Allow varying ResourceGeneratorFactory behavior

This patch adds a new optional constructor argument to the
`ResourceGeneratorFactory`, a string `$linkGeneratorServiceName`. By
default, it uses `Zend\Expressive\Hal\LinkGenerator` for the value.
Users can, however, specify an alternate service class. This allows
users to vary the `ResourceGenerator` per module or path-segregated
middleware pipeline:

```php
// In configuration:
return [
    'dependencies' => [
        'factories' => [
            \Api\Router::class => FastRouteRouterFactory::class,
            \Api\RouteMiddleware::class => new RouteMiddlewareFactory(\Api\Router::class),
            \Api\UrlHelper::class => new UrlHelperFactory('/api', \Api\Router::class),
            \Api\UrlHelperMiddleware::class => new UrlHelperMiddlewareFactory(\Api\UrlHelper::class),
            \Api\UrlGenerator::class => new ExpressiveUrlGeneratorFactory(\Api\UrlHelper::class),
            \Api\LinkGenerator::class => new LinkGeneratorFactory(\Api\UrlGenerator::class),
            \Api\ResourceGenerator::class => new ResourceGeneratorFactory(\Api\LinkGenerator::class),
        ],
    ],
],
```

The factory implements `__set_state()`, allowing serialization via
`var_export()` (the mechanism used by the default expressive
configuration caching mechanism).

Author: weierophinney

src/ResourceGeneratorFactory.php

@@ -17,12 +17,33 @@
 
 class ResourceGeneratorFactory
 {
+    /** @var string */
+    private $linkGeneratorServiceName;
+
+    /**
+     * Allow serialization
+     */
+    public static function __set_state(array $data) : self
+    {
+        return new self(
+            $data['linkGeneratorServiceName'] ?? LinkGenerator::class
+        );
+    }
+
+    /**
+     * Allow varying behavior based on link generator service name.
+     */
+    public function __construct(string $linkGeneratorServiceName = LinkGenerator::class)
+    {
+        $this->linkGeneratorServiceName = $linkGeneratorServiceName;
+    }
+
     public function __invoke(ContainerInterface $container) : ResourceGenerator
     {
         $generator = new ResourceGenerator(
             $container->get(Metadata\MetadataMap::class),
             $container->get(HydratorPluginManager::class),
-            $container->get(LinkGenerator::class)
+            $container->get($this->linkGeneratorServiceName)
         );
 
         $this->injectStrategies($container, $generator);

test/ResourceGeneratorFactoryTest.php

@@ -146,7 +146,7 @@ public function testFactoryWithRouteBasedCollectionStrategy()
         );
 
         $this->container->get(RouteBasedCollectionStrategy::class)->willReturn(
-            $this->prophesize(RouteBasedCollectionStrategy::class)
+            $this->prophesize(RouteBasedCollectionStrategy::class)->reveal()
         );
 
         $object = new ResourceGeneratorFactory();
@@ -162,4 +162,41 @@ public function testFactoryWithRouteBasedCollectionStrategy()
             $registeredStrategies[RouteBasedCollectionMetadata::class]
         );
     }
+
+    public function testConstructorAllowsSpecifyingLinkGeneratorServiceName()
+    {
+        $container = $this->prophesize(ContainerInterface::class);
+
+        $container
+            ->get(Metadata\MetadataMap::class)
+            ->willReturn($this->prophesize(Metadata\MetadataMap::class)->reveal());
+
+        $container
+            ->get(HydratorPluginManager::class)
+            ->willReturn($this->prophesize(ContainerInterface::class)->reveal());
+
+        $linkGenerator = $this->prophesize(LinkGenerator::class)->reveal();
+        $container
+            ->get(CustomLinkGenerator::class)
+            ->willReturn($linkGenerator);
+
+        $container->has('config')->willReturn(false);
+
+        $factory = new ResourceGeneratorFactory(CustomLinkGenerator::class);
+
+        $generator = $factory($container->reveal());
+
+        $this->assertInstanceOf(ResourceGenerator::class, $generator);
+        $this->assertAttributeSame($linkGenerator, 'linkGenerator', $generator);
+    }
+
+    public function testFactoryIsSerializable()
+    {
+        $factory = ResourceGeneratorFactory::__set_state([
+            'linkGeneratorServiceName' => CustomLinkGenerator::class,
+        ]);
+
+        $this->assertInstanceOf(ResourceGeneratorFactory::class, $factory);
+        $this->assertAttributeSame(CustomLinkGenerator::class, 'linkGeneratorServiceName', $factory);
+    }
 }