Merge pull request #486 from athossampayo/test_tabble_apply

Added ValueError testing for util.table_apply as asked in issue #476

tests/test_util.py

@@ -3,6 +3,7 @@
 import datascience as ds
 from datascience import util
 import numpy as np
+import pytest
 
 def test_doctests():
     results = doctest.testmod(util, optionflags=doctest.NORMALIZE_WHITESPACE)
@@ -50,6 +51,10 @@ def test_table_apply():
     assert all(newtab['a'] == tab['a'])
     assert all(newtab['b'] == tab['b'] + 1)
 
+    with pytest.raises(ValueError) as err:
+        util.table_apply(tab, lambda a: a+1, subset=['b', 'd'])
+        assert "Colum mismatch: ['d']" in str(err.value)
+
 
 def _round_eq(a, b):
     if hasattr(a, '__len__'):