13.6.21

Add PSPDFKit binding to README.md

README.md

@@ -120,12 +120,16 @@ Showcase](https://yjs-diagram.synergy.codes/).
 * [Kanbert](https://kanbert.com) - Project management software
 * [Eclipse Theia](https://github.com/eclipse-theia/theia) - A cloud & desktop
   IDE that runs in the browser.
+* [ScienHub](https://scienhub.com) - Collaborative LaTeX editor in the browser.
+* [Open Collaboration Tools](https://www.open-collab.tools/) - Collaborative
+editing for your IDE or custom editor
 
 ## Table of Contents
 
 * [Overview](#overview)
   * [Bindings](#bindings)
   * [Providers](#providers)
+  * [Tooling](#tooling)
   * [Ports](#ports)
 * [Getting Started](#getting-started)
 * [API](#api)
@@ -159,6 +163,7 @@ are implemented in separate modules.
 | React | | [react-yjs](https://github.com/nikgraf/react-yjs) | [demo](https://react-yjs-example.vercel.app/) |
 | React / Vue / Svelte / MobX | | [SyncedStore](https://syncedstore.org) | [demo](https://syncedstore.org/docs/react) |
 | [mobx-keystone](https://mobx-keystone.js.org/) |  | [mobx-keystone-yjs](https://github.com/xaviergonz/mobx-keystone/tree/master/packages/mobx-keystone-yjs) | [demo](https://mobx-keystone.js.org/examples/yjs-binding) |
+| [PSPDFKit](https://www.nutrient.io/) |  | [yjs-pspdfkit](https://github.com/hoangqwe159/yjs-pspdfkit) | [demo](https://github.com/hoangqwe159/yjs-pspdfkit) |
 
 ### Providers
 
@@ -189,7 +194,7 @@ are available. Communication over the signaling servers can be encrypted by
 providing a shared secret, keeping the connection information and the shared
 document private.
   </dd>
-  <dt><a href="https://github.com/liveblocks/liveblocks">@liveblocks/yjs</a></dt>
+  <dt><a href="https://github.com/liveblocks/liveblocks">@liveblocks/yjs </a> 🌟</dt>
   <dd>
 <a href="https://liveblocks.io/document/yjs">Liveblocks Yjs</a> provides a fully
 hosted WebSocket infrastructure and persisted data store for Yjs
@@ -197,15 +202,23 @@ documents. No configuration or maintenance is required. It also features
 Yjs webhook events, REST API to read and update Yjs documents, and a
 browser DevTools extension.
   </dd>
-  <dt><a href="https://github.com/drifting-in-space/y-sweet">y-sweet</a></dt>
+  <dt><a href="https://github.com/drifting-in-space/y-sweet">y-sweet</a> ⭐</dt>
   <dd>
 A standalone yjs server with persistence to S3 or filesystem. They offer a
 <a href="https://y-sweet.cloud">cloud service</a> as well.
   </dd>
-  <dt><a href="https://github.com/ueberdosis/hocuspocus">Hocuspocus</a></dt>
+  <dt><a href="https://github.com/ueberdosis/hocuspocus">Hocuspocus</a> ⭐</dt>
   <dd>
 A standalone extensible yjs server with sqlite persistence, webhooks, auth and more.
   </dd>
+  <dt><a href="https://docs.superviz.com/collaboration/integrations/YJS/overview">@superviz/yjs</a></dt>
+  <dd>
+    SuperViz Yjs Provider comes with a secure, scalable real-time infrastructure
+    for Yjs documents, fully compatible with a set of real-time
+    collaboration components offered by SuperViz. This solution ensures
+    synchronization, offline editing, and real-time updates, enabling
+    multiple users to collaborate effectively within shared workspaces.
+  </dd>
   <dt><a href="https://docs.partykit.io/reference/y-partykit-api/">PartyKit</a></dt>
   <dd>
 Cloud service for building multiplayer apps.
@@ -270,11 +283,6 @@ network provider.
   <dd>
 Adds persistent storage to a server with MongoDB. Can be used with the
 y-websocket provider.
-  </dd>
-  <dt><a href="https://github.com/toeverything/AFFiNE/tree/master/packages/y-indexeddb">
-@toeverything/y-indexeddb</a></dt>
-  <dd>
-Like y-indexeddb, but with sub-documents support and fully TypeScript.
   </dd>
   <dt><a href="https://github.com/podraven/y-fire">y-fire</a></dt>
   <dd>
@@ -293,7 +301,13 @@ A database and connection provider for Yjs based on Firestore.
   </dd>
 </dl>
 
