[automerge] Don't reset the document

Author: jamesgpearce

src/persisters/persister-automerge/index.ts

@@ -10,6 +10,7 @@ import {
   objGet,
   objHas,
   objIsEmpty,
+  objNew,
   objSize,
   objToArray,
 } from '../../common/obj.ts';
@@ -135,7 +136,7 @@ export const createAutomergePersister = ((
   docObjName = TINYBASE,
   onIgnoredError?: (error: any) => void,
 ): AutomergePersister => {
-  docHandle.change((doc: any) => (doc[docObjName] = {}));
+  docHandle.change((doc: any) => objEnsure(doc, docObjName, objNew));
 
   const getPersisted = async (): Promise<Content | undefined> => {
     const doc = await docHandle.doc();

test/unit/persisters/persister-automerge.test.ts

@@ -101,6 +101,16 @@ describe('Load from doc', () => {
     await persister1.load();
     expect(store1.getContent()).toEqual([{t1: {r1: {c1: 1}}}, {v1: 1}]);
   });
+
+  test('persister after data', async () => {
+    docHandler1.change(
+      (doc: any) => (doc['tinybase'] = {t: {t1: {r1: {c1: 1}}}, v: {v1: 1}}),
+    );
+    const store2 = createStore();
+    const persister2 = createAutomergePersister(store2, docHandler1);
+    await persister2.load();
+    expect(store2.getContent()).toEqual([{t1: {r1: {c1: 1}}}, {v1: 1}]);
+  });
 });
 
 describe('Two stores, one doc', () => {