[Phpmyadmin-devel] Mocking static methods - Unit tests

[Madhura Jayaratne]

On Tue, Jul 9, 2013 at 5:49 PM, Ayush Chaudhary <ayushchd at gmail.com> wrote:

> On Tuesday, 9 July 2013 at 5:58 PM, Madhura Jayaratne wrote:
>
>
>
>
> On Tue, Jul 9, 2013 at 2:21 PM, Ayush Chaudhary <ayushchd at gmail.com>wrote:
>
>  Hi,
>
> I have been writing Unit Tests for classes and libraries under
> libraries/config/*. For isolation between different libraries, its
> preferred to mock certain functions. Since some of the code is functional,
> I tried to convert (for a start) libraries/config/validate.lib.php into a
> class with static methods.
>
> However, the issue here is that mocking static methods is not really
> possible with PHPUnit and there are a few workarounds I came across and
> would like to know which one should we go for, or if there is anything
> better that can be done.
>
> So, while the writer of PHPUnit specifies how to mock static methods
> here[0], its only possible if the static calls are to the same class.
>
> For example, for testing FormDisplay::_validate, I need to mock
> PMA_config_validate. After I convert validate.lib.php to a class, say,
> PMA_Validator, I will have to mock PMA_Validator::config_validate, but the
> above solution won't work here (since PMA_Validator cannot be mocked). A
> workaround for this could be to pass the mocked static class as mentioned
> in [0] to the FormDisplay.class.php and make all static calls via that
> class.
>
> For this, we could have something of this sort in the constructor of
> FormDisplay:
>
> if (defined('TESTSUITE'))
> $this->validator = $GLOBALS['dummyValidator'] or $this->validator =
> <mockedClassPassedInTheArgument>
> else
> $this->validator = 'PMA_Validator'
>
> and the calls can be made like:
>
> $caller = $this->validator; // $this->validator::config_validate won't work
> $caller:config_validate();
>
> Another solution could be what is mentioned in a blog here[1]. The problem
> with this solution is that the file, FormDisplay.class.php would include
> and hence declare the PMA_Validator class before our test suite tries to
> (re)declare it by extending MockProxy class.
>
> In either case, it looks like some sort of modification would be needed to
> test these classes.
>
> Please advice.
>
> [0]
> http://sebastian-bergmann.de/archives/883-Stubbing-and-Mocking-Static-Methods.html
> [1] http://www.deanspot.org/content/mocking-static-method-calls-phpunit
>
>
> As Sebastian Bergmann says, "static methods are death to testability".
> This makes me wonder what disadvantages we would have if we make the
> methods of PMA_Validator class non-static and use instantiated object
> of PMA_Validator class to do the validations?
>
> I doubt there would be any disadvantages. In any case, from the POV of
> Unit Testing, we will have to include the instantiated object or the class
> name, as a member of the class that calls the respective methods (in this
> example. FormDisplay)
>
> Further, I'd like to know how useful this statement on PHP.net can be in
> this context:
>
> 'A property declared as static can not be accessed with an instantiated
> class object (*though a static method can*)'
>
> I guess this [1] will help

[1]
http://stackoverflow.com/questions/14331450/a-property-declared-as-static-can-not-be-accessed-with-an-instantiated-class-obj


-- 
Thanks and Regards,

Madhura Jayaratne
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