Require FS.openbin to return a file-handle in binary mode (#435)

* Add test to ensure mode of files opened with `openbin` contain `b` flag
* Fix `FTPFS.openbin` not implicitly converting mode to binary mode
* Add missing `mode` attribute to `_MemoryFile` objects
* Add missing type annotation to `_MemoryFile.mode` property

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [2.4.12] - (Unreleased)
 
+### Added
+
+- Missing `mode` attribute to `_MemoryFile` objects returned by `MemoryFS.openbin`.
+
 ### Changed
 
 - Start testing on PyPy. Due to [#342](https://github.com/PyFilesystem/pyfilesystem2/issues/342)
@@ -23,6 +27,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed documentation of `Mode.to_platform_bin`. Closes [#382](https://github.com/PyFilesystem/pyfilesystem2/issues/382).
 - Fixed the code example in the "Testing Filesystems" section of the
   "Implementing Filesystems" guide. Closes [#407](https://github.com/PyFilesystem/pyfilesystem2/issues/407).
+- Fixed `FTPFS.openbin` not implicitly opening files in binary mode like expected
+  from `openbin`. Closes [#406](https://github.com/PyFilesystem/pyfilesystem2/issues/406).
 
 ## [2.4.11] - 2019-09-07
 

fs/ftpfs.py

@@ -682,7 +682,7 @@ def openbin(self, path, mode="r", buffering=-1, **options):
                     raise errors.FileExpected(path)
                 if _mode.exclusive:
                     raise errors.FileExists(path)
-            ftp_file = FTPFile(self, _path, mode)
+            ftp_file = FTPFile(self, _path, _mode.to_platform_bin())
         return ftp_file  # type: ignore
 
     def remove(self, path):

fs/memoryfs.py

@@ -75,6 +75,11 @@ def __str__(self):
         _template = "<memoryfile '{path}' '{mode}'>"
         return _template.format(path=self._path, mode=self._mode)
 
+    @property
+    def mode(self):
+        # type: () -> Text
+        return self._mode.to_platform_bin()
+
     @contextlib.contextmanager
     def _seek_lock(self):
         # type: () -> Iterator[None]

fs/test.py

@@ -774,6 +774,7 @@ def test_openbin_rw(self):
 
         with self.fs.openbin("foo/hello", "w") as f:
             repr(f)
+            self.assertIn("b", f.mode)
             self.assertIsInstance(f, io.IOBase)
             self.assertTrue(f.writable())
             self.assertFalse(f.readable())
@@ -787,6 +788,7 @@ def test_openbin_rw(self):
 
         # Read it back
         with self.fs.openbin("foo/hello", "r") as f:
+            self.assertIn("b", f.mode)
             self.assertIsInstance(f, io.IOBase)
             self.assertTrue(f.readable())
             self.assertFalse(f.writable())
@@ -927,6 +929,7 @@ def test_openbin(self):
         with self.fs.openbin("file.bin", "wb") as write_file:
             repr(write_file)
             text_type(write_file)
+            self.assertIn("b", write_file.mode)
             self.assertIsInstance(write_file, io.IOBase)
             self.assertTrue(write_file.writable())
             self.assertFalse(write_file.readable())
@@ -938,6 +941,7 @@ def test_openbin(self):
         with self.fs.openbin("file.bin", "rb") as read_file:
             repr(write_file)
             text_type(write_file)
+            self.assertIn("b", read_file.mode)
             self.assertIsInstance(read_file, io.IOBase)
             self.assertTrue(read_file.readable())
             self.assertFalse(read_file.writable())