Add docs and improve tests

Author: codingjoe

docs/core_components.rst

@@ -46,6 +46,7 @@ Advanced Workflow API
     :show-inheritance:
     :members:
         urls,
+        rankdir,
         get_graph_svg,
         get_instance_graph_svg,
         get_absolute_url,

joeflow/models.py

@@ -67,6 +67,7 @@ class Workflow(models.Model, metaclass=WorkflowBase):
     modified = models.DateTimeField(auto_now=True, db_index=True)
 
     rankdir = "LR"
+    """Direction of the workflow's graph visualization."""
 
     task_set = GenericRelation(
         "joeflow.Task", object_id_field="_workflow_id", for_concrete_model=False

tests/test_models.py

@@ -114,7 +114,7 @@ def test_get_graph(self, fixturedir):
     def test_change_graph_direction(self, fixturedir):
         workflows.SimpleWorkflow.rankdir = "TD"
         graph = workflows.SimpleWorkflow.get_graph()
-        assert isinstance(graph, Digraph)
+        assert 'rankdir=TD' in str(graph)
 
     def test_get_graph_svg(self, fixturedir):
         svg = workflows.SimpleWorkflow.get_graph_svg()