#17616: Improve context manager tests, fix bugs in close method and mode docs.

'mode' docs fix: the file must always be opened in binary in Python3.

Bug in Wave_write.close: when the close method calls the check that the header
exists and it raises an error, the _file attribute never gets set to None, so
the next close tries to close the file again and we get an ignored traceback
in the __del__ method.  The fix is to set _file to None in a finally clause.
This represents a behavior change...in theory a program could be checking for
the error on close and then doing a recovery action on the still open file and
closing it again.  But this change will only go into 3.4, so I think that
behavior change is acceptable given that it would be pretty weird and unlikely
logic to begin with.

1 files changed, 7 insertions, 5 deletions

diff --git a/Lib/wave.py b/Lib/wave.py
index 695a4be..f43569e 100644
--- a/Lib/wave.py
+++ b/Lib/wave.py
@@ -448,11 +448,13 @@ class Wave_write:
 
     def close(self):
         if self._file:
-            self._ensure_header_written(0)
-            if self._datalength != self._datawritten:
-                self._patchheader()
-            self._file.flush()
-            self._file = None
+            try:
+                self._ensure_header_written(0)
+                if self._datalength != self._datawritten:
+                    self._patchheader()
+                self._file.flush()
+            finally:
+                self._file = None
         if self._i_opened_the_file:
             self._i_opened_the_file.close()
             self._i_opened_the_file = None