-# Ports
+### Tooling
+
+* [y-sweet debugger](https://docs.jamsocket.com/y-sweet/advanced/debugger)
+* [liveblocks devtools](https://liveblocks.io/devtools)
+* [Yjs inspector](https://inspector.yjs.dev)
+
+### Ports
 
 There are several Yjs-compatible ports to other programming languages.
 
@@ -307,6 +321,7 @@ language bindings to other languages
   * [yswift](https://github.com/y-crdt/yswift) - Swift binding
   * [yffi](https://github.com/y-crdt/y-crdt/tree/main/yffi) - C-FFI
   * [ywasm](https://github.com/y-crdt/y-crdt/tree/main/ywasm) - WASM binding
+  * [y_ex](https://github.com/satoren/y_ex) - Elixir bindings
 * [ycs](https://github.com/yjs/ycs) - .Net compatible C# implementation.
 
 ## Getting Started

funding.json

@@ -0,0 +1,143 @@
+{
+  "version": "v1.0.0",
+  "entity": {
+    "type": "group",
+    "role": "steward",
+    "name": "Kevin Jahns",
+    "email": "kevin.jahns@protonmail.com",
+    "phone": "",
+    "description": "OSS Developer",
+    "webpageUrl": {
+      "url": "https://github.com/yjs"
+    }
+  },
+  "projects": [
+    {
+      "guid": "yjs",
+      "name": "Yjs",
+      "description": "A library for building collaborative applications. #p2p #local-first #CRDT Funding this project will also enable me to maintain the other Yjs-related technologies.",
+      "webpageUrl": {
+        "url": "https://github.com/yjs/yjs"
+      },
+      "repositoryUrl": {
+        "url": "https://github.com/yjs/yjs"
+      },
+      "licenses": [
+        "spdx:MIT"
+      ],
+      "tags": [
+        "collaboration",
+        "p2p",
+        "CRDT",
+        "rich-text",
+        "real-time"
+      ]
+    },
+    {
+      "guid": "ystream",
+      "name": "Y/Stream",
+      "description": "A provider for syncing millions of docs efficiently with other peers. This will become the foundation for building real local-first apps with Yjs.",
+      "webpageUrl": {
+        "url": "https://github.com/yjs/ystream",
+        "wellKnown": "https://github.com/yjs/ystream/blob/main/.well-known/funding-manifest-urls"
+      },
+      "repositoryUrl": {
+        "url": "https://github.com/yjs/ystream",
+        "wellKnown": "https://github.com/yjs/ystream/blob/main/.well-known/funding-manifest-urls"
+      },
+      "licenses": [
+        "spdx:MIT",
+        "spdx:GPL-3.0"
+      ],
+      "tags": [
+        "privacy",
+        "collaboration",
+        "p2p",
+        "CRDT",
+        "rich-text",
+        "real-time",
+        "web-development"
+      ]
+    }
+  ],
+  "funding": {
+    "channels": [
+      {
+        "guid": "github-sponsors",
+        "type": "payment-provider",
+        "address": "",
+        "description": "For funding of the Yjs project"
+      },
+      {
+        "guid": "y-collective",
+        "type": "payment-provider",
+        "address": "https://opencollective.com/y-collective",
+        "description": "For funding the Y-CRDT - the Rust implementation of Yjs and other listed projects."
+      }
+    ],
+    "plans": [
+      {
+        "guid": "supporter",
+        "status": "active",
+        "name": "Supporter",
+        "description": "",
+        "amount": 0,
+        "currency": "USD",
+        "frequency": "monthly",
+        "channels": [
+          "github-sponsors",
+          "y-collective"
+        ]
+      },
+      {
+        "guid": "ystream-funding",
+        "status": "active",
+        "name": "YStream Funding",
+        "description": "Fund the next generation of local-first providers.",
+        "amount": 30000,
+        "currency": "USD",
+        "frequency": "one-time",
+        "channels": [
+          "github-sponsors"
+        ]
+      },
+      {
+        "guid": "bronze-sponsor",
+        "status": "active",
+        "name": "Bronze Sponsor",
+        "description": "This is the recommended plan for companies that use Yjs.",
+        "amount": 500,
+        "currency": "USD",
+        "frequency": "monthly",
+        "channels": [
+          "github-sponsors"
+        ]
+      },
+      {
+        "guid": "silver-sponsor",
+        "status": "active",
+        "name": "Silver Sponsor",
+        "description": "This is the recommended plan for large/successfull companies that use Yjs.",
+        "amount": 1000,
+        "currency": "USD",
+        "frequency": "monthly",
+        "channels": [
+          "github-sponsors"
+        ]
+      },
+      {
+        "guid": "gold-sponsor",
+        "status": "active",
+        "name": "Gold Sponsor",
+        "description": "This is the recommended plan for successful companies that build their entire product around Yjs-related technologies.",
+        "amount": 3000,
+        "currency": "USD",
+        "frequency": "monthly",
+        "channels": [
+          "github-sponsors"
+        ]
+      }
+    ],
+    "history": null
+  }
+}

