Tests that are checking that _grid_search method throws correct ValueError have been added.

Author: b0noI

sklearn/grid_search.py

@@ -332,11 +332,11 @@ def _check_param_grid(param_grid):
 
             check = [isinstance(v, k) for k in (list, tuple, np.ndarray)]
             if True not in check:
-                raise ValueError("Parameter values for parameter ({}) need to "
+                raise ValueError("Parameter values for parameter ({0}) need to "
                                  "be a sequence.".format(name))
 
             if len(v) == 0:
-                raise ValueError("Parameter values for parameter ({}) need to "
+                raise ValueError("Parameter values for parameter ({0}) need to "
                                  "be a non-empty sequence.".format(name))
 
 

sklearn/model_selection/_search.py

@@ -333,11 +333,11 @@ def _check_param_grid(param_grid):
 
             check = [isinstance(v, k) for k in (list, tuple, np.ndarray)]
             if True not in check:
-                raise ValueError("Parameter values for parameter ({}) need to "
+                raise ValueError("Parameter values for parameter ({0}) need to "
                                  "be a sequence.".format(name))
 
             if len(v) == 0:
-                raise ValueError("Parameter values for parameter ({}) need to "
+                raise ValueError("Parameter values for parameter ({0}) need to "
                                  "be a non-empty sequence.".format(name))
 
 

sklearn/model_selection/tests/test_search.py

@@ -165,6 +165,24 @@ def test_grid_search():
     assert_raises(ValueError, grid_search.fit, X, y)
 
 
+def test_grid_search_incorrect_param_grid():
+    assert_raise_message(
+        ValueError,
+        "Parameter values for parameter (C) need to be a sequence.",
+        GridSearchCV,
+        None,
+        {'C': 1})
+
+
+def test_grid_search_incorrect_param_grid():
+    assert_raise_message(
+        ValueError,
+        "Parameter values for parameter (C) need to be a non-empty sequence.",
+        GridSearchCV,
+        None,
+        {'C': []})
+
+
 @ignore_warnings
 def test_grid_search_no_score():
     # Test grid-search on classifier that has no score function.