php-sdk/tests/Unit/Server/BuilderTest.php

<?php

/*
 * This file is part of the official PHP MCP SDK.
 *
 * A collaboration between Symfony and the PHP Foundation.
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Mcp\Tests\Unit\Server;

use Mcp\Capability\Registry\ElementReference;
use Mcp\Capability\Registry\ReferenceHandlerInterface;
use Mcp\Exception\LogicException;
use Mcp\Schema\Content\TextContent;
use Mcp\Schema\Extension\Apps\McpApps;
use Mcp\Schema\JsonRpc\Response;
use Mcp\Schema\Request\CallToolRequest;
use Mcp\Schema\ServerCapabilities;
use Mcp\Server;
use Mcp\Server\Handler\Request\CallToolHandler;
use Mcp\Server\Handler\Request\InitializeHandler;
use Mcp\Server\Session\SessionInterface;
use PHPUnit\Framework\Attributes\TestDox;
use PHPUnit\Framework\TestCase;

final class BuilderTest extends TestCase
{
    #[TestDox('setReferenceHandler() returns the builder for fluent chaining')]
    public function testSetReferenceHandlerReturnsSelf(): void
    {
        $referenceHandler = $this->createStub(ReferenceHandlerInterface::class);

        $builder = Server::builder();
        $result = $builder->setReferenceHandler($referenceHandler);

        $this->assertSame($builder, $result);
    }

    #[TestDox('build() succeeds with a custom ReferenceHandler')]
    public function testBuildWithCustomReferenceHandler(): void
    {
        $referenceHandler = $this->createStub(ReferenceHandlerInterface::class);

        $server = Server::builder()
            ->setServerInfo('test', '1.0.0')
            ->setReferenceHandler($referenceHandler)
            ->build();

        $this->assertInstanceOf(Server::class, $server);
    }

    #[TestDox('build() succeeds without a custom ReferenceHandler (uses default)')]
    public function testBuildWithoutCustomReferenceHandler(): void
    {
        $server = Server::builder()
            ->setServerInfo('test', '1.0.0')
            ->build();

        $this->assertInstanceOf(Server::class, $server);
    }

    #[TestDox('Custom ReferenceHandler is used when calling a tool')]
    public function testCustomReferenceHandlerIsUsedForToolCalls(): void
    {
        $referenceHandler = $this->createMock(ReferenceHandlerInterface::class);
        $referenceHandler->expects($this->once())
            ->method('handle')
            ->willReturnCallback(static function (ElementReference $reference, array $arguments): string {
                return 'intercepted';
            });

        $server = Server::builder()
            ->setServerInfo('test', '1.0.0')
            ->setReferenceHandler($referenceHandler)
            ->addTool(static fn (): string => 'original', name: 'test_tool', description: 'A test tool')
            ->build();

        $result = $this->callTool($server, 'test_tool');

        $this->assertSame('intercepted', $result);
    }

    #[TestDox('A pre-built instance handler with constructor dependencies is registered and invoked on that instance')]
    public function testPreBuiltInstanceHandlerIsInvokedOnTheGivenInstance(): void
    {
        // The handler's constructor requires an argument the container-less
        // `new $className()` fallback can never satisfy. If the tool call
        // succeeds, it can only be because the pre-built instance — carrying
        // its injected dependency — was the one invoked.
        $handler = new GreetingService('World');

        $server = Server::builder()
            ->setServerInfo('test', '1.0.0')
            ->addTool(handler: [$handler, 'greet'], name: 'greet', description: 'Greets using the injected name')
            ->build();

        $result = $this->callTool($server, 'greet');

        $this->assertSame('Hello, World', $result);
    }

    #[TestDox('enableExtension() registers an extension and announces its capability payload')]
    public function testEnableExtensionRegistersExtension(): void
    {
        $server = Server::builder()
            ->setServerInfo('test', '1.0.0')
            ->enableExtension(new McpApps())
            ->build();

        $capabilities = $this->extractServerCapabilities($server);

        $this->assertNotNull($capabilities->extensions);
        $this->assertArrayHasKey(McpApps::EXTENSION_ID, $capabilities->extensions);
        $this->assertSame(['mimeTypes' => [McpApps::MIME_TYPE]], $capabilities->extensions[McpApps::EXTENSION_ID]);
    }

    #[TestDox('enableExtension() throws when the same extension is enabled twice')]
    public function testEnableExtensionRejectsDuplicate(): void
    {
        $this->expectException(LogicException::class);
        $this->expectExceptionMessage(McpApps::EXTENSION_ID);

        Server::builder()->enableExtension(new McpApps(), new McpApps());
    }

    #[TestDox('enableExtension() extensions are merged into capabilities set via setCapabilities()')]
    public function testEnableExtensionMergesIntoCustomCapabilities(): void
    {
        $server = Server::builder()
            ->setServerInfo('test', '1.0.0')
            ->setCapabilities(new ServerCapabilities(tools: true))
            ->enableExtension(new McpApps())
            ->build();

        $capabilities = $this->extractServerCapabilities($server);

        $this->assertNotNull($capabilities->extensions);
        $this->assertArrayHasKey(McpApps::EXTENSION_ID, $capabilities->extensions);
    }

    private function extractServerCapabilities(Server $server): ServerCapabilities
    {
        $protocol = (new \ReflectionClass($server))->getProperty('protocol')->getValue($server);
        $requestHandlers = (new \ReflectionClass($protocol))->getProperty('requestHandlers')->getValue($protocol);

        foreach ($requestHandlers as $handler) {
            if ($handler instanceof InitializeHandler) {
                return $handler->configuration->capabilities;
            }
        }

        $this->fail('InitializeHandler not found in request handlers');
    }

    private function callTool(Server $server, string $toolName): mixed
    {
        $protocol = (new \ReflectionClass($server))->getProperty('protocol')->getValue($server);
        $requestHandlers = (new \ReflectionClass($protocol))->getProperty('requestHandlers')->getValue($protocol);

        foreach ($requestHandlers as $handler) {
            if ($handler instanceof CallToolHandler) {
                $request = CallToolRequest::fromArray([
                    'jsonrpc' => '2.0',
                    'method' => 'tools/call',
                    'id' => 'test-1',
                    'params' => ['name' => $toolName, 'arguments' => []],
                ]);
                $session = $this->createStub(SessionInterface::class);

                $response = $handler->handle($request, $session);

                if ($response instanceof Response) {
                    $content = $response->result->content[0] ?? null;

                    return $content instanceof TextContent ? $content->text : null;
                }

                $this->fail('Expected Response, got '.$response::class);
            }
        }

        $this->fail('CallToolHandler not found in request handlers');
    }
}

/**
 * A handler whose constructor dependency cannot be satisfied by the
 * container-less `new $className()` fallback, so it must be registered as a
 * pre-built instance.
 */
final class GreetingService
{
    public function __construct(private string $name)
    {
    }

    public function greet(): string
    {
        return 'Hello, '.$this->name;
    }
}