Issue #4: replacing document root with add() fixed

Author: remorhaz

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Fixed
+- Issue #3: replacing document root with `add()` fixed.
+
 ## [0.6.2] - 2019-11-18
 ### Fixed
 - Issue #3: adding element to empty array fixed.

src/Processor/Processor.php

@@ -139,7 +139,12 @@ public function add(QueryInterface $query, NodeValueInterface $rootNode, NodeVal
 
     private function createAddMutation(QueryResultInterface $queryResult, NodeValueInterface $value): ?MutationInterface
     {
-        if (!$queryResult->hasParent() || !$queryResult->hasLastReference()) {
+        if (!$queryResult->hasParent()) {
+            return $queryResult->hasSelection()
+                ? new ReplaceMutation($value, $queryResult->getSelection()->getPath())
+                : null;
+        }
+        if (!$queryResult->hasLastReference()) {
             return null;
         }
         $parent = $queryResult->getParent();

tests/AcceptanceTest.php

@@ -108,6 +108,11 @@ public function providerAdd(): array
         return [
             'Add element to empty array' => ['[]', '/0', '1', '[1]'],
             'Add property to empty object' => ['{}', '/a', '"b"', '{"a":"b"}'],
+            'Replace root array with object' => ['[1]', '', '{"a":"b"}', '{"a":"b"}'],
+            'Replace root scalar' => ['1', '', '"a"', '"a"'],
+            'Insert array element' => ['[1,2]', '/1', '3', '[1,3,2]'],
+            'Append array element by index' => ['[1,2]', '/2', '3', '[1,2,3]'],
+            'Auto-append array element' => ['[1,2]', '/-', '3', '[1,2,3]'],
         ];
     }
 }