PHPUnit: Doing assertions on non-public variables

Question

Suppose I have a class with a private property and associated public getter and setter. I want to test with PHPUnit that the property gets the correct value after the sette

Answer 1

For testing properties, I'd make the same arguments I make then talking about testing private methods.

You usually don't want to do this.

It's about testing observable behavior.

If you rename all your properties or decide to store them into an array you should not need to adapt your tests at all. You want your tests to tell you that everything still works! When you need to change the tests to make sure everything still works you lose all the benefits as you also could make an error changing the tests.

So, all in all, you lose the value of you test suite!

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Just testing the get/set combinations would be ok enough but usually not every setter should have a getter and just creating them for testing is not a nice thing ether.

Usually, you set some stuff and then tell the method to DO (behavior) something. Testing for that (that the class does what is should do) is the best option for testing and should make testing the properties superfluous.

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If you really want to do that there is the setAccessible functionality in PHP reflections API but I can't make up an example where I find this desirable

Finding unused properties to catch bugs / issues like this one:

The PHP Mess Detector As a UnusedPrivateField Rule

class Something
{
    private static $FOO = 2; // Unused
    private $i = 5; // Unused
    private $j = 6;
    public function addOne()
    {
        return $this->j++;
    }
}

This will generate two warnings for you because the variables are never accessed