BUG: #14095. Amend eval() resolvers kwarg to accept lists

Author: tom-bird

doc/source/whatsnew/v0.19.0.txt

@@ -1290,3 +1290,4 @@ Bug Fixes
 - Bug in ``.to_string()`` when called with an integer ``line_width`` and ``index=False`` raises an UnboundLocalError exception because ``idx`` referenced before assignment.
 
 - Bug in ``read_csv()``, where aliases for utf-xx (e.g. UTF-xx, UTF_xx, utf_xx) raised UnicodeDecodeError (:issue:`13549`)
+- Bug in ``eval()`` where the ``resolvers`` argument would not accept a list (:issue`14095`)

pandas/core/frame.py

@@ -2266,7 +2266,7 @@ def eval(self, expr, inplace=None, **kwargs):
             resolvers = dict(self.iteritems()), index_resolvers
         if 'target' not in kwargs:
             kwargs['target'] = self
-        kwargs['resolvers'] = kwargs.get('resolvers', ()) + resolvers
+        kwargs['resolvers'] = kwargs.get('resolvers', ()) + tuple(resolvers)
         return _eval(expr, inplace=inplace, **kwargs)
 
     def select_dtypes(self, include=None, exclude=None):

pandas/tests/frame/test_query_eval.py

@@ -147,6 +147,12 @@ def test_query_non_str(self):
         with tm.assertRaisesRegexp(ValueError, msg):
             df.query(111)
 
+    def test_eval_resolvers_as_list(self):
+        df = DataFrame(randn(10, 2), columns=list('ab'))
+        dict1 = {'a': 1}
+        dict2 = {'b': 2}
+        self.assertTrue(df.eval('a + b', resolvers=[dict1, dict2]) == dict1['a'] + dict2['b'])
+
 
 class TestDataFrameQueryWithMultiIndex(tm.TestCase):