Fix insertTextAtRange selection (#2256)

* Make a test case for buggy insertTextAtRange selection behavior

* Insert text at previous path, not selection key, closes #2209

packages/slate/src/commands/at-range.js

@@ -794,7 +794,8 @@ Commands.insertTextAtRange = (change, range, text, marks) => {
   const { document } = value
   const { start } = range
   let key = start.key
-  let offset = start.offset
+  const offset = start.offset
+  const path = start.path
   const parent = document.getParent(start.key)
 
   if (change.isVoid(parent)) {
@@ -805,10 +806,11 @@ Commands.insertTextAtRange = (change, range, text, marks) => {
     if (range.isExpanded) {
       change.deleteAtRange(range)
 
+      const startText = change.value.document.getNode(path)
+
       // Update range start after delete
-      if (change.value.selection.start.key !== key) {
+      if (startText && startText.key !== key) {
-        key = change.value.selection.start.key
+        key = startText.key
-        offset = change.value.selection.start.offset
       }
     }
 

packages/slate/test/changes/at-range/insert-text-at-range/non-matching-section-and-range.js

@@ -0,0 +1,36 @@
+/** @jsx h */
+
+import { Point, Range } from 'slate'
+
+import h from '../../../helpers/h'
+
+export default function(change) {
+  const { key } = change.value.document.getFirstText()
+  const range = new Range({
+    anchor: new Point({ key, offset: 0 }),
+    focus: new Point({ key, offset: 3 }),
+  })
+  change.insertTextAtRange(range, 'That')
+}
+
+export const input = (
+  <value>
+    <document>
+      <line>The change will be here.</line>
+      <line>
+        The cursor is <cursor />over here.
+      </line>
+    </document>
+  </value>
+)
+
+export const output = (
+  <value>
+    <document>
+      <line>That change will be here.</line>
+      <line>
+        The cursor is <cursor />over here.
+      </line>
+    </document>
+  </value>
+)