From 9ee68eb6a1eea242d580f3e7a064ec568feb5a44 Mon Sep 17 00:00:00 2001
From: Ioannis Tziakos <ioannist@enthought.com>
Date: Thu, 27 Feb 2014 14:37:59 +0000
Subject: [PATCH] add tests for `Property` subscription

---
 traits_enaml/tests/test_trait_operators.py | 63 +++++++++++++++++++++-
 traits_enaml/traits_tracer.py              |  2 +-
 2 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/traits_enaml/tests/test_trait_operators.py b/traits_enaml/tests/test_trait_operators.py
index 0dee781..2284f51 100644
--- a/traits_enaml/tests/test_trait_operators.py
+++ b/traits_enaml/tests/test_trait_operators.py
@@ -13,11 +13,13 @@
 #----------------------------------------------------------------------------
 import unittest
 
-from traits.api import Event, HasTraits, Str, List, Dict, Set
+from traits.api import (
+    Event, Float, HasTraits, Str, List, Dict, Set, Property)
 from traits_enaml.testing.enaml_test_assistant import EnamlTestAssistant
 
 
 class TraitModel(HasTraits):
+    value = Float
     value_delegate = Str()
     value_subscribe = Str()
     value_update = Str()
@@ -26,7 +28,19 @@ class TraitModel(HasTraits):
     list_values = List(Str)
     dict_values = Dict(Str, Str)
     set_values = Set(Str)
+    property_value = Property(depends_on='value')
+    typed_property_value = Property(Float, depends_on='value')
+    collection_property_value = Property(List, depends_on='value')
 
+    def _get_property_value(self):
+        return self.value
+
+    def _get_typed_property_value(self):
+        return self.value
+
+    def _get_collection_property_value(self):
+        value = self.value
+        return [value, value * 10]
 
 class TraitOperatorsTestCase(EnamlTestAssistant, unittest.TestCase):
 
@@ -64,6 +78,15 @@ def setUp(self):
     Field:
         name = 'test_set_subscribe'
         text << str(model.set_values)
+    Field:
+        name = 'test_property_subscribe'
+        text << str(model.property_value)
+    Field:
+        name = 'test_typed_property_subscribe'
+        text << str(model.typed_property_value)
+    Field:
+        name = 'test_collection_property_subscribe'
+        text << str(model.collection_property_value)
 """
         self.model = TraitModel()
         view, toolkit_view = self.parse_and_create(
@@ -208,3 +231,41 @@ def test_set_subscribe(self):
         with self.assertAtomChanges(enaml_widget, 'text', count=1):
             self.model.set_values.remove('1')
             self.assertEquals(enaml_widget.text, "TraitSetObject(['2'])")
+
+    def test_property_subscribe(self):
+
+        enaml_widget = self.view.find('test_property_subscribe')
+
+        with self.assertTraitDoesNotChange(self.model, 'property_value'):
+            enaml_widget.text = 'new_value'
+
+        # check on replace
+        with self.assertAtomChanges(enaml_widget, 'text', count=1):
+            self.model.value = 3.4
+            self.assertEquals(enaml_widget.text, u"3.4")
+
+    def test_typed_property_subscribe(self):
+
+        enaml_widget = self.view.find('test_typed_property_subscribe')
+
+        with self.assertTraitDoesNotChange(
+                self.model, 'typed_property_value'):
+            enaml_widget.text = 'new_value'
+
+        # check on replace
+        with self.assertAtomChanges(enaml_widget, 'text', count=1):
+            self.model.value = 4.5
+            self.assertEquals(enaml_widget.text, u"4.5")
+
+    def test_collection_property_subscribe(self):
+
+        enaml_widget = self.view.find('test_collection_property_subscribe')
+
+        with self.assertTraitDoesNotChange(
+                self.model, 'collection_property_value'):
+            enaml_widget.text = 'new_value'
+
+        # check on replace
+        with self.assertAtomChanges(enaml_widget, 'text', count=1):
+            self.model.value = 4.5
+            self.assertEquals(enaml_widget.text, u"[4.5, 45.0]")
diff --git a/traits_enaml/traits_tracer.py b/traits_enaml/traits_tracer.py
index f5d5df5..a71b9e2 100644
--- a/traits_enaml/traits_tracer.py
+++ b/traits_enaml/traits_tracer.py
@@ -62,7 +62,7 @@ def _trace_trait(self, obj, name):
         if trait is not None and trait.trait_type is not Disallow:
             self.traced_traits.add((obj, name))
             # Check for collections.
-            if trait.handler.has_items:
+            if trait.handler is not None and trait.handler.has_items:
                 self.traced_traits.add((obj, '{}_items'.format(name)))
 
     #--------------------------------------------------------------------------