Add MCPProtocolTest and enhance test structure

Introduce unit tests for MCPProtocol to verify transport behavior. Update .gitignore for PHPUnit coverage and improve SseControllerTest mocks and comments for clarity.

Author: klapaudius

.gitignore

@@ -30,3 +30,4 @@ phpstan.neon
 testbench.yaml
 /docs
 /coverage
+/phpunit.coverage.xml

tests/Controllers/SseControllerTest.php

@@ -4,15 +4,18 @@
 
 use KLP\KlpMcpServer\Controllers\SseController;
 use KLP\KlpMcpServer\Server\MCPServerInterface;
+use PHPUnit\Framework\Attributes\Small;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\StreamedResponse;
 
+#[Small]
 class SseControllerTest extends TestCase
 {
     private SseController $controller;
 
-    private MCPServerInterface $mockServer;
+    private MCPServerInterface|MockObject $mockServer;
 
     protected function setUp(): void
     {
@@ -44,7 +47,7 @@ public function test_handle_executes_server_connect(): void
 
         $response = $this->controller->handle($request);
 
-        // Ensure response stream executes the connect callback
+        // Ensure the response stream executes the connect callback
         ob_start();
         $response->sendContent();
         ob_end_clean();

tests/Protocol/MCPProtocolTest.php

@@ -0,0 +1,140 @@
+<?php
+
+namespace KLP\KlpMcpServer\Tests\Protocol;
+
+use Exception;
+use KLP\KlpMcpServer\Protocol\MCPProtocol;
+use KLP\KlpMcpServer\Transports\TransportInterface;
+use PHPUnit\Framework\Attributes\Small;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+#[Small]
+class MCPProtocolTest extends TestCase
+{
+    private TransportInterface|MockObject $mockTransport;
+    private MCPProtocol $mcpProtocol;
+
+    protected function setUp(): void
+    {
+        $this->mockTransport = $this->createMock(TransportInterface::class);
+        $this->mcpProtocol = new MCPProtocol($this->mockTransport);
+    }
+
+    /**
+     * Test that connect method starts the transport
+     */
+    public function testConnectStartsTransport(): void
+    {
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('start');
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('isConnected')
+            ->willReturn(false);
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('close');
+
+        $this->mcpProtocol->connect();
+    }
+
+    /**
+     * Test connect processes messages when transport is connected
+     */
+    public function testConnectProcessesMessages(): void
+    {
+        $messages = ['message1', 'message2'];
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('start');
+
+        $this->mockTransport
+            ->method('isConnected')
+            ->willReturn(true, false);
+
+        $this->mockTransport
+            ->method('receive')
+            ->willReturn($messages);
+
+        $this->mockTransport
+            ->expects($matcher = $this->exactly(count($messages)))
+            ->method('send')
+            ->with($this->callback(function ($message) use ($messages, $matcher) {
+                $this->assertEquals($messages[$matcher->numberOfInvocations()-1], $message);
+                return true;
+            }));
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('close');
+
+        $this->mcpProtocol->connect();
+    }
+
+    /**
+     * Test that connect method ignores null messages without sending
+     */
+    public function testConnectIgnoresNullMessages(): void
+    {
+        $messages = [null, 'validMessage', null];
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('start');
+
+        $this->mockTransport
+            ->method('isConnected')
+            ->willReturn(true, false);
+
+        $this->mockTransport
+            ->method('receive')
+            ->willReturn($messages);
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('send')
+            ->with('validMessage');
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('close');
+
+        $this->mcpProtocol->connect();
+    }
+
+    /**
+     * Test that connect sends messages using the transport's send method
+     */
+    public function testConnectSendsMessages(): void
+    {
+        $messages = ['test_message'];
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('start');
+
+        $this->mockTransport
+            ->method('isConnected')
+            ->willReturn(true, false);
+
+        $this->mockTransport
+            ->method('receive')
+            ->willReturn($messages);
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('send')
+            ->with($messages[0]);
+
+        $this->mockTransport
+            ->expects($this->once())
+            ->method('close');
+
+        $this->mcpProtocol->connect();
+    }
+}