Merge pull request pandas-dev#10490 from kawochen/BUG-FIX-10369

TST/ERR: GH10369 read_msgpack checks argument type

Author: jreback

doc/source/whatsnew/v0.17.0.txt

@@ -131,3 +131,4 @@ Bug Fixes
 - Bug in ``DatetimeIndex`` and ``PeriodIndex.value_counts`` resets name from its result, but retains in result's ``Index``. (:issue:`10150`)
 
 - Bug in `pandas.concat` with ``axis=0`` when column is of dtype ``category`` (:issue:`10177`)
+- Bug in ``read_msgpack`` where input type is not always checked (:issue:`10369`)

pandas/io/packers.py

@@ -141,24 +141,28 @@ def read(fh):
 
         try:
             exists = os.path.exists(path_or_buf)
-        except (TypeError,ValueError):
+        except (TypeError, ValueError):
             exists = False
 
         if exists:
             with open(path_or_buf, 'rb') as fh:
                 return read(fh)
 
-    # treat as a string-like
-    if not hasattr(path_or_buf, 'read'):
-
+    # treat as a binary-like
+    if isinstance(path_or_buf, compat.binary_type):
+        fh = None
         try:
             fh = compat.BytesIO(path_or_buf)
             return read(fh)
         finally:
-            fh.close()
+            if fh is not None:
+                fh.close()
 
     # a buffer like
-    return read(path_or_buf)
+    if hasattr(path_or_buf, 'read') and compat.callable(path_or_buf.read):
+        return read(path_or_buf)
+
+    raise ValueError('path_or_buf needs to be a string file path or file-like')
 
 dtype_dict = {21: np.dtype('M8[ns]'),
               u('datetime64[ns]'): np.dtype('M8[ns]'),

pandas/io/tests/test_packers.py

@@ -93,6 +93,17 @@ def test_iterator_with_string_io(self):
         for i, result in enumerate(read_msgpack(s,iterator=True)):
             tm.assert_frame_equal(result,dfs[i])
 
+    def test_invalid_arg(self):
+        #GH10369
+        class A(object):
+            def __init__(self):
+                self.read = 0
+
+        tm.assertRaises(ValueError, read_msgpack, path_or_buf=None)
+        tm.assertRaises(ValueError, read_msgpack, path_or_buf={})
+        tm.assertRaises(ValueError, read_msgpack, path_or_buf=A())
+
+
 class TestNumpy(TestPackers):
 
     def test_numpy_scalar_float(self):