Fix reverting full references if label exists

Closes GH-22.
Related to GH-20.
Related to syntax-tree/mdast#23.
Related to remarkjs/remark#346.

Co-authored-by: Sam Ruby <[email protected]>

Author: wooorm

lib/revert.js

@@ -16,7 +16,7 @@ function revert(h, node) {
   if (subtype === 'collapsed') {
     suffix += '[]'
   } else if (subtype === 'full') {
-    suffix += '[' + node.identifier + ']'
+    suffix += '[' + (node.label || node.identifier) + ']'
   }
 
   if (node.type === 'imageReference') {

test/image-reference.js

@@ -66,5 +66,18 @@ test('ImageReference', function(t) {
     'should transform `imageReference`s to `img`s'
   )
 
+  t.deepEqual(
+    to(
+      u('imageReference', {
+        identifier: 'tango',
+        label: 'Tango',
+        referenceType: 'full',
+        alt: 'uniform'
+      })
+    ),
+    u('text', '![uniform][Tango]'),
+    'should fall back on the label on a full `imageReference` (GH-22)'
+  )
+
   t.end()
 })

test/link-reference.js

@@ -69,5 +69,18 @@ test('LinkReference', function(t) {
     'should transform `linkReference`s to `a`s'
   )
 
+  t.deepEqual(
+    to(
+      u('linkReference', {
+        identifier: 'oscar',
+        label: 'Oscar',
+        referenceType: 'full',
+        alt: 'papa'
+      })
+    ),
+    u('text', '![papa][Oscar]'),
+    'should fall back on the label on a full `linkReference` (GH-22)'
+  )
+
   t.end()
 })