Test whether optimizer gets caching and fallback downloads

tests/php/src/Optimizer/OptimizerServiceTest.php

@@ -2,17 +2,23 @@
 
 namespace AmpProject\AmpWP\Tests\Optimizer;
 
+use AmpProject\AmpWP\AmpWpPlugin;
 use AmpProject\AmpWP\Optimizer\OptimizerService;
+use AmpProject\AmpWP\RemoteRequest\CachedRemoteGetRequest;
 use AmpProject\AmpWP\Tests\Helpers\AssertContainsCompatibility;
 use AmpProject\Dom\Document;
 use AmpProject\Optimizer\ErrorCollection;
 use AmpProject\Optimizer\TransformationEngine;
+use \AmpProject\AmpWP\Tests\Helpers\PrivateAccess;
+use AmpProject\RemoteGetRequest;
+use AmpProject\RemoteRequest\FallbackRemoteGetRequest;
 use PHPUnit\Framework\TestCase;
 
 /** @coversDefaultClass \AmpProject\AmpWP\Optimizer\OptimizerService */
 final class OptimizerServiceTest extends TestCase {
 
 	use AssertContainsCompatibility;
+	use PrivateAccess;
 
 	const HERO_IMAGE_MARKUP = '<amp-img data-hero src="https://example.com/image.jpg" width="500" height="500"></amp-img>';
 
@@ -37,4 +43,27 @@ public function test_method_forwarding() {
 		$this->assertStringContains( 'transformed="self;v=1"', $output );
 		$this->assertTrue( $html_errors->has( 'TooManyHeroImages' ) );
 	}
+
+	/**
+	 * @covers \AmpProject\AmpWP\Optimizer\OptimizerService::__construct()
+	 * @covers \AmpProject\AmpWP\AmpWpPlugin::get_delegations()
+	 */
+	public function test_caching_and_fallback_are_enabled() {
+		$plugin = new AmpWpPlugin();
+		$plugin->register_services();
+
+		$injector  = $plugin->get_container()->get( 'injector' );
+		$optimizer = $injector->make( OptimizerService::class );
+
+		$transformation_engine = $this->get_private_property( $optimizer, 'transformation_engine' );
+		$this->assertInstanceOf( TransformationEngine::class, $transformation_engine );
+
+		$remote_request = $this->get_private_property( $transformation_engine, 'remoteRequest' );
+		$this->assertInstanceOf( RemoteGetRequest::class, $remote_request );
+		$this->assertInstanceOf( CachedRemoteGetRequest::class, $remote_request );
+
+		$cached_remote_request = $this->get_private_property( $remote_request, 'remote_request' );
+		$this->assertInstanceOf( RemoteGetRequest::class, $cached_remote_request );
+		$this->assertInstanceOf( FallbackRemoteGetRequest::class, $cached_remote_request );
+	}
 }