Exposing isDropAnimating in Draggable Snapshot (#559)

README.md

@@ -1220,7 +1220,12 @@ const myOnMouseDown = event => console.log('mouse down on', event.target);
 
 ```js
 type DraggableStateSnapshot = {|
+  // True, if Draggable is being dragged 
   isDragging: boolean,
+  // True, if Draggable is dropped and animated to its final position.
+  // Not always flipped to `true` when dropped, for example keyboard interaction or perfectly positioned drop 
+  // does not initiate animation
+  isDropAnimating: boolean,
   // What Droppable (if any) the Draggable is currently over
   draggingOver: ?DroppableId,
 |};
@@ -1349,6 +1354,7 @@ type DraggableProvided = {|
 
 type DraggableStateSnapshot = {|
   isDragging: boolean,
+  isDropAnimating: boolean,
   draggingOver: ?DroppableId,
 |};
 

src/view/draggable/draggable-types.js

@@ -72,6 +72,7 @@ export type Provided = {|
 
 export type StateSnapshot = {|
   isDragging: boolean,
+  isDropAnimating: boolean,
   draggingOver: ?DroppableId,
 |};
 

src/view/draggable/draggable.jsx

@@ -301,6 +301,7 @@ export default class Draggable extends Component<Props> {
       draggingOver: ?DroppableId,
     ): StateSnapshot => ({
       isDragging: isDragging || isDropAnimating,
+      isDropAnimating: isDropAnimating,
       draggingOver,
     }),
   );

test/unit/view/drag-drop-context/error-handling.spec.js

@@ -98,6 +98,7 @@ it('should reset the application state and swallow the exception if an invariant
   const expected: DraggableStateSnapshot = {
     draggingOver: null,
     isDragging: false,
+    isDropAnimating: false,
   };
   // no longer dragging
   expect(willThrough.props().snapshot).toEqual(expected);
@@ -123,6 +124,7 @@ it('should not reset the application state an exception occurs and throw it', ()
   const expected: DraggableStateSnapshot = {
     draggingOver: null,
     isDragging: false,
+    isDropAnimating: false,
   };
   // no longer dragging
   expect(willThrough.props().snapshot).toEqual(expected);

test/unit/view/unconnected-draggable.spec.js

@@ -1135,6 +1135,23 @@ describe('Draggable - unconnected', () => {
         const snapshot: StateSnapshot = getLastCall(myMock)[0].snapshot;
         expect(snapshot.draggingOver).toBe(null);
       });
+
+      it('should let consumers know if drop animation is in progress', () => {
+        const mapProps: MapProps = {
+          ...draggingMapProps,
+          isDropAnimating: true,
+        };
+
+        const myMock = jest.fn();
+
+        mountDraggable({
+          mapProps,
+          WrappedComponent: getStubber(myMock),
+        });
+
+        const snapshot: StateSnapshot = getLastCall(myMock)[0].snapshot;
+        expect(snapshot.isDropAnimating).toBe(true);
+      });
     });
 
     describe('drop animating', () => {