When dtype is_dict_like is true, use get() instead of `values()…

…` in `pd.Series.astype`

pandas/core/generic.py

@@ -3509,10 +3509,10 @@ def astype(self, dtype, copy=True, errors='raise', **kwargs):
         """
         if is_dict_like(dtype):
             if self.ndim == 1:  # i.e. Series
-                if len(dtype) > 1 or list(dtype.keys())[0] != self.name:
+                if len(dtype) > 1 or self.name not in dtype.keys():
                     raise KeyError('Only the Series name can be used for '
                                    'the key in Series dtype mappings.')
-                new_type = list(dtype.values())[0]
+                new_type = dtype.get(self.name)
                 return self.astype(new_type, copy, errors, **kwargs)
             elif self.ndim > 2:
                 raise NotImplementedError(

pandas/tests/frame/test_dtypes.py

@@ -494,6 +494,13 @@ def test_astype_dict_like(self, dtype_class):
         assert_frame_equal(df, equiv)
         assert_frame_equal(df, original)
 
+        # if dtypes provided is empty, the resulting DataFrame
+        # should be the same as the original DataFrame
+        dt7 = dtype_class({})
+        equiv = df.astype(dt7)
+        assert_frame_equal(df, equiv)
+        assert_frame_equal(df, original)
+
     def test_astype_duplicate_col(self):
         a1 = Series([1, 2, 3, 4, 5], name='a')
         b = Series([0.1, 0.2, 0.4, 0.6, 0.8], name='b')

pandas/tests/series/test_dtypes.py

@@ -176,6 +176,11 @@ def test_astype_dict_like(self, dtype_class):
         with pytest.raises(KeyError):
             s.astype(dt4)
 
+        # if dtypes provided is empty, it should error
+        dt5 = dtype_class({})
+        with pytest.raises(KeyError):
+            s.astype(dt5)
+
     def test_astype_generic_timestamp_deprecated(self):
         # see gh-15524
         data = [1]