package-lock.json

@@ -1,15 +1,15 @@
 {
   "name": "yjs",
-  "version": "13.6.19",
+  "version": "13.6.21",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "yjs",
-      "version": "13.6.19",
+      "version": "13.6.21",
       "license": "MIT",
       "dependencies": {
-        "lib0": "^0.2.86"
+        "lib0": "^0.2.98"
       },
       "devDependencies": {
         "@rollup/plugin-commonjs": "^24.0.1",
@@ -2785,13 +2785,14 @@
       }
     },
     "node_modules/lib0": {
-      "version": "0.2.88",
-      "resolved": "https://registry.npmjs.org/lib0/-/lib0-0.2.88.tgz",
-      "integrity": "sha512-KyroiEvCeZcZEMx5Ys+b4u4eEBbA1ch7XUaBhYpwa/nPMrzTjUhI4RfcytmQfYoTBPcdyx+FX6WFNIoNuJzJfQ==",
+      "version": "0.2.98",
+      "resolved": "https://registry.npmjs.org/lib0/-/lib0-0.2.98.tgz",
+      "integrity": "sha512-XteTiNO0qEXqqweWx+b21p/fBnNHUA1NwAtJNJek1oPrewEZs2uiT4gWivHKr9GqCjDPAhchz0UQO8NwU3bBNA==",
       "dependencies": {
         "isomorphic.js": "^0.2.4"
       },
       "bin": {
+        "0ecdsa-generate-keypair": "bin/0ecdsa-generate-keypair.js",
         "0gentesthtml": "bin/gentesthtml.js",
         "0serve": "bin/0serve.js"
       },

package.json

@@ -1,6 +1,6 @@
 {
   "name": "yjs",
-  "version": "13.6.19",
+  "version": "13.6.21",
   "description": "Shared Editing Library",
   "main": "./dist/yjs.cjs",
   "module": "./dist/yjs.mjs",
@@ -13,7 +13,7 @@
   },
   "scripts": {
     "clean": "rm -rf dist docs",
-    "test": "npm run dist && node ./dist/tests.cjs --repetition-time 50",
+    "test": "npm run dist && NODE_ENV=development node ./dist/tests.cjs --repetition-time 50",
     "test-extensive": "npm run lint && npm run dist && node ./dist/tests.cjs --production --repetition-time 10000",
     "dist": "npm run clean && rollup -c && tsc",
     "watch": "rollup -wc",
@@ -76,7 +76,7 @@
   },
   "homepage": "https://docs.yjs.dev",
   "dependencies": {
-    "lib0": "^0.2.86"
+    "lib0": "^0.2.98"
   },
   "devDependencies": {
     "@rollup/plugin-commonjs": "^24.0.1",

src/structs/ContentAny.js

@@ -2,6 +2,11 @@ import {
   UpdateEncoderV1, UpdateEncoderV2, UpdateDecoderV1, UpdateDecoderV2, Transaction, Item, StructStore // eslint-disable-line
 } from '../internals.js'
 
