Add a simple sanity test for pydot outputting

Depends-On: Ia633ccd1dca94f70b05ae4376a1c3a3f252a9923

Related-Bug: #1561656

Change-Id: I930a1ee9c1d17a12328d920bbe02ea0b77947295

taskflow/tests/unit/test_types.py

@@ -98,6 +98,29 @@ class GraphTest(test.TestCase):
         g3 = graph.merge_graphs(g, g2)
         self.assertEqual(3, len(g3))
 
+    def test_pydot_output(self):
+        # NOTE(harlowja): ensure we use the ordered types here, otherwise
+        # the expected output will vary based on randomized hashing and then
+        # the test will fail randomly...
+        for graph_cls, kind, edge in [(graph.OrderedDiGraph, 'digraph', '->'),
+                                      (graph.OrderedGraph, 'graph', '--')]:
+            g = graph_cls(name='test')
+            g.add_node("a")
+            g.add_node("b")
+            g.add_node("c")
+            g.add_edge("a", "b")
+            g.add_edge("b", "c")
+            expected = """
+strict %(kind)s "test" {
+a;
+b;
+c;
+a %(edge)s b;
+b %(edge)s c;
+}
+""" % ({'kind': kind, 'edge': edge})
+            self.assertEqual(expected.lstrip(), g.export_to_dot())
+
     def test_merge_edges(self):
         g = graph.DiGraph()
         g.add_node("a")

taskflow/types/graph.py

@@ -115,7 +115,7 @@ class DiGraph(nx.DiGraph):
 
     def export_to_dot(self):
         """Exports the graph to a dot format (requires pydot library)."""
-        return nx.to_pydot(self).to_string()
+        return nx_pydot.to_pydot(self).to_string()
 
     def is_directed_acyclic(self):
         """Returns if this graph is a DAG or not."""
@@ -157,8 +157,20 @@ class DiGraph(nx.DiGraph):
 class OrderedDiGraph(DiGraph):
     """A directed graph subclass with useful utility functions.
 
-    This derivative retains node, edge, insertation and iteration
-    ordering (so that the iteration order matches the insertation
+    This derivative retains node, edge, insertion and iteration
+    ordering (so that the iteration order matches the insertion
+    order).
+    """
+    node_dict_factory = collections.OrderedDict
+    adjlist_dict_factory = collections.OrderedDict
+    edge_attr_dict_factory = collections.OrderedDict
+
+
+class OrderedGraph(Graph):
+    """A graph subclass with useful utility functions.
+
+    This derivative retains node, edge, insertion and iteration
+    ordering (so that the iteration order matches the insertion
     order).
     """
     node_dict_factory = collections.OrderedDict

test-requirements.txt

@@ -21,6 +21,9 @@ kazoo>=2.2 # Apache-2.0
 # Used for testing redis jobboards
 redis>=2.10.0 # MIT
 
+# Used for making sure pydot is still working
+pydotplus>=2.0.2 # MIT License
+
 # Used for testing database persistence backends.
 SQLAlchemy<1.1.0,>=1.0.10 # MIT
 alembic>=0.8.0 # MIT