add tests for embeds in getLastChangeIndex tests

src/SIL.XForge.Scripture/ClientApp/src/app/shared/text/quill-editor-registration/quill-history.spec.ts

@@ -38,6 +38,36 @@ describe('Quill history', () => {
         name: 'retain followed by insert',
         delta: new Delta().retain(3).insert('test'),
         expected: 7
+      },
+      {
+        name: 'single embed insert',
+        delta: new Delta().insert({ image: 'test.jpg' }),
+        expected: 0
+      },
+      {
+        name: 'text followed by embed',
+        delta: new Delta().insert('hello').insert({ image: 'test.jpg' }),
+        expected: 5
+      },
+      {
+        name: 'embed followed by text',
+        delta: new Delta().insert({ image: 'test.jpg' }).insert('hello'),
+        expected: 6
+      },
+      {
+        name: 'mixed text and embeds with trailing text',
+        delta: new Delta().insert({ blank: true }).insert('text').insert({ image: 'test.jpg' }).insert('more'),
+        expected: 10
+      },
+      {
+        name: 'mixed text and embeds with trailing embed',
+        delta: new Delta().insert({ blank: true }).insert('text').insert({ image: 'test.jpg' }),
+        expected: 5
+      },
+      {
+        name: 'retain followed by embed',
+        delta: new Delta().retain(3).insert({ image: 'test.jpg' }),
+        expected: 3
       }
     ];
 

src/SIL.XForge.Scripture/ClientApp/src/app/shared/text/quill-editor-registration/quill-history.ts

@@ -92,7 +92,7 @@ export function removeObsoleteSegmentAttrs(delta: Delta): Delta {
 
 /**
  * Finds the index where the last insert/delete occurs in the delta. This function has been modified from the
- * original in the Quill history module.
+ * original in the Quill history module.  Trailing inserted embeds ops are not counted when determining the last edit.
  *
  * @param {QuillScrollBlot} scroll The Quill scroll.
  * @param {Delta} delta The undo/redo delta.
@@ -102,7 +102,7 @@ export function getLastChangeIndex(scroll: QuillScrollBlot, delta: Delta): numbe
   if (delta.ops == null) {
     return 0;
   }
-  // skip inserted embeds when determining last edit
+  // Skip trailing inserted embed ops when determining last edit
   let changeIndex = 0;
   let curIndex = 0;
   for (const op of delta.ops) {
@@ -111,7 +111,7 @@ export function getLastChangeIndex(scroll: QuillScrollBlot, delta: Delta): numbe
         curIndex += op.insert.length;
         changeIndex = curIndex;
       } else {
-        curIndex++;
+        curIndex++; // Won't be assigned to 'changeIndex' if it is a trailing embed op
       }
     } else if (op.retain != null) {
       const retainCount: number = getRetainCount(op)!;