fix(colist): correct successor order when handling conflicts

.changeset/lovely-trainers-boil.md

@@ -0,0 +1,5 @@
+---
+"cojson": patch
+---
+
+fix(colist): correct successor order when handling conflicts

packages/cojson/src/coValues/coList.ts

@@ -320,9 +320,8 @@ export class RawCoListView<
           });
         }
 
-        // traverse successors in reverse for correct insertion behavior
-        for (const successor of entry.successors) {
-          todo.push(successor);
+        for (let i = entry.successors.length - 1; i >= 0; i--) {
+          todo.push(entry.successors[i]!);
         }
       }
     }
@@ -473,12 +472,6 @@ export class RawCoList<
       after: opIDBefore,
     }));
 
-    if (opIDBefore !== "start") {
-      // When added as successors we need to reverse the items
-      // to keep the same insertion order
-      changes.reverse();
-    }
-
     this.core.makeTransaction(changes, privacy);
 
     this.rebuildFromCore();

packages/cojson/src/tests/coList.test.ts

@@ -11,10 +11,8 @@ import {
 
 const Crypto = await WasmCrypto.create();
 
-let jazzCloud = setupTestNode({ isSyncServer: true });
-
 beforeEach(async () => {
-  jazzCloud = setupTestNode({ isSyncServer: true });
+  setupTestNode({ isSyncServer: true });
 });
 
 test("Empty CoList works", () => {
@@ -128,11 +126,11 @@ test("appendItems at index", () => {
   content.appendItems(["hello", "world"], 0, "trusting");
   expect(content.toJSON()).toEqual([
     "first",
-    "hello",
-    "world",
     "second",
     "third",
     "fourth",
+    "hello",
+    "world",
   ]);
 });
 
@@ -252,7 +250,7 @@ test("mixing prepend and append", () => {
   expect(list.toJSON()).toEqual([1, 2, 3]);
 });
 
-test.skip("Items appended to start", () => {
+test("Items appended to start", () => {
   const node = new LocalNode(...randomAnonymousAccountAndSessionID(), Crypto);
 
   const coValue = node.createCoValue({
@@ -271,7 +269,7 @@ test.skip("Items appended to start", () => {
   expect(content.toJSON()).toEqual(["first", "second", "third"]);
 });
 
-test.skip("syncing changes with an older timestamp", async () => {
+test("syncing appends with an older timestamp", async () => {
   const client = setupTestNode({
     connected: true,
   });
@@ -312,8 +310,59 @@ test.skip("syncing changes with an older timestamp", async () => {
   otherClient.connectToSyncServer();
 
   await waitFor(() => {
+    list.rebuildFromCore(); // TODO: This is a hack to ensure the list is rebuilt, we can remove it after the incremental processing lands
     expect(list.toJSON()).toEqual([1, 2, 3, 5, 4, 6]);
   });
 
+  listOnOtherClient.rebuildFromCore();
+  expect(listOnOtherClient.toJSON()).toEqual(list.toJSON());
+});
+
+test("syncing prepends with an older timestamp", async () => {
+  const client = setupTestNode({
+    connected: true,
+  });
+  const otherClient = setupTestNode({});
+
+  const otherClientConnection = otherClient.connectToSyncServer();
+
+  const coValue = client.node.createCoValue({
+    type: "colist",
+    ruleset: { type: "unsafeAllowAll" },
+    meta: null,
+    ...Crypto.createdNowUnique(),
+  });
+
+  const list = expectList(coValue.getCurrentContent());
+
+  list.prepend(1, undefined, "trusting");
+  list.prepend(2, undefined, "trusting");
+
+  const listOnOtherClient = await loadCoValueOrFail(otherClient.node, list.id);
+
+  otherClientConnection.peerState.gracefulShutdown();
+
+  listOnOtherClient.prepend(3, undefined, "trusting");
+
+  await new Promise((resolve) => setTimeout(resolve, 1));
+
+  list.prepend(4, undefined, "trusting");
+
+  await new Promise((resolve) => setTimeout(resolve, 1));
+
+  listOnOtherClient.prepend(5, undefined, "trusting");
+
+  await new Promise((resolve) => setTimeout(resolve, 1));
+
+  list.prepend(6, undefined, "trusting");
+
+  otherClient.connectToSyncServer();
+
+  await waitFor(() => {
+    list.rebuildFromCore(); // TODO: This is a hack to ensure the list is rebuilt, we can remove it after the incremental processing lands
+    expect(list.toJSON()).toEqual([6, 4, 5, 3, 2, 1]);
+  });
+
+  listOnOtherClient.rebuildFromCore();
   expect(listOnOtherClient.toJSON()).toEqual(list.toJSON());
 });