feat(modeling): add subprocess with start event included

When:

1. Creating expanded subprocess from palette.
2. Replacing task with expanded subprocess.

lib/features/modeling/behavior/SubProcessStartEventBehavior.js

@@ -0,0 +1,69 @@
+import inherits from 'inherits';
+
+import CommandInterceptor from 'diagram-js/lib/command/CommandInterceptor';
+
+import { is } from '../../../util/ModelUtil';
+import { isExpanded } from '../../../util/DiUtil.js';
+
+/**
+ * Add start event child by default when creating an expanded subprocess
+ * with create.start or replacing a task with an expanded subprocess.
+ */
+export default function SubProcessStartEventBehavior(eventBus, modeling) {
+  CommandInterceptor.call(this, eventBus);
+
+  eventBus.on('create.start', function(event) {
+    var shape = event.context.shape,
+        hints = event.context.hints;
+
+    hints.shouldAddStartEvent = is(shape, 'bpmn:SubProcess') && isExpanded(shape);
+  });
+
+  this.postExecuted('shape.create', function(event) {
+    var shape = event.context.shape,
+        hints = event.context.hints,
+        position;
+
+    if (!hints.shouldAddStartEvent) {
+      return;
+    }
+
+    position = calculatePositionRelativeToShape(shape);
+
+    modeling.createShape({ type: 'bpmn:StartEvent' }, position, shape);
+  });
+
+  this.postExecuted('shape.replace', function(event) {
+    var oldShape = event.context.oldShape,
+        newShape = event.context.newShape,
+        position;
+
+    if (
+      !is(newShape, 'bpmn:SubProcess') ||
+      !is(oldShape, 'bpmn:Task') ||
+      !isExpanded(newShape)
+    ) {
+      return;
+    }
+
+    position = calculatePositionRelativeToShape(newShape);
+
+    modeling.createShape({ type: 'bpmn:StartEvent' }, position, newShape);
+  });
+}
+
+SubProcessStartEventBehavior.$inject = [
+  'eventBus',
+  'modeling'
+];
+
+inherits(SubProcessStartEventBehavior, CommandInterceptor);
+
+// helpers //////////
+
+function calculatePositionRelativeToShape(shape) {
+  return {
+    x: shape.x + shape.width / 6,
+    y: shape.y + shape.height / 2
+  };
+}

lib/features/modeling/behavior/index.js

@@ -20,6 +20,7 @@ import RemoveParticipantBehavior from './RemoveParticipantBehavior';
 import ReplaceElementBehaviour from './ReplaceElementBehaviour';
 import ResizeLaneBehavior from './ResizeLaneBehavior';
 import RemoveElementBehavior from './RemoveElementBehavior';
+import SubProcessStartEventBehavior from './SubProcessStartEventBehavior';
 import ToggleElementCollapseBehaviour from './ToggleElementCollapseBehaviour';
 import UnclaimIdBehavior from './UnclaimIdBehavior';
 import UpdateFlowNodeRefsBehavior from './UpdateFlowNodeRefsBehavior';
@@ -50,6 +51,7 @@ export default {
     'replaceElementBehaviour',
     'resizeLaneBehavior',
     'toggleElementCollapseBehaviour',
+    'subProcessStartEventBehavior',
     'unclaimIdBehavior',
     'unsetDefaultFlowBehavior',
     'updateFlowNodeRefsBehavior'
@@ -77,6 +79,7 @@ export default {
   resizeLaneBehavior: [ 'type', ResizeLaneBehavior ],
   removeElementBehavior: [ 'type', RemoveElementBehavior ],
   toggleElementCollapseBehaviour : [ 'type', ToggleElementCollapseBehaviour ],
+  subProcessStartEventBehavior: [ 'type', SubProcessStartEventBehavior ],
   unclaimIdBehavior: [ 'type', UnclaimIdBehavior ],
   updateFlowNodeRefsBehavior: [ 'type', UpdateFlowNodeRefsBehavior ],
   unsetDefaultFlowBehavior: [ 'type', UnsetDefaultFlowBehavior ]