+import * as env from 'lib0/environment'
+import * as object from 'lib0/object'
+
+const isDevMode = env.getVariable('node_env') === 'development'
+
 export class ContentAny {
   /**
    * @param {Array<any>} arr
@@ -11,6 +16,7 @@ export class ContentAny {
      * @type {Array<any>}
      */
     this.arr = arr
+    isDevMode && object.deepFreeze(arr)
   }
 
   /**

src/types/AbstractType.js

@@ -17,6 +17,12 @@ import * as map from 'lib0/map'
 import * as iterator from 'lib0/iterator'
 import * as error from 'lib0/error'
 import * as math from 'lib0/math'
+import * as log from 'lib0/logging'
+
+/**
+ * https://docs.yjs.dev/getting-started/working-with-shared-types#caveats
+ */
+export const warnPrematureAccess = () => { log.warn('Invalid access: Add Yjs type to a document before reading data.') }
 
 const maxSearchMarker = 80
 
@@ -215,6 +221,7 @@ export const updateMarkerChanges = (searchMarker, index, len) => {
  * @return {Array<Item>}
  */
 export const getTypeChildren = t => {
+  t.doc ?? warnPrematureAccess()
   let s = t._start
   const arr = []
   while (s) {
@@ -408,6 +415,7 @@ export class AbstractType {
  * @function
  */
 export const typeListSlice = (type, start, end) => {
+  type.doc ?? warnPrematureAccess()
   if (start < 0) {
     start = type._length + start
   }
@@ -443,6 +451,7 @@ export const typeListSlice = (type, start, end) => {
  * @function
  */
 export const typeListToArray = type => {
+  type.doc ?? warnPrematureAccess()
   const cs = []
   let n = type._start
   while (n !== null) {
@@ -492,6 +501,7 @@ export const typeListToArraySnapshot = (type, snapshot) => {
 export const typeListForEach = (type, f) => {
   let index = 0
   let n = type._start
+  type.doc ?? warnPrematureAccess()
   while (n !== null) {
     if (n.countable && !n.deleted) {
       const c = n.content.getContent()
@@ -606,6 +616,7 @@ export const typeListForEachSnapshot = (type, f, snapshot) => {
  * @function
  */
 export const typeListGet = (type, index) => {
+  type.doc ?? warnPrematureAccess()
   const marker = findMarker(type, index)
   let n = type._start
   if (marker !== null) {
@@ -874,6 +885,7 @@ export const typeMapSet = (transaction, parent, key, value) => {
  * @function
  */
 export const typeMapGet = (parent, key) => {
+  parent.doc ?? warnPrematureAccess()
   const val = parent._map.get(key)
   return val !== undefined && !val.deleted ? val.content.getContent()[val.length - 1] : undefined
 }
@@ -890,6 +902,7 @@ export const typeMapGetAll = (parent) => {
    * @type {Object<string,any>}
    */
   const res = {}
+  parent.doc ?? warnPrematureAccess()
   parent._map.forEach((value, key) => {
     if (!value.deleted) {
       res[key] = value.content.getContent()[value.length - 1]
@@ -907,6 +920,7 @@ export const typeMapGetAll = (parent) => {
  * @function
  */
 export const typeMapHas = (parent, key) => {
+  parent.doc ?? warnPrematureAccess()
   const val = parent._map.get(key)
   return val !== undefined && !val.deleted
 }
@@ -957,10 +971,13 @@ export const typeMapGetAllSnapshot = (parent, snapshot) => {
 }
 
 /**
- * @param {Map<string,Item>} map
+ * @param {AbstractType<any> & { _map: Map<string, Item> }} type
  * @return {IterableIterator<Array<any>>}
  *
  * @private
  * @function
  */
-export const createMapIterator = map => iterator.iteratorFilter(map.entries(), /** @param {any} entry */ entry => !entry[1].deleted)
+export const createMapIterator = type => {
+  type.doc ?? warnPrematureAccess()
+  return iterator.iteratorFilter(type._map.entries(), /** @param {any} entry */ entry => !entry[1].deleted)
+}

src/types/YArray.js

@@ -16,6 +16,7 @@ import {
   YArrayRefID,
   callTypeObservers,
   transact,
+  warnPrematureAccess,
   ArraySearchMarker, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'
 import { typeListSlice } from './AbstractType.js'
@@ -104,7 +105,8 @@ export class YArray extends AbstractType {
   }
 
   get length () {
-    return this._prelimContent === null ? this._length : this._prelimContent.length
+    this.doc ?? warnPrematureAccess()
+    return this._length
   }
 
