How to implement isValid correctly?
- by Songo
I'm trying to provide a mechanism for validating my object like this:
class SomeObject {
private $_inputString;
private $_errors=array();
public function __construct($inputString) {
$this->_inputString = $inputString;
}
public function getErrors() {
return $this->_errors;
}
public function isValid() {
$isValid = preg_match("/Some regular expression here/", $this->_inputString);
if($isValid==0){
$this->_errors[]= 'Error was found in the input';
}
return $isValid==1;
}
}
Then when I'm testing my code I'm doing it like this:
$obj = new SomeObject('an INVALID input string');
$isValid = $obj->isValid();
$errors=$obj->getErrors();
$this->assertFalse($isValid);
$this->assertNotEmpty($errors);
Now the test passes correctly, but I noticed a design problem here. What if the user called $obj->getErrors() before calling $obj->isValid()?
The test will fail because the user has to validate the object first before checking the error resulting from validation. I think this way the user depends on a sequence of action to work properly which I think is a bad thing because it exposes the internal behaviour of the class.
How do I solve this problem?
Should I tell the user explicitly to validate first? Where do I mention that?
Should I change the way I validate? Is there a better solution for this?
UPDATE:
I'm still developing the class so changes are easy and renaming functions and refactoring them is possible.