test/spec/features/modeling/behavior/SubProcessBehavior.start-event.bpmn

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" id="Definitions_007va6i" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="3.2.0-dev">
+  <bpmn:process id="Process_1giw3j5" isExecutable="true">
+    <bpmn:task id="Task_1" />
+    <bpmn:subProcess id="SubProcess_1" />
+  </bpmn:process>
+  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
+    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_1giw3j5">
+      <bpmndi:BPMNShape id="Task_07xra8r_di" bpmnElement="Task_1">
+        <dc:Bounds x="156" y="81" width="100" height="80" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="SubProcess_01nq2r1_di" bpmnElement="SubProcess_1" isExpanded="true">
+        <dc:Bounds x="160" y="280" width="350" height="200" />
+      </bpmndi:BPMNShape>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn:definitions>

test/spec/features/modeling/behavior/SubProcessStartEventBehaviorSpec.js

@@ -0,0 +1,127 @@
+import {
+  bootstrapModeler,
+  inject
+} from 'test/TestHelper';
+
+import coreModule from 'lib/core';
+import createModule from 'diagram-js/lib/features/create';
+import draggingModule from 'diagram-js/lib/features/create';
+import modelingModule from 'lib/features/modeling';
+import replaceModule from 'lib/features/replace';
+
+import { is } from 'lib/util/ModelUtil';
+import { createCanvasEvent as canvasEvent } from 'test/util/MockEvents';
+
+describe('features/modeling/behavior - subprocess start event', function() {
+
+  var diagramXML = require('./SubProcessBehavior.start-event.bpmn');
+
+  beforeEach(bootstrapModeler(diagramXML, {
+    modules: [
+      coreModule,
+      createModule,
+      draggingModule,
+      modelingModule,
+      replaceModule
+    ]
+  }));
+
+
+  describe('create', function() {
+
+    it('should contain start event child', inject(
+      function(canvas, elementFactory, create, dragging) {
+
+        // given
+        var rootElement = canvas.getRootElement(),
+            subProcess = elementFactory.createShape({
+              type: 'bpmn:SubProcess',
+              isExpanded: true
+            }),
+            startEvents;
+
+        // when
+        create.start(canvasEvent({ x: 0, y: 0 }), subProcess);
+
+        dragging.hover({ element: rootElement });
+
+        dragging.move(canvasEvent({ x: 600, y: 150 }));
+
+        dragging.end();
+
+        // then
+        startEvents = getChildStartEvents(subProcess);
+
+        expect(startEvents).to.have.length(1);
+      }
+    ));
+
+  });
+
+
+  describe('replace', function() {
+
+    describe('task -> expanded subprocess', function() {
+
+      it('should add start event child to subprocess', inject(
+        function(elementRegistry, bpmnReplace) {
+
+          // given
+          var task = elementRegistry.get('Task_1'),
+              expandedSubProcess,
+              startEvents;
+
+          // when
+          expandedSubProcess = bpmnReplace.replaceElement(task, {
+            type: 'bpmn:SubProcess',
+            isExpanded: true
+          });
+
+          // then
+          startEvents = getChildStartEvents(expandedSubProcess);
+
+          expect(startEvents).to.have.length(1);
+        }
+      ));
+
+    });
+
+
+    describe('task -> collapsed subprocess', function() {
+
+      it('should NOT add start event child to subprocess', inject(
+        function(elementRegistry, bpmnReplace) {
+
+          // given
+          var task = elementRegistry.get('Task_1'),
+              collapsedSubProcess,
+              startEvents;
+
+          // when
+          collapsedSubProcess = bpmnReplace.replaceElement(task, {
+            type: 'bpmn:SubProcess',
+            isExpanded: false
+          });
+
+          // then
+          startEvents = getChildStartEvents(collapsedSubProcess);
+
+          expect(startEvents).to.have.length(0);
+        }
+      ));
+
+    });
+
+  });
+
+});
+
+// helpers //////////
+
+function isStartEvent(element) {
+  return is(element, 'bpmn:StartEvent');
+}
+
+function getChildStartEvents(element) {
+  return element.children.filter(isStartEvent);
+}