   /**

src/types/YMap.js

@@ -13,6 +13,7 @@ import {
   YMapRefID,
   callTypeObservers,
   transact,
+  warnPrematureAccess,
   UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'
 
@@ -121,6 +122,7 @@ export class YMap extends AbstractType {
    * @return {Object<string,any>}
    */
   toJSON () {
+    this.doc ?? warnPrematureAccess()
     /**
      * @type {Object<string,MapType>}
      */
@@ -140,7 +142,7 @@ export class YMap extends AbstractType {
    * @return {number}
    */
   get size () {
-    return [...createMapIterator(this._map)].length
+    return [...createMapIterator(this)].length
   }
 
   /**
@@ -149,7 +151,7 @@ export class YMap extends AbstractType {
    * @return {IterableIterator<string>}
    */
   keys () {
-    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[0])
+    return iterator.iteratorMap(createMapIterator(this), /** @param {any} v */ v => v[0])
   }
 
   /**
@@ -158,7 +160,7 @@ export class YMap extends AbstractType {
    * @return {IterableIterator<MapType>}
    */
   values () {
-    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[1].content.getContent()[v[1].length - 1])
+    return iterator.iteratorMap(createMapIterator(this), /** @param {any} v */ v => v[1].content.getContent()[v[1].length - 1])
   }
 
   /**
@@ -167,7 +169,7 @@ export class YMap extends AbstractType {
    * @return {IterableIterator<[string, MapType]>}
    */
   entries () {
-    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => /** @type {any} */ ([v[0], v[1].content.getContent()[v[1].length - 1]]))
+    return iterator.iteratorMap(createMapIterator(this), /** @param {any} v */ v => /** @type {any} */ ([v[0], v[1].content.getContent()[v[1].length - 1]]))
   }
 
   /**
@@ -176,6 +178,7 @@ export class YMap extends AbstractType {
    * @param {function(MapType,string,YMap<MapType>):void} f A function to execute on every element of this YArray.
    */
   forEach (f) {
+    this.doc ?? warnPrematureAccess()
     this._map.forEach((item, key) => {
       if (!item.deleted) {
         f(item.content.getContent()[item.length - 1], key, this)

src/types/YText.js

@@ -26,6 +26,7 @@ import {
   typeMapGetAll,
   updateMarkerChanges,
   ContentType,
+  warnPrematureAccess,
   ArraySearchMarker, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, ID, Doc, Item, Snapshot, Transaction // eslint-disable-line
 } from '../internals.js'
 
@@ -875,6 +876,7 @@ export class YText extends AbstractType {
    * @type {number}
    */
   get length () {
+    this.doc ?? warnPrematureAccess()
     return this._length
   }
 
@@ -931,6 +933,7 @@ export class YText extends AbstractType {
    * @public
    */
   toString () {
+    this.doc ?? warnPrematureAccess()
     let str = ''
     /**
      * @type {Item|null}
@@ -1004,6 +1007,7 @@ export class YText extends AbstractType {
    * @public
    */
   toDelta (snapshot, prevSnapshot, computeYChange) {
+    this.doc ?? warnPrematureAccess()
     /**
      * @type{Array<any>}
      */

src/types/YXmlFragment.js

@@ -17,6 +17,7 @@ import {
   transact,
   typeListGet,
   typeListSlice,
+  warnPrematureAccess,
   UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, ContentType, Transaction, Item, YXmlText, YXmlHook // eslint-disable-line
 } from '../internals.js'
 
@@ -66,6 +67,7 @@ export class YXmlTreeWalker {
      */
     this._currentNode = /** @type {Item} */ (root._start)
     this._firstCall = true
+    root.doc ?? warnPrematureAccess()
   }
 
