How to unit-test an abstract class, when its constructor executes its abstract method(-s)?

Question

1.08M viewsSeptember 10, 2022abstract-class php phpunit unit-testing zend-framework2

1

automatix September 7, 2022 0 Comments

I’m writing PHPUnit unit tests for this Zend Framework 2 class:

<?php
namespace MyNamespaceInputFilter;

use ZendInputFilterInput as ZendInput;
use ZendInputFilterFactory;
use ZendInputFilterInputInterface;
use MyNamespaceExceptionInvalidParameterException;

abstract class AbstractInput extends ZendInput
{
    final public function __construct()
    {
        // The constructor uses/executes the abstract method getInputSpecification().
        $this->init($this->getInputSpecification());
    }
    public function merge(InputInterface $input)
    {
        $mergedInput = parent::merge($input);
        $mergedInput->setFallbackValue($input->getFallbackValue());
        return $mergedInput;
    }
    public function isValid()
    {
        $this->injectNotEmptyValidator();
        $validator = $this->getValidatorChain();
        $value     = $this->getValue();
        $result    = $validator->isValid($value, $context);
        return $result;
    }
    protected function init($inputSpecification)
    {
        $factory = new Factory();
        $tempInput = $factory->createInput($inputSpecification);
        $this->merge($tempInput);
    }
    abstract protected function getInputSpecification();
    public function getFinalValue($param)
    {
        $finalValue = null;
        if (empty($param) || $this->getValue() === '') {
            if ($this->getFallbackValue() !== null) {
                $finalValue = $this->getFallbackValue();
            } else {
                throw new InvalidParameterException('The parameter ' . $this->name . ' must be set!');
            }
        } else {
            if ($this->isValid()) {
                $finalValue = $this->getValue();
            } else {
                throw new InvalidParameterException('The parameter ' . $this->name . ' is invalid!');
            }
        }
        return $finalValue;
    }
}

and get a problem with this. This code

// ...
class AbstractInputTest extends TestCase
{
    // ...
    public function setUp()
    {
        $stub = $this->getMockForAbstractClass('MyNamespaceInputFilterAbstractInput');
        $stub
            ->expects($this->any())
            ->method('getInputSpecification')
            ->will($this->returnValue(array())
        );
        // ...
    }
    // ...
}

causes an error:

$ phpunit SgtrTest/InputFilter/AbstractInputTest.php PHPUnit 3.7.21 by Sebastian Bergmann.

Configuration read from /path/to/project/tests/phpunit.xml

E…

Time: 1 second, Memory: 7,00Mb

There was 1 error:

1) SgtrTestInputFilterAbstractInputTest::testMerge
ZendInputFilterExceptionInvalidArgumentException:
ZendInputFilterFactory::createInput expects an array or Traversable;
received “NULL”

/path/to/project/vendor/ZF2/library/Zend/InputFilter/Factory.php:98
/path/to/project/vendor/SGTR/library/MyNamespace/InputFilter/AbstractInput.php:72
/path/to/project/vendor/SGTR/library/MyNamespace/InputFilter/AbstractInput.php:31
/path/to/project/tests/SgtrTest/InputFilter/AbstractInputTest.php:20

FAILURES! Tests: 4, Assertions: 0, Errors: 1.

I undestand, why the error is thrown. Bu how to to resolve this in another way?

1 Answer

score 1 · Answer 1 · 2022-09-07T02:24:51+00:00

In my test, I create a quick class extending the abstract class, then I test the concrete methods in that class.

class TestAbstractInput extends AbstractInput
{
    ...
}

class AbstractInputTest extends TestCase
{
    // ...
    public function setUp()
    {
        $this->TestClassObject = new TestAbstractInput();
    }

    public function test_isValid()
    {
        $this->assertEquals(1, $this->TestClassObject->isValid);
    }
}

After this, you can then use the either a Mock object of the Abstract class created in the test, or mock the Abstract class as you have done.