TypeErrors should be raised for invalid input types, rather than ValueErrors.

Author: pletchm

xarray/core/dataarray.py

@@ -1172,7 +1172,7 @@ def expand_dims(self, dim=None, axis=None, **dim_kwargs):
             This object, but with an additional dimension(s).
         """
         if isinstance(dim, int):
-            raise ValueError('dim should be str or sequence of strs or dict')
+            raise TypeError('dim should be str or sequence of strs or dict')
         elif isinstance(dim, str):
             dim = {dim: 1}
         elif isinstance(dim, (list, tuple)):

xarray/core/dataset.py

@@ -2362,7 +2362,7 @@ def expand_dims(self, dim=None, axis=None, **dim_kwargs):
             This object, but with an additional dimension(s).
         """
         if isinstance(dim, int):
-            raise ValueError('dim should be str or sequence of strs or dict')
+            raise TypeError('dim should be str or sequence of strs or dict')
         elif isinstance(dim, str):
             dim = {dim: 1}
         elif isinstance(dim, (list, tuple)):
@@ -2404,8 +2404,8 @@ def expand_dims(self, dim=None, axis=None, **dim_kwargs):
             elif isinstance(v, int):
                 pass  # Do nothing if the dimensions value is just an int
             else:
-                raise ValueError('The value of new dimension {k} must be '
-                                 'an iterable or an int'.format(k=k))
+                raise TypeError('The value of new dimension {k} must be '
+                                'an iterable or an int'.format(k=k))
 
         for k, v in self._variables.items():
             if k not in dim:

xarray/tests/test_dataarray.py

@@ -1303,7 +1303,7 @@ def test_expand_dims_error(self):
                           coords={'x': np.linspace(0.0, 1.0, 3)},
                           attrs={'key': 'entry'})
 
-        with raises_regex(ValueError, 'dim should be str or'):
+        with raises_regex(TypeError, 'dim should be str or'):
             array.expand_dims(0)
         with raises_regex(ValueError, 'lengths of dim and axis'):
             # dims and axis argument should be the same length
@@ -1331,7 +1331,7 @@ def test_expand_dims_error(self):
         array = DataArray(np.random.randn(3, 4), dims=['x', 'dim_0'],
                           coords={'x': np.linspace(0.0, 1.0, 3)},
                           attrs={'key': 'entry'})
-        with pytest.raises(ValueError):
+        with pytest.raises(TypeError):
             array.expand_dims({"new_dim": 3.2})
 
         # Attempt to use both dim and kwargs

xarray/tests/test_dataset.py

@@ -2020,7 +2020,7 @@ def test_expand_dims_error(self):
                                    'b': np.linspace(0, 1, 4),
                                    'c': np.linspace(0, 1, 5)},
                            attrs={'key': 'entry'})
-        with raises_regex(ValueError, 'value of new dimension'):
+        with raises_regex(TypeError, 'value of new dimension'):
             original.expand_dims({"d": 3.2})
 
         with raises_regex(ValueError, 'both keyword and positional'):