Add failing test for undo of joinNode

test/transforms/fixtures/on-history/undo/join-node-block/index.js

@@ -0,0 +1,18 @@
+
+import assert from 'assert'
+
+export default function (state) {
+  const { selection } = state
+
+  const next = state
+    .transform()
+    .joinNodeByKey('key2', 'key1')
+    .apply()
+
+    .transform()
+    .undo()
+    .apply()
+
+  assert.deepEqual(next.selection.toJS(), selection.toJS())
+  return next
+}

test/transforms/fixtures/on-history/undo/join-node-block/input.yaml

@@ -0,0 +1,14 @@
+
+nodes:
+  - kind: block
+    key: 'key1'
+    type: paragraph
+    nodes:
+      - kind: text
+        text: The
+  - kind: block
+    key: 'key2'
+    type: paragraph
+    nodes:
+      - kind: text
+        text: text

test/transforms/fixtures/on-history/undo/join-node-block/output.yaml

@@ -0,0 +1,14 @@
+
+nodes:
+  - kind: block
+    key: 'key1'
+    type: paragraph
+    nodes:
+      - kind: text
+        text: The
+  - kind: block
+    key: 'key2'
+    type: paragraph
+    nodes:
+      - kind: text
+        text: text