Fixed check for open file

- fixed opening of file with file descriptor
- fixes pytest-dev#282

fake_filesystem_test.py

@@ -4599,7 +4599,7 @@ def testReadWithRplus(self):
         fake_file.close()
 
     def testAccessingClosedFileRaises(self):
-        self.filesystem.is_windows_fs = False
+        # self.filesystem.is_windows_fs = False
         self.filesystem.CreateFile(self.file_path, contents=b'test')
         fake_file = self.open(self.file_path, 'r')
         fake_file.close()
@@ -4610,6 +4610,12 @@ def testAccessingClosedFileRaises(self):
         self.assertRaises(ValueError, lambda: fake_file.tell())
         self.assertRaises(ValueError, lambda: fake_file.seek(1))
 
+    def testAccessingOpenFileWithAnotherHandleRaises(self):
+        self.os.open(self.file_path, os.O_CREAT | os.O_WRONLY | os.O_TRUNC)
+        fake_file = self.open(self.file_path, 'r')
+        fake_file.close()
+        self.assertRaises(ValueError, lambda: fake_file.read(1))
+        self.assertRaises(ValueError, lambda: fake_file.write(1))
 
 class OpenWithFileDescriptorTest(FakeFileOpenTestBase):
     @unittest.skipIf(sys.version_info < (3, 0), 'only tested on 3.0 or greater')

pyfakefs/fake_filesystem.py

@@ -4302,10 +4302,7 @@ def write_error(*args, **kwargs):
         return getattr(self._io, name)
 
     def _check_open_file(self):
-        open_files = [wrapper.GetObject() for wrapper
-                      in self._filesystem.open_files if wrapper]
-        is_open = self._file_object in open_files
-        if not self._is_stream and not is_open:
+        if not self._is_stream and not self in self._filesystem.open_files:
             raise ValueError('I/O operation on closed file')
 
     def __iter__(self):
@@ -4467,6 +4464,8 @@ def Call(self, file_, mode='r', buffering=-1, encoding=None,
                                    raw_io=self.raw_io)
         if filedes is not None:
             fakefile.filedes = filedes
+            # replace the file wrapper
+            self.filesystem.open_files[filedes] = fakefile
         else:
             fakefile.filedes = self.filesystem.AddOpenFile(fakefile)
         return fakefile