/**
  * test allowNull getter and setter
  */
 function testStringVR_allowNull()
 {
     $svr = new StringValidationRule('A_String', null, '^[abc]+$');
     $this->assertFalse($svr->getAllowNull());
     $svr->setAllowNull(true);
     $this->assertTrue($svr->getAllowNull());
     $svr->setAllowNull('not a boolean!');
     // will set it false
     $this->assertFalse($svr->getAllowNull());
 }