Assigning null to parent_id attribute now sets the node as root as we…

…ll (performing the same behaviour as 'makeRoot()'). Fixes etrepat#54.

src/Baum/Node.php

@@ -929,9 +929,7 @@ public function setDefaultLeftAndRight() {
    * @return void
    */
   public function storeNewParent() {
-    $dirty = $this->getDirty();
-
-    if ( isset($dirty[$this->getParentColumnName()]) )
+    if ( $this->isDirty($this->getParentColumnName()) )
       static::$moveToNewParentId = $this->getParentId();
     else
       static::$moveToNewParentId = FALSE;

tests/BaumTest.php

@@ -644,6 +644,23 @@ public function testMakeRoot() {
     $this->assertTrue(Category::isValid());
   }
 
+  public function testNullifyParentColumnMakesItRoot() {
+    $node = $this->categories('Child 2');
+
+    $node->parent_id = null;
+
+    $node->save();
+
+    $this->assertNull($node->parent()->first());
+    $this->assertEquals(0, $node->getLevel());
+    $this->assertEquals(7, $node->getLeft());
+    $this->assertEquals(10, $node->getRight());
+
+    $this->assertEquals(1, $this->categories('Child 2.1')->getLevel());
+
+    $this->assertTrue(Category::isValid());
+  }
+
   public function testMakeChildOf() {
     $this->categories('Child 1')->makeChildOf($this->categories('Child 3'));