traits-with-protected-methods.md

Testing traits with protected methods in PHPUnit

Traits provide a mechanism for reusing sets of methods in independent classes.

PHPUnit introduced support for traits with version 3.8, but similar to testing “regular” classes, private/protected functions are not accessible by default. As PHPUnit_Framework_TestCase::getMockForTrait() fails in conjunction with class reflection, the suggested approach uses PHPUnit_Framework_TestCase::getObjectForTrait() and the ReflectionMethod class to make the desired methods accessible for testing.

Example

Given a trait

trait ExampleTrait
{
    protected function doTheMagic($parameter)
    {
        ...
        return $returnValue;
    }
}

the protected method can be accessed in a PHPUnit test like

class ExampleTest extends \PHPUnit_Framework_TestCase
{
    /**
     * @test
     */
    public function testTheMagic()
    {
        $exampleTrait = $this->getObjectForTrait(ExampleTrait::class);

        $doTheMagicReflection = new \ReflectionMethod(get_class($exampleTrait), 'doTheMagic');
        $doTheMagicReflection->setAccessible(true);

        $this->assertEquals(
            $expectedReturnValue,
            $doTheMagicReflection->invoke($exampleTrait, $testParameter)
        );
    }
}

Resources

Inspired by: Testing traits with non-public methods