Improve serialization

src/config/normalize/lib/wild_wild_path/parsing/serialize.js

@@ -1,4 +1,4 @@
-import { TOKEN_SEPARATOR } from '../tokens/escape.js'
+import { TOKEN_SEPARATOR, PATH_SEPARATOR } from '../tokens/escape.js'
 import { getObjectTokenType } from '../tokens/main.js'
 
 import { parse } from './parse.js'
@@ -7,8 +7,18 @@ import { parse } from './parse.js'
 // When passing a query string, it is parsed and re-serialized to validate and
 // normalize it.
 export const serialize = function (queryOrPath) {
-  const path = parse(queryOrPath)
-  return path.map(serializeToken).join(TOKEN_SEPARATOR)
+  const paths = parse(queryOrPath)
+  return paths.map(serializePath).join(PATH_SEPARATOR)
+}
+
+const serializePath = function (path) {
+  return path.every(isEmptyToken)
+    ? TOKEN_SEPARATOR.repeat(path.length + 1)
+    : path.map(serializeToken).join(TOKEN_SEPARATOR)
+}
+
+const isEmptyToken = function (token) {
+  return token === ''
 }
 
 const serializeToken = function (token, index) {