Add labels for exit conditions to edges between nodes

routemaster/config/model.py

@@ -1,6 +1,7 @@
 """Loading and validation of config files."""
 
 import datetime
+import collections
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -103,6 +104,10 @@ def all_destinations(self) -> Collection[str]:
         """Returns the constant next state."""
         return [self.state]
 
+    def destinations_for_render(self) -> Mapping[str, str]:
+        """Returns the constant next state."""
+        return {self.state: ""}
+
 
 class ContextNextStatesOption(NamedTuple):
     """Represents an option for a context conditional next state."""
@@ -128,6 +133,30 @@ def all_destinations(self) -> Collection[str]:
         """Returns all possible destination states."""
         return [x.state for x in self.destinations] + [self.default]
 
+    def destinations_for_render(self) -> Mapping[str, str]:
+        """
+        Returns destination states and a summary of how each might be reached.
+
+        This is intended for use in visualisations, so while the description of
+        how to reach each state is somewhat Pythonic its focus is being
+        human-readable.
+        """
+        destination_reasons = [
+            (x.state, f"{self.path} == {x.value}")
+            for x in self.destinations
+        ] + [
+            (self.default, "default"),
+        ]
+
+        collected = collections.defaultdict(list)
+        for destination, raeson in destination_reasons:
+            collected[destination].append(raeson)
+
+        return {
+            destination: " or ".join(reasons)
+            for destination, reasons in collected.items()
+        }
+
 
 class NoNextStates(NamedTuple):
     """Represents the lack of a next state to progress to."""
@@ -142,6 +171,10 @@ def all_destinations(self) -> Collection[str]:
         """Returns no states."""
         return []
 
+    def destinations_for_render(self) -> Mapping[str, str]:
+        """Returns no states."""
+        return {}
+
 
 NextStates = Union[ConstantNextState, ContextNextStates, NoNextStates]
 

routemaster/config/tests/test_next_states.py

@@ -11,12 +11,14 @@
 def test_constant_next_state():
     next_states = ConstantNextState(state='foo')
     assert next_states.all_destinations() == ['foo']
+    assert next_states.destinations_for_render() == {'foo': ""}
     assert next_states.next_state_for_label(None) == 'foo'
 
 
 def test_no_next_states_must_not_be_called():
     next_states = NoNextStates()
     assert next_states.all_destinations() == []
+    assert next_states.destinations_for_render() == {}
     with pytest.raises(RuntimeError):
         next_states.next_state_for_label(None)
 
@@ -34,6 +36,11 @@ def test_context_next_states(make_context):
     context = make_context(label='label1', metadata={'foo': True})
 
     assert next_states.all_destinations() == ['1', '2', '3']
+    assert next_states.destinations_for_render() == {
+        '1': "metadata.foo == True",
+        '2': "metadata.foo == False",
+        '3': "default",
+    }
     assert next_states.next_state_for_label(context) == '1'
 
 

routemaster/config/visualisation.jinja

@@ -128,8 +128,13 @@
             'target-arrow-shape': 'triangle',
             'target-arrow-color': '#ccc',
             'line-color': '#ccc',
+            'text-wrap': 'wrap',
+            'text-max-width': 80,
             'width': 1
           })
+          .style({
+            'label': 'data(label)',
+          })
         .selector(':selected')
           .css({
             'background-color': 'black',
@@ -157,7 +162,7 @@
       cy.layout(layoutOptions).run();
     }
 
-    var initialSpacingFactor = 0.4 + cy.nodes().length * 0.04;
+    var initialSpacingFactor = 0.5 + cy.nodes().length * 0.05;
     var spacingFactorElem = document.getElementById('spacing-factor');
     spacingFactorElem.addEventListener('change', function() {
         changeSpacing(spacingFactorElem.value / 10);

routemaster/state_machine/tests/test_visualisation.py

@@ -12,54 +12,47 @@
         'data': {
             'source': 'start',
             'target': 'perform_action',
+            'label': 'feeds.tests.should_do_alternate_action == False or default',
         },
     },
     {
         'data': {
             'source': 'start',
             'target': 'perform_alternate_action',
+            'label': 'feeds.tests.should_do_alternate_action == True',
         },
     },
-    # We emit duplicate edges when the destination is duplicated; this seems to
-    # be fine though.
     {
         'data': {
-            'source': 'start',
-            'target': 'perform_action',
+            'id': 'perform_action',
         },
-    },
-    {
-        'data': {'id': 'perform_action'},
         'classes': 'action',
     },
     {
         'data': {
             'source': 'perform_action',
             'target': 'end',
+            'label': '',
         },
     },
     {
-        'data': {'id': 'perform_alternate_action'},
+        'data': {
+            'id': 'perform_alternate_action',
+        },
         'classes': 'action',
     },
     {
         'data': {
             'source': 'perform_alternate_action',
             'target': 'end',
+            'label': 'feeds.tests.should_loop == False or default',
         },
     },
-    # We emit duplicate edges when the destination is duplicated; this seems to
-    # be fine though.
     {
         'data': {
             'source': 'perform_alternate_action',
             'target': 'start',
-        },
-    },
-    {
-        'data': {
-            'source': 'perform_alternate_action',
-            'target': 'end',
+            'label': 'feeds.tests.should_loop == True',
         },
     },
     {

routemaster/state_machine/visualisation.py

@@ -20,11 +20,12 @@ def nodes_for_cytoscape(
             'classes': node_kind,
         })
 
-        all_destinations = state.next_states.all_destinations()
-        for destination_name in all_destinations:
+        destinations = state.next_states.destinations_for_render()
+        for destination_name, reason in destinations.items():
             elements.append({'data': {
                 'source': state.name,
                 'target': destination_name,
+                'label': reason,
             }})
 
     return elements