Added test

IPython/utils/tests/test_traitlets.py

@@ -367,29 +367,29 b' class TestHasTraitsNotify(TestCase):'
 
         class A(HasTraits):
             listen_to = ['a']
-            
+
             a = Int(0)
             b = 0
-            
+
             def __init__(self, **kwargs):
                 super(A, self).__init__(**kwargs)
                 self.on_trait_change(self.listener1, ['a'])
-            
+
             def listener1(self, name, old, new):
                 self.b += 1
 
         class B(A):
-                    
+
             c = 0
             d = 0
-            
+
             def __init__(self, **kwargs):
                 super(B, self).__init__(**kwargs)
                 self.on_trait_change(self.listener2)
-            
+
             def listener2(self, name, old, new):
                 self.c += 1
-            
+
             def _a_changed(self, name, old, new):
                 self.d += 1
 
@@ -455,7 +455,7 b' class TestHasTraits(TestCase):'
             def __init__(self, i):
                 super(A, self).__init__()
                 self.i = i
-        
+
         a = A(5)
         self.assertEqual(a.i, 5)
         # should raise TypeError if no positional arg given
@@ -888,12 +888,31 b' class TestList(TraitTestBase):'
     _default_value = []
     _good_values = [[], [1], list(range(10)), (1,2)]
     _bad_values = [10, [1,'a'], 'a']
-    
+
     def coerce(self, value):
         if value is not None:
             value = list(value)
         return value
 
+class Foo(object):
+    pass
+
+class InstanceListTrait(HasTraits):
+
+    value = List(Instance(__name__+'.Foo'))
+
+class TestInstanceList(TraitTestBase):
+
+    obj = InstanceListTrait()
+
+    def test_klass(self):
+        """Test that the instance klass is properly assigned."""
+        self.assertIs(self.obj.traits()['value']._trait.klass, Foo)
+
+    _default_value = []
+    _good_values = [[Foo(), Foo(), None], None]
+    _bad_values = [['1', 2,], '1', [Foo]]
+
 class LenListTrait(HasTraits):
 
     value = List(Int, [0], minlen=1, maxlen=2)
@@ -1067,7 +1086,7 b' class TestLink(TestCase):'
             count = Int()
         a = A(value=9)
         b = B(count=8)
-        
+
         # Register callbacks that count.
         callback_count = []
         def a_callback(name, old, new):