BUG: User-facing AssertionError with add column to SparseDataFrame

doc/source/whatsnew/v0.25.0.rst

@@ -402,7 +402,7 @@ Sparse
 
 - Significant speedup in `SparseArray` initialization that benefits most operations, fixing performance regression introduced in v0.20.0 (:issue:`24985`)
 - Bug in :class:`SparseFrame` constructor where passing ``None`` as the data would cause ``default_fill_value`` to be ignored (:issue:`16807`)
--
+- Bug in `SparseDataFrame` when adding a column in which the length of values does not match length of index, ``AssertionError`` is raised instead of raising ``ValueError`` (:issue:`25484`)
 
 
 Other

pandas/core/sparse/frame.py

@@ -430,8 +430,8 @@ def sp_maker(x, index=None):
 
  elif isinstance(value, SparseArray):
  if len(value) != len(self.index):
- raise AssertionError('Length of values does not match '
-  'length of index')
+ raise ValueError('Length of values does not match '
+ 'length of index')
  clean = value
 
  elif hasattr(value, '__iter__'):
@@ -441,8 +441,8 @@ def sp_maker(x, index=None):
  clean = sp_maker(clean)
  else:
  if len(value) != len(self.index):
- raise AssertionError('Length of values does not match '
-  'length of index')
+ raise ValueError('Length of values does not match '
+ 'length of index')
  clean = sp_maker(value)
 
  # Scalar

pandas/tests/sparse/frame/test_frame.py

@@ -568,8 +568,9 @@ def _check_frame(frame, orig):
  assert len(frame['I'].sp_values) == N // 2
 
  # insert ndarray wrong size
- msg = "Length of values does not match length of index"
- with pytest.raises(AssertionError, match=msg):
+ # GH 25484
+ msg = 'Length of values does not match length of index'
+ with pytest.raises(ValueError, match=msg):
  frame['foo'] = np.random.randn(N - 1)
 
  # scalar value