test and docs to be clear about #4558

framework/base/Model.php

@@ -385,7 +385,6 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
         if ($this->_validators === null) {
             $this->_validators = $this->createValidators();
         }
-
         return $this->_validators;
     }
 
@@ -404,7 +403,6 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
                 $validators[] = $validator;
             }
         }
-
         return $validators;
     }
 
@@ -427,7 +425,6 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
                 throw new InvalidConfigException('Invalid validation rule: a rule must specify both attribute names and validator type.');
             }
         }
-
         return $validators;
     }
 
@@ -436,6 +433,12 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
      * This is determined by checking if the attribute is associated with a
      * [[\yii\validators\RequiredValidator|required]] validation rule in the
      * current [[scenario]].
+     *
+     * Note that when the validator has a conditional validation applied using
+     * [[\yii\validators\RequiredValidator::$when|$when]] this method will return
+     * `false` regardless of the `when` condition because it may be called be
+     * before the model is loaded with data.
+     *
      * @param string $attribute attribute name
      * @return boolean whether the attribute is required
      */
@@ -446,7 +449,6 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
                 return true;
             }
         }
-
         return false;
     }
 
@@ -482,7 +484,6 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
     public function getAttributeLabel($attribute)
     {
         $labels = $this->attributeLabels();
-
         return isset($labels[$attribute]) ? $labels[$attribute] : $this->generateAttributeLabel($attribute);
     }