added test for overwriting of graphs with using keywords

graphi_unittests/types_unittests/test_adjacency_graph.py

@@ -8,6 +8,7 @@
 import graphi.types.adjacency_graph
 import graphi.abc
 from graphi import operators
+from graphi.types.decorator import undirectable
 
 from . import _graph_interface_mixins as mixins
 
@@ -16,6 +17,32 @@ class TestAdjacencyGraphInterface(mixins.Mixin.GraphInitMixin, mixins.Mixin.Grap
     graph_cls = graphi.types.adjacency_graph.AdjacencyGraph
 
 
+@undirectable
+class DistanceGraph(graphi.types.adjacency_graph.AdjacencyGraph):
+    def __init__(self, *source, distance=lambda *args: 1, **kwargs):
+        self.distance = distance
+        super(DistanceGraph, self).__init__(*source, **kwargs)
+
+    def __getitem__(self, item):
+        if isinstance(item, slice):
+            assert item.step is None, '%s does not support stride argument for edges' % self.__class__.__name__
+            node_from, node_to = item.start, item.stop
+            if node_from not in self._adjacency:
+                raise graphi.abc.EdgeError  # first edge node
+            elif node_to not in self._adjacency:
+                raise graphi.abc.EdgeError  # second edge node
+            # Since we don't know the type of nodes, we cannot test
+            # node_to > node_from to detect swapped pairs. Since we
+            # *do* store nodes in a `set`, they must support hash.
+            if self.undirected and hash(node_to) > hash(node_from):
+                node_to, node_from = node_from, node_to
+            return self.distance(node_from, node_to)
+        else:
+            if item not in self:
+                raise graphi.abc.NodeError
+            return {candidate: self[item:candidate] for candidate in self if candidate != item}
+
+
 class TestAdjacencyGraph(unittest.TestCase):
     # distance graph class to test
     graph_cls = graphi.types.adjacency_graph.AdjacencyGraph
@@ -316,3 +343,8 @@ def test_value_view_directed(self):
             self.assertTrue(value in value_view)
         self.assertFalse(3 in value_view)
         self.assertEqual(len(nodes) * 2, len(value_view))
+
+    def test_graph_customisation(self):
+        graph = DistanceGraph([1, 2], undirected=True)
+        self.assertEquals(1, graph[1:2])
+        self.assertEquals(1, graph.distance(1, 2))