Fix test case

Author: itosho

src/Model/Behavior/InsertBehavior.php

@@ -57,7 +57,7 @@ public function bulkInsert(array $entities)
     }
 
     /**
-     * execute insert select query for saving a record at once
+     * execute insert select query for saving a record just once
      *
      * @param Entity $entity insert entity
      * @param array|null $conditions search conditions
@@ -67,6 +67,12 @@ public function insertOnce(Entity $entity, array $conditions = null)
     {
         if ($this->_config['event']['beforeSave']) {
             $this->_table->dispatchEvent('Model.beforeSave', compact('entity'));
+            if ($entity->created) {
+                $entity->created= $entity->created->toDateString();
+            }
+            if ($entity->modified) {
+                $entity->modified= $entity->modified->toDateString();
+            }
         }
 
         $entity->setVirtual([]);

tests/TestCase/Model/Behavior/InsertBehaviorTest.php

@@ -240,7 +240,11 @@ public function testInsertOnceWhenIsNull()
 
         $actual = $this->Articles
             ->find()
-            ->where($newData)
+            ->where( [
+                'title' => 'First Article',
+                'body IS' => null,
+                'published' => 1
+            ])
             ->all();
 
         $this->assertCount(1, $actual, 'fail insert once.');