Fix reporting of marks on a markableVoid (#5186)

Add a few unit tests for Editor.marks(), including one for markable void
that fails

.changeset/sixty-ghosts-invent.md

@@ -0,0 +1,5 @@
+---
+'slate': patch
+---
+
+Report marks applied to a markableVoid if selection is collapsed

packages/slate/src/interfaces/editor.ts

@@ -816,6 +816,10 @@ export const Editor: EditorInterface = {
 
     if (anchor.offset === 0) {
       const prev = Editor.previous(editor, { at: path, match: Text.isText })
+      const markedVoid = Editor.above(editor, {
+        match: n => Editor.isVoid(editor, n) && editor.markableVoid(n),
+      })
+      if (!markedVoid) {
         const block = Editor.above(editor, {
           match: n => Editor.isBlock(editor, n),
         })
@@ -829,6 +833,7 @@ export const Editor: EditorInterface = {
           }
         }
       }
+    }
 
     const { text, ...rest } = node
     return rest

packages/slate/test/interfaces/Editor/marks/markable-void-collapsed.tsx

@@ -0,0 +1,21 @@
+/** @jsx jsx */
+import { Editor } from 'slate'
+import { jsx } from '../../..'
+
+export const input = (
+  <editor>
+    <block>
+      <text>word</text>
+      <inline void markable>
+        <text bold />
+        <cursor />
+      </inline>
+      <text />
+    </block>
+  </editor>
+)
+export const test = editor => {
+  editor.markableVoid = node => node.markable
+  return Editor.marks(editor)
+}
+export const output = { bold: true }

packages/slate/test/interfaces/Editor/marks/markable-voids-mixed.tsx

@@ -0,0 +1,32 @@
+/** @jsx jsx */
+import { Editor } from 'slate'
+import { jsx } from '../../..'
+
+export const input = (
+  <editor>
+    <block>
+      <text>word</text>
+      <inline void markable>
+        <anchor />
+        <text bold />
+      </inline>
+      <text bold>
+        <anchor />
+        bold
+      </text>
+      <inline void markable>
+        <text bold italic />
+      </inline>
+      <text bold italic>
+        bold italic
+        <focus />
+      </text>
+      <text />
+    </block>
+  </editor>
+)
+export const test = editor => {
+  editor.markableVoid = node => node.markable
+  return Editor.marks(editor)
+}
+export const output = { bold: true }

packages/slate/test/interfaces/Editor/marks/mixed-text.tsx

@@ -0,0 +1,24 @@
+/** @jsx jsx */
+import { Editor } from 'slate'
+import { jsx } from '../../..'
+
+export const input = (
+  <editor>
+    <block>
+      plain
+      <text bold>
+        <anchor />
+        bold
+      </text>
+      <text bold italic>
+        bold italic
+        <focus />
+      </text>
+    </block>
+    <block>block two</block>
+  </editor>
+)
+export const test = editor => {
+  return Editor.marks(editor)
+}
+export const output = { bold: true }

packages/slate/test/interfaces/Editor/marks/text-collapsed.tsx

@@ -0,0 +1,24 @@
+/** @jsx jsx */
+import { Editor } from 'slate'
+import { jsx } from '../../..'
+
+export const input = (
+  <editor>
+    <block>
+      plain
+      <text bold>
+        text that is
+        <cursor />
+        bold
+      </text>
+      <text bold italic>
+        bold italic
+      </text>
+    </block>
+    <block>block two</block>
+  </editor>
+)
+export const test = editor => {
+  return Editor.marks(editor)
+}
+export const output = { bold: true }