rewrite property engine

Property class is gone; logic is now done with Layers, Stack and Filter

test/property/test_property_layer.py

@@ -0,0 +1,52 @@
+from owrx.property import PropertyLayer
+from unittest import TestCase
+from unittest.mock import Mock
+
+
+class PropertyLayerTest(TestCase):
+    def testKeyIsset(self):
+        pm = PropertyLayer()
+        self.assertFalse("some_key" in pm)
+
+    def testKeyError(self):
+        pm = PropertyLayer()
+        with self.assertRaises(KeyError):
+            x = pm["some_key"]
+
+    def testSubscription(self):
+        pm = PropertyLayer()
+        pm["testkey"] = "before"
+        mock = Mock()
+        pm.wire(mock.method)
+        pm["testkey"] = "after"
+        mock.method.assert_called_once_with("testkey", "after")
+
+    def testUnsubscribe(self):
+        pm = PropertyLayer()
+        pm["testkey"] = "before"
+        mock = Mock()
+        sub = pm.wire(mock.method)
+        pm["testkey"] = "between"
+        mock.method.assert_called_once_with("testkey", "between")
+
+        mock.reset_mock()
+        pm.unwire(sub)
+        pm["testkey"] = "after"
+        mock.method.assert_not_called()
+
+    def testContains(self):
+        pm = PropertyLayer()
+        pm["testkey"] = "value"
+        self.assertTrue("testkey" in pm)
+
+    def testDoesNotContain(self):
+        pm = PropertyLayer()
+        self.assertFalse("testkey" in pm)
+
+    def testSubscribeBeforeSet(self):
+        pm = PropertyLayer()
+        mock = Mock()
+        pm.wireProperty("testkey", mock.method)
+        mock.method.assert_not_called()
+        pm["testkey"] = "newvalue"
+        mock.method.assert_called_once_with("newvalue")