[core] Restore from persisted snapshot

packages/core/src/actions/spawnChild.ts

@@ -40,13 +40,15 @@
     systemId,
     src,
     input,
-    syncSnapshot
+    syncSnapshot,
+    snapshot: persistedSnapshot
   }: {
     id: ResolvableActorId<MachineContext, EventObject, EventObject, string>;
     systemId: string | undefined;
     src: AnyActorLogic | string;
     input?: unknown;
     syncSnapshot: boolean;
+    snapshot?: any;
   }
 ) {
   const logic =
@@ -63,6 +65,7 @@
       src,
       parent: actorScope.self,
       syncSnapshot,
+      snapshot: persistedSnapshot,
       systemId,
       input:
         typeof input === 'function'
@@ -171,6 +174,7 @@
         systemId?: string;
         input?: unknown;
         syncSnapshot?: boolean;
+        snapshot?: any;
       }
     ];
 
@@ -183,7 +187,7 @@
 >(
   ...[
     src,
-    { id, systemId, input, syncSnapshot = false } = {} as any
+    { id, systemId, input, syncSnapshot = false, snapshot } = {} as any
   ]: SpawnArguments<TContext, TExpressionEvent, TEvent, TActor>
 ): SpawnAction<TContext, TExpressionEvent, TParams, TEvent, TActor> {
   function spawnChild(
@@ -201,6 +205,7 @@
   spawnChild.src = src;
   spawnChild.input = input;
   spawnChild.syncSnapshot = syncSnapshot;
+  spawnChild.snapshot = snapshot;
 
   spawnChild.resolve = resolveSpawn;
   spawnChild.execute = executeSpawn;

packages/core/src/spawn.ts

@@ -57,6 +57,7 @@ export type Spawner<TActor extends ProvidedActor> = IsLiteralString<
         systemId?: string;
         input?: TLogic extends string ? unknown : InputFrom<TLogic>;
         syncSnapshot?: boolean;
+        snapshot?: any;
       }
     ) => TLogic extends string ? AnyActorRef : ActorRefFrom<TLogic>;
 
@@ -67,7 +68,7 @@ export function createSpawner(
   spawnedChildren: Record<string, AnyActorRef>
 ): Spawner<any> {
   const spawn: Spawner<any> = (src, options = {}) => {
-    const { systemId, input } = options;
+    const { systemId, input, snapshot } = options;
     if (typeof src === 'string') {
       const logic = resolveReferencedActor(machine, src);
 
@@ -90,7 +91,8 @@ export function createSpawner(
               })
             : input,
         src,
-        systemId
+        systemId,
+        snapshot
       }) as any;
 
       spawnedChildren[actorRef.id] = actorRef;

packages/core/test/spawnChild.test.ts

@@ -5,6 +5,7 @@ import {
   createMachine,
   fromObservable,
   fromPromise,
+  fromTransition,
   sendTo,
   spawnChild
 } from '../src';
@@ -112,4 +113,25 @@ describe('spawnChild action', () => {
 
     expect(spy).toHaveBeenCalledTimes(1);
   });
+
+  it('can restore from a persisted snapshot', () => {
+    const countLogic = fromTransition((s) => s, 0);
+
+    const actor = createActor(
+      createMachine({
+        entry: spawnChild(countLogic, {
+          id: 'child',
+          snapshot: {
+            context: 100
+          }
+        })
+      })
+    );
+
+    actor.start();
+
+    expect(actor.getSnapshot().children.child.getSnapshot().context).toEqual(
+      100
+    );
+  });
 });