[Phpmyadmin-devel] Refactoring: Displaying query results

[Chanaka Dharmarathna]

Hi Dieter,

> I almost reduce the use of super global variables inside functions of
> > PMA_DisplayResults class.
> > Most of the fields are set while executing the getTable() function since
> > they cannot set while executing the constructor.
> >
> > Now I'm move into writing tests.
> > I am facing to a problem with writing tests.
> > How can I access or set the private variables, by a test ?
> > The already existed tests also failing due to this change.
> > Your suggestions will very helpful.
>
>
>
> I didn't have a look at the current tests and at PMA_DisplayResults
> class, so I won't be able to go into specifics about your tests, but I
> will try to answer your questions, and point you in a direction.
>
> Accessing or setting private variables in a class/method is not
> possible during a unit test.
> The idea of unit tests is to test the functionality of a class method
> or global function by testing the output of it, or catching errors.
> You expect a certain behaviour of the method/function depending on the
> value of the input parameters (or environmental states, like global
> variables, database content, or config settings).
> So basically you think of all different situations that can affect the
> behaviour of the method/function, define what kind of result this
> would give and write a test that sets up the situation and test
> (assert) the output of the function/method.
>
> When writing unit tests, you should keep in mind that you are only
> testing the behaviour of that function/method. Any functions/methods
> used by a function/method should be tested seperately. By which I mean
> that you must assume when testing a function/method that the
> functions/methods that are used in that method, work correctly.
> To make things easier for you, you can define stubs/mocks [0] that
> replace the methods/functions used in a function/method you are
> testing. This way you don't have to set up a complete environment, but
> can concentrate on what the function/method does.
>
> As an example
>
> If you have a class that gets values from a database :
>
> class DbValues
> {
>    private $_values;
>
>    __construct()
>    {
>        $this->_values = array();
>    }
>
>    public function getValuesFromDb()
>    {
>        // functionality making a connection to a database, executing a
> query and setting the resulting values to $_values.
>    }
>
>    public function getValues()
>    {
>        return $this->_values;
>    }
>
>   public function count()
>   {
>      return count($this->getValues());
>   }
> }
>
>
> And you want to test the behaviour of the count() method. The only way
> to populate the _values variable in this example would be by setting
> up a database with different sets of values, for each case you want to
> test and call the getValuesFromDb() method, OR, you can  define a stub
> that replaces the getValues() method and let it return an array with
> the necessary amount of values (depending on what you want to test).
> This way you avoid having to set up a complicated testing environment,
> when testing a single class method. (Note : when testing the
> getValuesFromDb() method you will probably have to set up a database,
> but that's because that method is all about connecting to a database
> and getting data from it, but all other methods in this class can
> assume that the getValuesFromDb works, so there is no need to
> replicate the complicated test environment every time)
>
> I suggest you read up a bit on testing class methods and the use of
> stubs/mocks. I hope my example didn't confuse you too much.
>
> [0]
> http://www.phpunit.de/manual/current/en/test-doubles.html#test-doubles.stubs
>
>
Thank you very much for spending your time for clarify this with valuable
and enough information.
I completely agree with you, on writing unit tests independent/separate
from another layer/function.
Mock objects/stubs are helpful in that case.

At the moment there are around 25 private fields in PMA_DisplayResults
class.
What I am thinking of implement getter setter methods for all those and use
getters and setters where needed.
In that way I will be able to set those private fields even from the tests.
What do you think on this ?

Regards !
-- 
____________________________________

Chanaka Indrajith
Bsc.Computer Engineering Undergraduate
Faculty of Engineering
University of Peradeniya
Sri Lanka
____________________________________
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