Fixed regression in #4208 where normalization on empty block nodes co…

…uld not be overridden (#4431)

.changeset/popular-ways-fail.md

@@ -0,0 +1,5 @@
+---
+'slate': minor
+---
+
+Fixed regression in #4208 where normalization on empty block nodes could not be overridden

packages/slate/src/interfaces/editor.ts

@@ -997,16 +997,18 @@ export const Editor: EditorInterface = {
       */
       for (const dirtyPath of getDirtyPaths(editor)) {
         if (Node.has(editor, dirtyPath)) {
-          const [node, _] = Editor.node(editor, dirtyPath)
+          const entry = Editor.node(editor, dirtyPath)
+          const [node, _] = entry
+
+          /*
+            The default normalizer inserts an empty text node in this scenario, but it can be customised.
+            So there is some risk here.
 
-          // Add a text child to elements with no children.
-          // This is safe to do in any order, by definition it can't cause other paths to change.
+            As long as the normalizer only inserts child nodes for this case it is safe to do in any order;
+            by definition adding children to an empty node can't cause other paths to change.
+          */
           if (Element.isElement(node) && node.children.length === 0) {
-            const child = { text: '' }
-            Transforms.insertNodes(editor, child, {
-              at: dirtyPath.concat(0),
-              voids: true,
-            })
+            editor.normalizeNode(entry)
           }
         }
       }

packages/slate/test/normalization/block/insert-custom-block.tsx

@@ -0,0 +1,40 @@
+/** @jsx jsx */
+import { jsx } from '../..'
+import { Editor, Element, Transforms } from 'slate'
+
+export const input = (
+  <editor>
+    <element type="body" />
+  </editor>
+)
+
+// patch in a custom normalizer that inserts empty paragraphs in the body instead of text nodes
+// this test also verifies the new node itself is also normalized, because it's inserting a non-normalized node
+const editor = (input as unknown) as Editor
+const defaultNormalize = editor.normalizeNode
+editor.normalizeNode = entry => {
+  const [node, path] = entry
+  if (
+    Element.isElement(node) &&
+    node.children.length === 0 &&
+    (node as any).type === 'body'
+  ) {
+    const child = { type: 'paragraph', children: [] }
+    Transforms.insertNodes(editor, child, {
+      at: path.concat(0),
+      voids: true,
+    })
+  } else {
+    defaultNormalize(entry)
+  }
+}
+
+export const output = (
+  <editor>
+    <element type="body">
+      <element type="paragraph">
+        <text />
+      </element>
+    </element>
+  </editor>
+)