Added MiddlewarePipeInterface as abstraction layer for MiddlewarePipe

docs/book/v3/migration.md

@@ -75,6 +75,9 @@ internal logic.
 - `Next::handle()`: the method now provides a return typehint of
   `Psr\Http\Message\ResponseInterface`.
 
+- `MiddlewarePipe` class is marked now as `final` and implements new interface
+  `MiddlewarePipeInterface.`
+
 - `MiddlewarePipe::pipe()`: reduces the number of arguments to one, which now
   typehints against `Psr\Http\Server\MiddlewareInterface`. This means the method
   can no longer be used to segregate middleware by path. If you want to do that,
@@ -88,6 +91,11 @@ internal logic.
 
 ### Class additions
 
+- `Zend\Stratigility\MiddlewarePipeInterface` extends
+  `Psr\Http\Server\MiddlewareInterface` and `Psr\Http\Server\RequestHandlerInterface`
+  and define method `pipe(Psr\Http\Server\MiddlewareInterface $middleware) : void`.
+  It is implemented by `MiddlewarePipe`, because this is marked as `final` class.
+
 - `Zend\Stratigility\Middleware\HostMiddlewareDecorator` allows you to segregate
   middleware by a static host name. This allows executing middleware only
   if a particular host matches.

src/MiddlewarePipe.php

@@ -28,7 +28,7 @@
  *
  * @see https://github.com/sencha/connect
  */
-final class MiddlewarePipe implements MiddlewareInterface, RequestHandlerInterface
+final class MiddlewarePipe implements MiddlewarePipeInterface
 {
     /**
      * @var SplQueue

src/MiddlewarePipeInterface.php

@@ -0,0 +1,17 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-stratigility for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-stratigility/blob/master/LICENSE.md New BSD License
+ */
+declare(strict_types=1);
+
+namespace Zend\Stratigility;
+
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+
+interface MiddlewarePipeInterface extends MiddlewareInterface, RequestHandlerInterface
+{
+    public function pipe(MiddlewareInterface $middleware) : void;
+}

test/MiddlewarePipeTest.php

@@ -14,10 +14,14 @@
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\MiddlewareInterface;
 use Psr\Http\Server\RequestHandlerInterface;
+use ReflectionClass;
+use ReflectionMethod;
+use ReflectionObject;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequest as Request;
 use Zend\Stratigility\Exception;
 use Zend\Stratigility\MiddlewarePipe;
+use Zend\Stratigility\MiddlewarePipeInterface;
 
 class MiddlewarePipeTest extends TestCase
 {
@@ -179,4 +183,31 @@ public function testHandleProcessesEnqueuedMiddleware()
 
         $this->assertSame($response, $pipeline->handle($this->request));
     }
+
+    public function testMiddlewarePipeOnlyImplementsMiddlewarePipeInterfaceApi()
+    {
+        $pipeline = new MiddlewarePipe();
+
+        $r = new ReflectionObject($pipeline);
+        $methods = $r->getMethods(ReflectionMethod::IS_PUBLIC);
+        $actual = [];
+        foreach ($methods as $method) {
+            if (strpos($method->getName(), '__') !== 0) {
+                $actual[] = $method->getName();
+            }
+        }
+        sort($actual);
+
+        $interfaceReflection = new ReflectionClass(MiddlewarePipeInterface::class);
+        $interfaceMethods = $interfaceReflection->getMethods(ReflectionMethod::IS_PUBLIC);
+        $expected = [];
+        foreach ($interfaceMethods as $method) {
+            $expected[] = $method->getName();
+        }
+        sort($expected);
+
+        self::assertTrue($r->isFinal());
+        self::assertEquals($expected, $actual);
+        self::assertInstanceOf(MiddlewarePipeInterface::class, $pipeline);
+    }
 }