   [Symbol.iterator] () {
@@ -177,6 +179,7 @@ export class YXmlFragment extends AbstractType {
   }
 
   get length () {
+    this.doc ?? warnPrematureAccess()
     return this._prelimContent === null ? this._length : this._prelimContent.length
   }
 

src/utils/RelativePosition.js

@@ -9,7 +9,7 @@ import {
   ContentType,
   followRedone,
   getItem,
-  ID, Doc, AbstractType // eslint-disable-line
+  StructStore, ID, Doc, AbstractType, // eslint-disable-line
 } from '../internals.js'
 
 import * as encoding from 'lib0/encoding'
@@ -256,6 +256,18 @@ export const readRelativePosition = decoder => {
  */
 export const decodeRelativePosition = uint8Array => readRelativePosition(decoding.createDecoder(uint8Array))
 
+/**
+ * @param {StructStore} store
+ * @param {ID} id
+ */
+const getItemWithOffset = (store, id) => {
+  const item = getItem(store, id)
+  const diff = id.clock - item.id.clock
+  return {
+    item, diff
+  }
+}
+
 /**
  * Transform a relative position to an absolute position.
  *
@@ -286,7 +298,7 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc, followUndo
     if (getState(store, rightID.client) <= rightID.clock) {
       return null
     }
-    const res = followUndoneDeletions ? followRedone(store, rightID) : { item: getItem(store, rightID), diff: 0 }
+    const res = followUndoneDeletions ? followRedone(store, rightID) : getItemWithOffset(store, rightID)
     const right = res.item
     if (!(right instanceof Item)) {
       return null

tests/index.js

@@ -15,15 +15,28 @@ import * as relativePositions from './relativePositions.tests.js'
 import { runTests } from 'lib0/testing'
 import { isBrowser, isNode } from 'lib0/environment'
 import * as log from 'lib0/logging'
+import { environment } from 'lib0'
 
 if (isBrowser) {
   log.createVConsole(document.body)
 }
-runTests({
+
+/**
+ * @type {any}
+ */
+const tests = {
   doc, map, array, text, xml, encoding, undoredo, compatibility, snapshot, updates, relativePositions
-}).then(success => {
+}
+
+const run = async () => {
+  if (environment.isNode) {
+    // tests.nodejs = await import('./node.tests.js')
+  }
+
+  const success = await runTests(tests)
   /* istanbul ignore next */
   if (isNode) {
     process.exit(success ? 0 : 1)
   }
-})
+}
+run()

tests/relativePositions.tests.js

@@ -85,6 +85,26 @@ export const testRelativePositionCase6 = tc => {
   checkRelativePositions(ytext)
 }
 
+/**
+ * Testing https://github.com/yjs/yjs/issues/657
+ *
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase7 = tc => {
+  const docA = new Y.Doc()
+  const textA = docA.getText('text')
+  textA.insert(0, 'abcde')
+  // Create a relative position at index 2 in 'textA'
+  const relativePosition = Y.createRelativePositionFromTypeIndex(textA, 2)
+  // Verify that the absolutes positions on 'docA' are the same
+  const absolutePositionWithFollow =
+    Y.createAbsolutePositionFromRelativePosition(relativePosition, docA, true)
+  const absolutePositionWithoutFollow =
+    Y.createAbsolutePositionFromRelativePosition(relativePosition, docA, false)
+  t.assert(absolutePositionWithFollow?.index === 2)
+  t.assert(absolutePositionWithoutFollow?.index === 2)
+}
+
 /**
  * @param {t.TestCase} tc
  */

tests/y-array.tests.js

@@ -4,6 +4,9 @@ import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'
 import * as prng from 'lib0/prng'
 import * as math from 'lib0/math'
+import * as env from 'lib0/environment'
+
+const isDevMode = env.getVariable('node_env') === 'development'
 
 /**
  * @param {t.TestCase} tc
@@ -17,6 +20,28 @@ export const testBasicUpdate = tc => {
   t.compare(doc2.getArray('array').toArray(), ['hi'])
 }
 
+/**
+ * @param {t.TestCase} tc
+ */
+export const testFailsObjectManipulationInDevMode = tc => {
+  if (isDevMode) {
+    t.info('running in dev mode')
+    const doc = new Y.Doc()
+    const a = [1, 2, 3]
+    const b = { o: 1 }
+    doc.getArray('test').insert(0, [a])
+    doc.getMap('map').set('k', b)
+    t.fails(() => {
+      a[0] = 42
+    })
+    t.fails(() => {
+      b.o = 42
+    })
+  } else {
+    t.info('not in dev mode')
+  }
+}
+
 /**
  * @param {t.TestCase} tc
  */