3 lines

  r77895 broke doctest.
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diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index 7a9b780..f89c542 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -330,6 +330,17 @@
             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>
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 2f76fed..71362f0 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -229,6 +229,11 @@
 
     def write_ops(self, f):
         self.assertEqual(f.write(b"blah."), 5)
+        f.truncate(0)
+        self.assertEqual(f.tell(), 5)
+        f.seek(0)
+
+        self.assertEqual(f.write(b"blah."), 5)
         self.assertEqual(f.seek(0), 0)
         self.assertEqual(f.write(b"Hello."), 6)
         self.assertEqual(f.tell(), 6)
@@ -239,8 +244,9 @@
         self.assertEqual(f.write(b"h"), 1)
         self.assertEqual(f.seek(-1, 2), 13)
         self.assertEqual(f.tell(), 13)
+
         self.assertEqual(f.truncate(12), 12)
-        self.assertEqual(f.tell(), 12)
+        self.assertEqual(f.tell(), 13)
         self.assertRaises(TypeError, f.seek, 0.0)
 
     def read_ops(self, f, buffered=False):
@@ -285,7 +291,7 @@
         self.assertEqual(f.tell(), self.LARGE + 2)
         self.assertEqual(f.seek(0, 2), self.LARGE + 2)
         self.assertEqual(f.truncate(self.LARGE + 1), self.LARGE + 1)
-        self.assertEqual(f.tell(), self.LARGE + 1)
+        self.assertEqual(f.tell(), self.LARGE + 2)
         self.assertEqual(f.seek(0, 2), self.LARGE + 1)
         self.assertEqual(f.seek(-1, 2), self.LARGE)
         self.assertEqual(f.read(2), b"x")
@@ -980,7 +986,7 @@
             bufio = self.tp(raw, 8)
             bufio.write(b"abcdef")
             self.assertEqual(bufio.truncate(3), 3)
-            self.assertEqual(bufio.tell(), 3)
+            self.assertEqual(bufio.tell(), 6)
         with self.open(support.TESTFN, "rb", buffering=0) as f:
             self.assertEqual(f.read(), b"abc")
 
@@ -1366,6 +1372,14 @@
             self.assertEqual(s,
                 b"A" + b"B" * overwrite_size + b"A" * (9 - overwrite_size))
 
+    def test_truncate_after_read_or_write(self):
+        raw = self.BytesIO(b"A" * 10)
+        bufio = self.tp(raw, 100)
+        self.assertEqual(bufio.read(2), b"AA") # the read buffer gets filled
+        self.assertEqual(bufio.truncate(), 2)
+        self.assertEqual(bufio.write(b"BB"), 2) # the write buffer increases
+        self.assertEqual(bufio.truncate(), 4)
+
     def test_misbehaved_io(self):
         BufferedReaderTest.test_misbehaved_io(self)
         BufferedWriterTest.test_misbehaved_io(self)
diff --git a/Lib/test/test_largefile.py b/Lib/test/test_largefile.py
index 7fd3e0e..1c6297a 100644
--- a/Lib/test/test_largefile.py
+++ b/Lib/test/test_largefile.py
@@ -122,14 +122,14 @@
             newsize -= 1
             f.seek(42)
             f.truncate(newsize)
-            self.assertEqual(f.tell(), newsize)  # else wasn't truncated
+            self.assertEqual(f.tell(), 42)
             f.seek(0, 2)
             self.assertEqual(f.tell(), newsize)
             # XXX truncate(larger than true size) is ill-defined
             # across platform; cut it waaaaay back
             f.seek(0)
             f.truncate(1)
-            self.assertEqual(f.tell(), 1)       # else pointer moved
+            self.assertEqual(f.tell(), 0)       # else pointer moved
             f.seek(0)
             self.assertEqual(len(f.read()), 1)  # else wasn't truncated
 
diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index 07c80436..89c8196 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -72,7 +72,7 @@
         self.assertEqual(f.seek(0), 0)
         self.assertEqual(f.write(t("h")), 1)
         self.assertEqual(f.truncate(12), 12)
-        self.assertEqual(f.tell(), 12)
+        self.assertEqual(f.tell(), 1)
 
     def test_write(self):
         buf = self.buftype("hello world\n")
@@ -120,7 +120,8 @@
         self.assertEqual(memio.getvalue(), buf[:6])
         self.assertEqual(memio.truncate(4), 4)
         self.assertEqual(memio.getvalue(), buf[:4])
-        self.assertEqual(memio.tell(), 4)
+        self.assertEqual(memio.tell(), 6)
+        memio.seek(0, 2)
         memio.write(buf)
         self.assertEqual(memio.getvalue(), buf[:4] + buf)
         pos = memio.tell()