#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.

2 files changed, 47 insertions, 18 deletions

diff --git a/Lib/test/test_wave.py b/Lib/test/test_wave.py
index e9ee15c..c505fb8 100644
--- a/Lib/test/test_wave.py
+++ b/Lib/test/test_wave.py
@@ -69,22 +69,49 @@ class TestWave(unittest.TestCase):
         self.assertEqual(params.comptype, self.f.getcomptype())
         self.assertEqual(params.compname, self.f.getcompname())
 
-    def test_context_manager(self):
-        self.f = wave.open(TESTFN, 'wb')
-        self.f.setnchannels(nchannels)
-        self.f.setsampwidth(sampwidth)
-        self.f.setframerate(framerate)
-        self.f.close()
+    def test_wave_write_context_manager_calls_close(self):
+        # Close checks for a minimum header and will raise an error
+        # if it is not set, so this proves that close is called.
+        with self.assertRaises(wave.Error):
+            with wave.open(TESTFN, 'wb') as f:
+                pass
+        print('in test:', f._file)
+        with self.assertRaises(wave.Error):
+            with open(TESTFN, 'wb') as testfile:
+                with wave.open(testfile):
+                    pass
 
+    def test_context_manager_with_open_file(self):
+        with open(TESTFN, 'wb') as testfile:
+            with wave.open(testfile) as f:
+                f.setnchannels(nchannels)
+                f.setsampwidth(sampwidth)
+                f.setframerate(framerate)
+            self.assertFalse(testfile.closed)
+        with open(TESTFN, 'rb') as testfile:
+            with wave.open(testfile) as f:
+                self.assertFalse(f.getfp().closed)
+                params = f.getparams()
+                self.assertEqual(params.nchannels, nchannels)
+                self.assertEqual(params.sampwidth, sampwidth)
+                self.assertEqual(params.framerate, framerate)
+            self.assertIsNone(f.getfp())
+            self.assertFalse(testfile.closed)
+
+    def test_context_manager_with_filename(self):
+        # If the file doesn't get closed, this test won't fail, but it will
+        # produce a resource leak warning.
+        with wave.open(TESTFN, 'wb') as f:
+            f.setnchannels(nchannels)
+            f.setsampwidth(sampwidth)
+            f.setframerate(framerate)
         with wave.open(TESTFN) as f:
             self.assertFalse(f.getfp().closed)
-        self.assertIs(f.getfp(), None)
-
-        with open(TESTFN, 'wb') as testfile:
-            with self.assertRaises(wave.Error):
-                with wave.open(testfile, 'wb'):
-                    pass
-            self.assertEqual(testfile.closed, False)
+            params = f.getparams()
+            self.assertEqual(params.nchannels, nchannels)
+            self.assertEqual(params.sampwidth, sampwidth)
+            self.assertEqual(params.framerate, framerate)
+        self.assertIsNone(f.getfp())
 
 
 if __name__ == '__main__':
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