Fix skip this in getFurtherstLonelyAncestor (#1628)

* Fix skip this in getFurtherstLonelyAncestor

* export runTest in models/

* Change the path of test getOnlyChildAncestor

* Update index.js

* Update get-furthest-only-child.js

* Fix for linting

packages/slate/src/models/node.js

@@ -845,16 +845,16 @@ class Node {
       throw new Error(`Could not find a descendant node with key "${key}".`)
     }
 
-    return (
-      ancestors
-        // Skip this node...
-        .skipLast()
-        // Take parents until there are more than one child...
-        .reverse()
-        .takeUntil(p => p.nodes.size > 1)
-        // And pick the highest.
-        .last()
-    )
+    const result = ancestors
+      // Skip this node...
+      .shift()
+      // Take parents until there are more than one child...
+      .reverse()
+      .takeUntil(p => p.nodes.size > 1)
+      // And pick the highest.
+      .last()
+    if (!result) return null
+    return result
   }
 
   /**

packages/slate/test/models/index.js

@@ -33,4 +33,21 @@ describe('models', () => {
       }
     })
   })
+
+  describe('node', () => {
+    describe('node', () => {
+      const testsDir = resolve(__dirname, 'node')
+      const tests = fs
+        .readdirSync(testsDir)
+        .filter(t => t[0] != '.')
+        .map(t => basename(t, extname(t)))
+
+      for (const test of tests) {
+        it(test, async () => {
+          const run = require(resolve(testsDir, test)).default
+          run()
+        })
+      }
+    })
+  })
 })

packages/slate/test/models/node/get-furthest-only-child.js

@@ -0,0 +1,21 @@
+/** @jsx h */
+
+import h from '../../helpers/h'
+import assert from 'assert'
+
+export default function() {
+  const { document } = (
+    <value>
+      <document>
+        <paragraph>Some Text</paragraph>
+      </document>
+    </value>
+  )
+
+  const paragraph = document.nodes.first()
+  const text = paragraph.getFirstText()
+
+  assert.equal(document.getFurthestOnlyChildAncestor(paragraph.key), null)
+  assert.equal(paragraph.getFurthestOnlyChildAncestor(text.key), null)
+  assert.equal(document.getFurthestOnlyChildAncestor(text.key), paragraph)
+}