Add standard middleware to handle missing routes

Each framework offers a different request handler or middleware to be
used as last item in the middleware pipeline, which is called when no
route has been matched by the router.

This allows us to delegate the formatting of such error to an error
handling middleware, granting more flexibility to people.

src/MissingRouteDispatching.php

@@ -0,0 +1,17 @@
+<?php
+declare(strict_types=1);
+
+namespace Chimera\Routing;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+
+final class MissingRouteDispatching implements MiddlewareInterface
+{
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        throw NoRouteMatched::fromRequest($request);
+    }
+}

src/NoRouteMatched.php

@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace Chimera\Routing;
+
+use Chimera\Exception;
+use Psr\Http\Message\ServerRequestInterface;
+use RuntimeException;
+use function sprintf;
+
+final class NoRouteMatched extends RuntimeException implements Exception
+{
+    private const HTTP_STATUS = 404;
+
+    public static function fromRequest(ServerRequestInterface $request): self
+    {
+        return new self(sprintf('Cannot %s %s', $request->getMethod(), $request->getUri()), self::HTTP_STATUS);
+    }
+}

tests/MissingRouteDispatchingTest.php

@@ -0,0 +1,36 @@
+<?php
+declare(strict_types=1);
+
+namespace Chimera\Routing\Tests;
+
+use Chimera\Routing\MissingRouteDispatching;
+use Chimera\Routing\NoRouteMatched;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Server\RequestHandlerInterface;
+use Zend\Diactoros\ServerRequest;
+
+/**
+ * @coversDefaultClass \Chimera\Routing\MissingRouteDispatching
+ */
+final class MissingRouteDispatchingTest extends TestCase
+{
+    /**
+     * @test
+     *
+     * @covers ::process
+     * @covers \Chimera\Routing\NoRouteMatched::fromRequest
+     */
+    public function processShouldThrowAnExceptionWithRequestInformation(): void
+    {
+        $middleware = new MissingRouteDispatching();
+
+        $this->expectException(NoRouteMatched::class);
+        $this->expectExceptionCode(404);
+        $this->expectExceptionMessage('Cannot GET /testing');
+
+        $middleware->process(
+            new ServerRequest([], [], '/testing', 'GET'),
+            $this->createMock(RequestHandlerInterface::class)
+        );
+    }
+}