From e0037a84bd844fdbada55d6ef7dcd562b8ffbf02 Mon Sep 17 00:00:00 2001
From: Jeremy Dormitzer <jeremy.dormitzer@gmail.com>
Date: Sun, 28 Apr 2019 10:58:28 -0400
Subject: [PATCH] Test backreferences and nested nodes

---
 src/JsonLd/JsonLdNode.php      | 36 +++++++++++++++------
 test/JsonLd/JsonLdNodeTest.php | 57 ++++++++++++++++++++++++++++++++--
 2 files changed, 81 insertions(+), 12 deletions(-)

diff --git a/src/JsonLd/JsonLdNode.php b/src/JsonLd/JsonLdNode.php
index f8054f9..ca2b5c8 100644
--- a/src/JsonLd/JsonLdNode.php
+++ b/src/JsonLd/JsonLdNode.php
@@ -173,16 +173,14 @@ class JsonLdNode implements ArrayAccess
             }
             return array_map( array( $this, 'resolveProperty'), $names, $property );
         } else if ( $property instanceof stdClass && property_exists( $property, '@id') ) {
-            // Only dereference if @id is the only property present
-            if ( count( get_object_vars( $property ) ) > 1 ) {
-                return $property;
-            }
-            // Otherwise lazy-load the referenced node
+            // Lazy-load if we only have the @id property
             $idProp = '@id';
-            $iri = $property->$idProp;
-            $dereferenced = $this->dereferencer->dereference( $iri );
-            $expanded = JsonLD::expand( $dereferenced )[0];
-            $property = $expanded;
+            if ( count( get_object_vars( $property ) ) <= 1 ) {
+                $iri = $property->$idProp;
+                $dereferenced = $this->dereferencer->dereference( $iri );
+                $expanded = JsonLD::expand( $dereferenced )[0];
+                $property = $expanded;
+            }
             $referencedNode = $this->graph->getNode( $property->$idProp );
             if ( is_null( $referencedNode) ) {
                 $backrefs = array( $expandedName => array( $this ) );
@@ -315,6 +313,26 @@ class JsonLdNode implements ArrayAccess
         return property_exists( $this->expanded, '@id' );
     }
 
+    /**
+     * Returns the list of nodes which reference this node as the field $name.
+     * @param string $name
+     * @return array
+     */
+    public function getBackReferences( $name )
+    {
+        $expandedName = $this->expandName( $name );
+        if ( array_key_exists( $expandedName, $this->backreferences ) ) {
+            return $this->backreferences[$expandedName];
+        } else {
+            return array();
+        }
+    }
+
+    /**
+     * Adds a new backreference to this node.
+     * @param string $expandedName
+     * @param JsonLdNode $referencingNode
+     */
     public function addBackReference( $expandedName, JsonLdNode $referencingNode )
     {
         $this->backreferences[$expandedName][] = $referencingNode;
diff --git a/test/JsonLd/JsonLdNodeTest.php b/test/JsonLd/JsonLdNodeTest.php
index f2ed4e8..d872904 100644
--- a/test/JsonLd/JsonLdNodeTest.php
+++ b/test/JsonLd/JsonLdNodeTest.php
@@ -400,10 +400,61 @@ class JsonLdNodeTest extends APTestCase
         $this->assertEquals( $expectedValue, $actualValue );
     }
 
-    public function testBackreferences()
+    public function provideForBackreferencesOnGet()
     {
-        // TODO implement me
-        $this->assertTrue( false );
+        return array(
+            array(
+                (object) array(
+                    '@context' => array( 'https://www.w3.org/ns/activitystreams' ),
+                    'id' => 'https://example.org/objects/1',
+                    'type' => 'Note',
+                    'inReplyTo' => (object) array(
+                        'id' => 'https://example.org/articles/1',
+                        'type' => 'Article',
+                    ),
+                ),
+                $this->asContext,
+                'inReplyTo',
+            ),
+        );
+    }
+
+    /**
+     * @dataProvider provideForBackreferencesOnGet
+     */
+    public function testBackreferencesOnGet( $inputObj, $context, $childNodeField, $nodeGraph = array() )
+    {
+        $parentNode = $this->makeJsonLdNode( $inputObj, $context, $nodeGraph );
+        $childNode = $parentNode->$childNodeField;
+        $this->assertInstanceOf( JsonLdNode::class, $childNode );
+        $this->assertEquals( $childNode->getBackReferences( $childNodeField ), array( $parentNode ) );
+    }
+
+    public function provideForBackreferencesOnSet()
+    {
+        return array(
+            array(
+                new stdClass(),
+                $this->asContext,
+                'inReplyTo',
+                (object) array(
+                    'id' => 'https://example.org/articles/1',
+                    'type' => 'Article',
+                )
+            )
+        );
+    }
+
+    /**
+     * @dataProvider provideForBackreferencesOnSet
+     */
+    public function testBackreferencesOnSet( $inputObj, $context, $newPropertyName, $newNodeValue )
+    {
+        $parentNode = $this->makeJsonLdNode( $inputObj, $context );
+        $parentNode->set( $newPropertyName, $newNodeValue );
+        $childNode = $parentNode->get( $newPropertyName );
+        $this->assertInstanceOf( JsonLdNode::class, $childNode );
+        $this->assertEquals( $childNode->getBackReferences( $newPropertyName ), array( $parentNode ) );
     }
 
     private function makeJsonLdNode( $inputObj, $context, $nodeGraph = array() )