avoid warning when saveAll() data has empty hasMany data, fixes #2792

lib/Cake/Model/Model.php

@@ -2036,6 +2036,9 @@ class Model extends Object implements CakeEventListener {
 
 		if (empty($data) && $options['validate'] !== false) {
 			$result = $this->save($data, $options);
+			if (!$options['atomic']) {
+				return array(!empty($result));
+			}
 			return !empty($result);
 		}
 
@@ -2167,6 +2170,9 @@ class Model extends Object implements CakeEventListener {
 
 		if (empty($data) && $options['validate'] !== false) {
 			$result = $this->save($data, $options);
+			if (!$options['atomic']) {
+				return array(!empty($result));
+			}
 			return !empty($result);
 		}
 

lib/Cake/Test/Case/Model/ModelWriteTest.php

@@ -5228,6 +5228,22 @@ class ModelWriteTest extends BaseModelTest {
 		$this->assertEquals($expected, Set::extract($result['Comment'], '{n}.comment'));
 	}
 
+/**
+ * testSaveAssociatedHasManyEmpty method
+ *
+ * @return void
+ */
+	public function testSaveAssociatedHasManyEmpty() {
+		$this->loadFixtures('Article', 'Comment');
+		$TestModel = new Article();
+		$TestModel->belongsTo = $TestModel->hasAndBelongsToMany = array();
+		$result = $TestModel->saveAssociated(array(
+			'Article' => array('title' => 'title', 'author_id' => 1),
+			'Comment' => array()
+		), array('validate' => true));
+		$this->assertTrue($result);
+	}
+
 /**
  * testSaveAssociatedHasManyValidation method
  *