Fix ytext event.delta - items that are synced and deleted

When items are added and deleted in the same transaction, event.delta would recognize them as added (though they are actually deleted). Now it just ignores them.

src/types/YText.js

@@ -388,7 +388,7 @@ const deleteText = (transaction, left, right, currentAttributes, length) => {
 /**
  * Event that describes the changes on a YText type.
  */
-class YTextEvent extends YEvent {
+export class YTextEvent extends YEvent {
   /**
    * @param {YText} ytext
    * @param {Transaction} transaction
@@ -475,11 +475,13 @@ class YTextEvent extends YEvent {
           switch (item.constructor) {
             case ItemEmbed:
               if (this.adds(item)) {
-                addOp()
+                if (!this.deletes(item)) {
-                action = 'insert'
+                  addOp()
-                // @ts-ignore item is ItemFormat
+                  action = 'insert'
-                insert = item.embed
+                  // @ts-ignore item is ItemFormat
-                addOp()
+                  insert = item.embed
+                  addOp()
+                }
               } else if (this.deletes(item)) {
                 if (action !== 'delete') {
                   addOp()
@@ -496,12 +498,14 @@ class YTextEvent extends YEvent {
               break
             case ItemString:
               if (this.adds(item)) {
-                if (action !== 'insert') {
+                if (!this.deletes(item)) {
-                  addOp()
+                  if (action !== 'insert') {
-                  action = 'insert'
+                    addOp()
+                    action = 'insert'
+                  }
+                  // @ts-ignore
+                  insert += item.string
                 }
-                // @ts-ignore
-                insert += item.string
               } else if (this.deletes(item)) {
                 if (action !== 'delete') {
                   addOp()
@@ -518,23 +522,25 @@ class YTextEvent extends YEvent {
               break
             case ItemFormat:
               if (this.adds(item)) {
-                // @ts-ignore item is ItemFormat
+                if (!this.deletes(item)) {
-                const curVal = currentAttributes.get(item.key) || null
-                // @ts-ignore item is ItemFormat
-                if (curVal !== item.value) {
-                  if (action === 'retain') {
-                    addOp()
-                  }
                   // @ts-ignore item is ItemFormat
-                  if (item.value === (oldAttributes.get(item.key) || null)) {
+                  const curVal = currentAttributes.get(item.key) || null
+                  // @ts-ignore item is ItemFormat
+                  if (curVal !== item.value) {
+                    if (action === 'retain') {
+                      addOp()
+                    }
                     // @ts-ignore item is ItemFormat
-                    delete attributes[item.key]
+                    if (item.value === (oldAttributes.get(item.key) || null)) {
+                      // @ts-ignore item is ItemFormat
+                      delete attributes[item.key]
+                    } else {
+                      // @ts-ignore item is ItemFormat
+                      attributes[item.key] = item.value
+                    }
                   } else {
-                    // @ts-ignore item is ItemFormat
+                    item.delete(transaction)
-                    attributes[item.key] = item.value
                   }
-                } else {
-                  item.delete(transaction)
                 }
               } else if (this.deletes(item)) {
                 // @ts-ignore item is ItemFormat

tests/testHelper.js

@@ -360,7 +360,7 @@ export const compareDS = (ds1, ds2) => {
 /**
  * @template T
  * @param {t.TestCase} tc
- * @param {Array<function(TestYInstance,prng.PRNG,T):void>} mods
+ * @param {Array<function(Y.Doc,prng.PRNG,T):void>} mods
  * @param {number} iterations
  * @param {InitTestObjectCallback<T>} [initTestObject]
  */

tests/y-text.tests.js

@@ -27,6 +27,13 @@ export const testBasicInsertAndDelete = tc => {
   text0.delete(1, 1)
   t.assert(text0.toString() === 'b', 'Basic delete works (position 1)')
   t.compare(delta, [{ retain: 1 }, { delete: 1 }])
+
+  users[0].transact(() => {
+    text0.insert(0, '1')
+    text0.delete(0, 1)
+  })
+  t.compare(delta, [])
+
   compare(users)
 }