Add getRouteCollection()

This method will be used by the new hooks to create the initial builder
that is passed to the application's routing hook.

src/Routing/Router.php

@@ -1059,6 +1059,16 @@ public static function routes()
         return static::$_collection->routes();
     }
 
+    /**
+     * Get the RouteCollection inside the Router
+     *
+     * @return \Cake\Routing\RouteCollection
+     */
+    public static function getRouteCollection()
+    {
+        return static::$_collection;
+    }
+
     /**
      * Get a MiddlewareQueue of middleware that matches the provided path.
      *

tests/TestCase/Routing/RouterTest.php

@@ -19,6 +19,7 @@
 use Cake\Http\MiddlewareQueue;
 use Cake\Http\ServerRequest;
 use Cake\Http\ServerRequestFactory;
+use Cake\Routing\RouteCollection;
 use Cake\Routing\Router;
 use Cake\Routing\Route\Route;
 use Cake\TestSuite\TestCase;
@@ -3363,6 +3364,18 @@ public function testGetMatchingMiddleware()
         $this->assertCount(1, $result);
     }
 
+    /**
+     * Test getting the route collection
+     *
+     * @return void
+     */
+    public function testGetRouteCollection()
+    {
+        $collection = Router::getRouteCollection();
+        $this->assertInstanceOf(RouteCollection::class, $collection);
+        $this->assertCount(0, $collection->routes());
+    }
+
     /**
      * Connect some fallback routes for testing router behavior.
      *