zend-diactoros is an optional dependency

composer.json

@@ -27,7 +27,6 @@
         "psr/container": "^1.0",
         "psr/http-message": "^1.0.1",
         "psr/http-server-middleware": "^1.0",
-        "zendframework/zend-diactoros": "^1.3.10",
         "zendframework/zend-expressive-router": "^3.0.0rc4",
         "zendframework/zend-expressive-template": "^2.0.0alpha1",
         "zendframework/zend-httphandlerrunner": "^1.0.1",
@@ -41,16 +40,19 @@
         "phpstan/phpstan-strict-rules": "^0.9",
         "phpunit/phpunit": "^7.0.1",
         "zendframework/zend-coding-standard": "~1.0.0",
+        "zendframework/zend-diactoros": "^1.7.1",
         "zendframework/zend-expressive-aurarouter": "^3.0.0rc3",
         "zendframework/zend-expressive-fastroute": "^3.0.0rc4",
         "zendframework/zend-expressive-zendrouter": "^3.0.0rc3",
         "zendframework/zend-servicemanager": "^2.7.8 || ^3.3"
     },
     "conflict": {
-        "container-interop/container-interop": "<1.2.0"
+        "container-interop/container-interop": "<1.2.0",
+        "zendframework/zend-diactoros": "<1.7.1"
     },
     "suggest": {
         "filp/whoops": "^2.1 to use the Whoops error handler",
+        "psr/http-message-implementation": "Please install a psr/http-message-implementation to consume Expressive; e.g., zendframework/zend-diactoros",
         "zendframework/zend-auradi-config": "^1.0 to use Aura.Di dependency injection container",
         "zendframework/zend-expressive-helpers": "^3.0 for its UrlHelper, ServerUrlHelper, and BodyParseMiddleware",
         "zendframework/zend-expressive-tooling": "For migration and development tools; require it with the --dev flag",

phpunit.xml.dist

@@ -6,11 +6,13 @@
     <testsuites>
         <testsuite name="zend-expressive-response-factory">
             <file>./test/Container/ResponseFactoryFactoryWithoutDiactorosTest.php</file>
+            <file>./test/Container/ServerRequestFactoryFactoryWithoutDiactorosTest.php</file>
             <file>./test/Container/StreamFactoryFactoryWithoutDiactorosTest.php</file>
         </testsuite>
         <testsuite name="zend-expressive">
             <directory>./test</directory>
             <exclude>./test/Container/ResponseFactoryFactoryWithoutDiactorosTest.php</exclude>
+            <exclude>./test/Container/ServerRequestFactoryFactoryWithoutDiactorosTest.php</exclude>
             <exclude>./test/Container/StreamFactoryFactoryWithoutDiactorosTest.php</exclude>
         </testsuite>
     </testsuites>

src/Container/ServerRequestFactoryFactory.php

@@ -10,6 +10,7 @@
 namespace Zend\Expressive\Container;
 
 use Psr\Container\ContainerInterface;
+use Psr\Http\Message\ServerRequestInterface;
 use Zend\Diactoros\ServerRequestFactory;
 
 /**
@@ -25,6 +26,18 @@ class ServerRequestFactoryFactory
 {
     public function __invoke(ContainerInterface $container) : callable
     {
+        if (! class_exists(ServerRequestFactory::class)) {
+            throw new Exception\InvalidServiceException(sprintf(
+                'The %1$s service must map to a factory capable of returning an'
+                . ' implementation instance. By default, we assume usage of'
+                . ' zend-diactoros for PSR-7, but it does not appear to be'
+                . ' present on your system. Please install zendframework/zend-diactoros'
+                . ' or provide an alternate factory for the %1$s service that'
+                . ' can produce an appropriate %1$s instance.',
+                ServerRequestInterface::class
+            ));
+        }
+
         return function () {
             return ServerRequestFactory::fromGlobals();
         };

test/Container/ServerRequestFactoryFactoryWithoutDiactorosTest.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-expressive for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-expressive/blob/master/LICENSE.md New BSD License
+ */
+
+declare(strict_types=1);
+
+namespace ZendTest\Expressive\Container;
+
+use PHPUnit\Framework\TestCase;
+use Prophecy\Prophecy\ObjectProphecy;
+use Psr\Container\ContainerInterface;
+use Zend\Expressive\Container\Exception\InvalidServiceException;
+use Zend\Expressive\Container\ServerRequestFactoryFactory;
+
+class ServerRequestFactoryFactoryWithoutDiactorosTest extends TestCase
+{
+    /** @var ContainerInterface|ObjectProphecy */
+    private $container;
+
+    /** @var ServerRequestFactoryFactory */
+    private $factory;
+
+    /** @var array */
+    private $autoloadFunctions = [];
+
+    protected function setUp()
+    {
+        class_exists(InvalidServiceException::class);
+
+        $this->container = $this->prophesize(ContainerInterface::class)->reveal();
+        $this->factory = new ServerRequestFactoryFactory();
+
+        $this->autoloadFunctions = spl_autoload_functions();
+        foreach ($this->autoloadFunctions as $autoloader) {
+            spl_autoload_unregister($autoloader);
+        }
+    }
+
+    private function reloadAutoloaders()
+    {
+        foreach ($this->autoloadFunctions as $autoloader) {
+            spl_autoload_register($autoloader);
+        }
+    }
+
+    public function testFactoryRaisesAnExceptionIfDiactorosIsNotLoaded()
+    {
+        $this->expectException(InvalidServiceException::class);
+        $this->expectExceptionMessage('zendframework/zend-diactoros');
+
+        try {
+            ($this->factory)($this->container);
+        } finally {
+            $this->reloadAutoloaders();
+        }
+    }
+}