Feature: Add deferred resolution to model factory definitions

[kjohnson]

Description

This PR adds deferred resolution to model factory definitions, such as nested model factories, so that defaults can be overridden without instantiating unused model instances.

Affects

Updates Give\Framework\Models\Factories\ModelFactory::makeInstance() to support resolving attributes that are callable.

Visuals

public function definition(): array
{
    return [
        'title' => __('GiveWP Campaign', 'give'),
        'formId' => DonationForm::factory()->createAndResolveTo('id'),
    ];
}

Testing Instructions

This feature is covered by unit tests and does not have a customer facing application.

Pre-review Checklist

• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Self Review of code and UX completed

[JasonTheAdams]

Great work, @kjohnson! A couple little suggestions! 😄

[JasonTheAdams]

I wonder if the is_callable() is too generic? For example, model properties can be a class (say a VO), and if that class instance is invokable, then that would pass as is_callable() in which case it would be called here unintentionally.

I think it's safer to use $attribute instanceof Closure instead. I can't think of a time wherein a model property would be a closure, as that's not something persistable.

[kjohnson]

Good point. I added a test to confirm and the test failed. Updating the resolver to check for a Closure type passed the test.

    public function testDoesNotResolveInvokableClasses()
    {
        $factory = new class(MockModelWithInvokableProperty::class) extends ModelFactory {
            public function definition(): array {
                return [
                    'invokable' => new class extends MockInvokableClass {
                        public function __invoke() {
                            throw new \Exception('Invokable classes should not be resolved by factories.');
                        }
                    },
                ];
            }
        };

        $object = $factory->make();

        $this->assertInstanceOf(MockInvokableClass::class, $object->invokable);
    }

[kjohnson]

Resolved, see dd89630.

[JasonTheAdams]

Nice work, @kjohnson! 👍

Would you be willing, on your next Fun Friday, to add this to the StellarWP library? We really need to move over to that library as to avoid drifting apart.

[kjohnson]

Would you be willing, on your next Fun Friday, to add this to the StellarWP library?

Yeah, that sounds like a good next step.