Added tests for Http2Middleware

* Added unit tests for middleware
* Message handling code

tests/Http2MiddlewareTest.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace NoccyLabs\React\Http2;
+
+use NoccyLabs\React\Http2\Frame\SettingsFrame;
+use PHPUnit\Framework\Attributes\CoversClass;
+use Psr\Http\Message\ResponseInterface;
+use React\Http\Message\Response;
+use React\Http\Message\ServerRequest;
+
+#[CoversClass(Http2Middleware::class)]
+class Http2MiddlewareTest extends \PHPUnit\Framework\TestCase
+{
+
+    public function testInvalidUpgradeRequests()
+    {
+        $request = new ServerRequest("GET", "/", [
+            "Upgrade" => "h2",
+            "x-forwarded-proto" => "http"
+        ]);
+
+        $middleware = new Http2Middleware();
+
+        /** @var ResponseInterface $response */
+        $response = $middleware($request);
+
+        $this->assertEquals(Response::STATUS_BAD_REQUEST, $response->getStatusCode());
+    }
+
+    public function testHandlingUpgradeRequest()
+    {
+        $http2settings = new SettingsFrame();
+        $http2settings->set(SettingsFrame::SETTINGS_MAX_CONCURRENT_STREAMS, 64);
+
+        $request = new ServerRequest("GET", "/", [
+            "Upgrade" => "h2c",
+            "Connection" => "upgrade",
+            "x-forwarded-proto" => "http",
+            "HTTP2-Settings" => $http2settings->toBinary(),
+        ]);
+
+        $middleware = new Http2Middleware();
+
+        /** @var ResponseInterface $response */
+        $response = $middleware($request);
+
+        $this->assertEquals(Response::STATUS_SWITCHING_PROTOCOLS, $response->getStatusCode());
+    }
+
+}