Fix replaceChild functionality

Author: alcaeus

src/PHPHtmlParser/Dom/InnerNode.php

@@ -235,13 +235,25 @@ public function isChild($id)
      */
     public function replaceChild($childId, AbstractNode $newChild)
     {
-        $oldChild                        = $this->getChild($childId);
-        $keys                            = array_keys($this->children);
-        $index                           = array_search($childId, $keys, true);
-        $keys[$index]                    = $newChild->id();
-        $this->children                  = array_combine($keys, $this->children);
-        $this->children[$newChild->id()] = $newChild;
-        unset($oldChild);
+        // Replace key of old child
+        $keys           = array_keys($this->children);
+        $index          = array_search($childId, $keys, true);
+        $keys[$index]   = $newChild->id();
+        $this->children = array_combine($keys, $this->children);
+
+        // Replace old child node with new one
+        $this->children[$newChild->id()]['node'] = $newChild;
+
+        $child = $this->children[$newChild->id()];
+
+        // Update previous and next nodes
+        if ($child['prev'] !== null) {
+            $this->children[$child['prev']]['next'] = $newChild->id();
+        }
+
+        if ($child['next'] !== null) {
+            $this->children[$child['next']]['prev'] = $newChild->id();
+        }
     }
 
     /**
@@ -314,4 +326,4 @@ public function setParent(InnerNode $parent)
 
         return parent::setParent($parent);
     }
-}
+}

tests/Node/ParentTest.php

@@ -142,14 +142,62 @@ public function testLastChild()
     public function testReplaceChild()
     {
         $parent = new Node;
-        $child  = new Node;
+        $child1 = new Node;
         $child2 = new Node;
         $child3 = new Node;
-        $parent->addChild($child);
+        $child4 = new Node;
+        $parent->addChild($child1);
         $parent->addChild($child2);
-        $parent->replaceChild($child->id(), $child3);
+        $parent->addChild($child3);
 
-        $this->assertFalse($parent->isChild($child->id()));
+        self::assertAttributeEquals(
+            [
+                $child1->id() => [
+                    'next' => $child2->id(),
+                    'prev' => null,
+                    'node' => $child1,
+                ],
+                $child2->id() => [
+                    'next' => $child3->id(),
+                    'prev' => $child1->id(),
+                    'node' => $child2,
+                ],
+                $child3->id() => [
+                    'next' => null,
+                    'prev' => $child2->id(),
+                    'node' => $child3,
+                ],
+            ],
+            'children',
+            $parent
+        );
+
+        $parent->replaceChild($child2->id(), $child4);
+
+        $this->assertFalse($parent->isChild($child2->id()));
+        $this->assertTrue($parent->isChild($child4->id()));
+
+        self::assertAttributeEquals(
+            [
+                $child1->id() => [
+                    'next' => $child4->id(),
+                    'prev' => null,
+                    'node' => $child1,
+                ],
+                $child3->id() => [
+                    'next' => null,
+                    'prev' => $child4->id(),
+                    'node' => $child3,
+                ],
+                $child4->id() => [
+                    'next' => $child3->id(),
+                    'prev' => $child1->id(),
+                    'node' => $child4,
+                ],
+            ],
+            'children',
+            $parent
+        );
     }
 
     public function testSetParentDescendantException()