Add support for ignore property exist test for interface

1. it makes no sens to check if an interface exists in case it's an interface
2. If the property is not recognized as one and there is no identifier, then
   api platform will not be able to call the DataProvider for a given item
   and interface as a resource is an incomplete feature.

Author: Nek-

features/main/table_inheritance.feature

@@ -327,3 +327,38 @@ Feature: Table inheritance
        "required": ["hydra:member"]
      }
      """
+
+  Scenario: Get an interface resource item
+    When I send a "GET" request to "/resource_interfaces/some-id"
+    Then the response status code should be 200
+    And the response should be in JSON
+    And the header "Content-Type" should be equal to "application/ld+json; charset=utf-8"
+    And the JSON should be valid according to this schema:
+    """
+    {
+      "type": "object",
+      "properties": {
+        "context": {
+          "type": "string",
+          "pattern": "ResourceInterface$"
+        },
+        "@id": {
+          "type": "string",
+          "pattern": "resource_interfaces$"
+        },
+        "@type": {
+          "type": "string",
+          "pattern": "^ResourceInterface$"
+        },
+        "foo": {
+          "type": "string",
+          "required": "true"
+        },
+        "fooz": {
+          "type": "string",
+          "required": "true",
+          "pattern": "fooz"
+        }
+      }
+    }
+    """

src/Metadata/Property/Factory/ExtractorPropertyMetadataFactory.php

@@ -48,9 +48,11 @@ public function create(string $resourceClass, string $property, array $options =
             }
         }
 
+        $isInterface = \interface_exists($resourceClass);
+
         if (
-            !property_exists($resourceClass, $property) ||
-            !$propertyMetadata = $this->extractor->getResources()[$resourceClass]['properties'][$property] ?? false
+            !property_exists($resourceClass, $property) && !$isInterface ||
+            empty($propertyMetadata = $this->extractor->getResources()[$resourceClass]['properties'][$property] ?? [])
         ) {
             return $this->handleNotFound($parentPropertyMetadata, $resourceClass, $property);
         }

tests/Fixtures/FileConfigurations/interface_resource.yml

@@ -1,2 +1,8 @@
 resources:
-    'ApiPlatform\Core\Tests\Fixtures\DummyResourceInterface': ~
+    'ApiPlatform\Core\Tests\Fixtures\DummyResourceInterface':
+        properties:
+            something:
+                identifier: true
+            somethingElse:
+                writable: false
+                readable: true

tests/Fixtures/TestBundle/DataProvider/ResourceInterfaceImplementationDataProvider.php

@@ -28,7 +28,11 @@ public function supports(string $resourceClass, string $operationName = null, ar
 
     public function getItem(string $resourceClass, $id, string $operationName = null, array $context = [])
     {
-        return (new ResourceInterfaceImplementation())->setFoo('single item');
+        if ('some-id' === $id) {
+            return (new ResourceInterfaceImplementation())->setFoo('single item');
+        }
+
+        return null;
     }
 
     public function getCollection(string $resourceClass, string $operationName = null)

tests/Fixtures/TestBundle/OtherResources/ResourceInterface.php

@@ -16,4 +16,6 @@
 interface ResourceInterface
 {
     public function getFoo(): string;
+
+    public function getFooz(): string;
 }

tests/Fixtures/TestBundle/OtherResources/ResourceInterfaceImplementation.php

@@ -51,4 +51,9 @@ public function getBar(): ?string
     {
         return $this->bar;
     }
+
+    public function getFooz(): string
+    {
+        return 'fooz';
+    }
 }

tests/Fixtures/TestBundle/Resources/config/api_resources.yml

@@ -7,3 +7,7 @@ resources:
         collectionOperations:
             get:
                 method: 'GET'
+
+        properties:
+            foo:
+                identifier: true

tests/Metadata/Property/Factory/ExtractorPropertyMetadataFactoryTest.php

@@ -21,6 +21,7 @@
 use ApiPlatform\Core\Metadata\Property\Factory\PropertyMetadataFactoryInterface;
 use ApiPlatform\Core\Metadata\Property\PropertyMetadata;
 use ApiPlatform\Core\Metadata\Property\SubresourceMetadata;
+use ApiPlatform\Core\Tests\Fixtures\DummyResourceInterface;
 use ApiPlatform\Core\Tests\Fixtures\TestBundle\Entity\FileConfigDummy;
 use ApiPlatform\Core\Tests\Fixtures\TestBundle\Entity\RelatedDummy;
 use Doctrine\Common\Collections\ArrayCollection;
@@ -237,4 +238,18 @@ public function testCreateWithMalformedYaml()
 
         (new ExtractorPropertyMetadataFactory(new YamlExtractor([$configPath])))->create(FileConfigDummy::class, 'foo');
     }
+
+    public function testItExtractPropertiesFromInterfaceResources()
+    {
+        $configPath = __DIR__.'/../../../Fixtures/FileConfigurations/interface_resource.yml';
+
+        $propertyMetadataFactory = new ExtractorPropertyMetadataFactory(new YamlExtractor([$configPath]));
+        $metadataSomething = $propertyMetadataFactory->create(DummyResourceInterface::class, 'something');
+        $metadataSomethingElse = $propertyMetadataFactory->create(DummyResourceInterface::class, 'somethingElse');
+
+        $this->assertInstanceOf(PropertyMetadata::class, $metadataSomething);
+        $this->assertInstanceOf(PropertyMetadata::class, $metadataSomethingElse);
+        $this->assertTrue($metadataSomething->isIdentifier());
+        $this->assertFalse($metadataSomethingElse->isWritable());
+    }
 }