Expose getInitialSnapshot (#4731)

* Expose getInitialSnapshot

* Add more details to changeset

* Add words

.changeset/clean-brooms-yell.md

@@ -0,0 +1,16 @@
+---
+'xstate': patch
+---
+
+You can now import `getInitialSnapshot(…)` from `xstate` directly, which is useful for getting a mock of the initial snapshot when interacting with machines (or other actor logic) without `createActor(…)`:
+
+```ts
+import { getInitialSnapshot } from 'xstate';
+import { someMachine } from './someMachine';
+
+// Returns the initial snapshot (state) of the machine
+const initialSnapshot = getInitialSnapshot(
+  someMachine,
+  { name: 'Mateusz' } // optional input
+);
+```

packages/core/src/index.ts

@@ -9,7 +9,7 @@ export * from './typegenTypes.ts';
 export * from './types.ts';
 export { waitFor } from './waitFor.ts';
 import { createMachine } from './createMachine.ts';
-export { getNextSnapshot } from './getNextSnapshot.ts';
+export { getNextSnapshot, getInitialSnapshot } from './getNextSnapshot.ts';
 import { Actor, createActor, interpret, Interpreter } from './createActor.ts';
 import { StateNode } from './StateNode.ts';
 // TODO: decide from where those should be exported

packages/core/test/deterministic.test.ts

@@ -1,6 +1,10 @@
-import { fromCallback, createActor, getNextSnapshot } from '../src/index.ts';
-import { createMachine } from '../src/createMachine.ts';
-import { getInitialSnapshot } from '../src/getNextSnapshot.ts';
+import {
+  fromCallback,
+  createActor,
+  getNextSnapshot,
+  createMachine,
+  getInitialSnapshot
+} from '../src/index.ts';
 
 describe('deterministic machine', () => {
   const lightMachine = createMachine({

packages/core/test/getNextSnapshot.test.ts

@@ -1,10 +1,9 @@
 import {
-  createActor,
   createMachine,
   fromTransition,
-  getNextSnapshot
+  getNextSnapshot,
+  getInitialSnapshot
 } from '../src';
-import { getInitialSnapshot } from '../src/getNextSnapshot';
 
 describe('getNextSnapshot', () => {
   it('should calculate the next snapshot for transition logic', () => {

packages/core/test/id.test.ts

@@ -1,6 +1,10 @@
 import { testAll } from './utils';
-import { createMachine, createActor } from '../src/index.ts';
-import { getInitialSnapshot, getNextSnapshot } from '../src/getNextSnapshot.ts';
+import {
+  createMachine,
+  createActor,
+  getNextSnapshot,
+  getInitialSnapshot
+} from '../src/index.ts';
 
 const idMachine = createMachine({
   initial: 'A',