{

private const TIMEOUT = 5;

private const BOTH = 'both';

private const HANDSHAKE_ONLY = 'handshake-only';

private const MODERN_ONLY = 'modern-only';

private ?Process $server = null;

private string $sessions;

private int $port;

protected function setUp(): void

{

$this->sessions = sys_get_temp_dir().'/mcp-integration-sessions-'.getmypid();

$this->port = 9600 + (getmypid() % 200);

}

protected function tearDown(): void

{

$this->server?->stop();

foreach (glob($this->sessions.'/*') ?: [] as $file) {

@unlink($file);

}

@rmdir($this->sessions);

}

/**

public static function provideNegotiations(): iterable

{

yield 'a client and a server speaking both eras' => [self::BOTH, ProtocolVersion::V2026_07_28, ProtocolVersion::V2026_07_28];

yield 'a handshake-era client and a server speaking both eras' => [self::BOTH, ProtocolVersion::V2025_11_25, ProtocolVersion::V2025_11_25];

yield 'a client speaking both eras and a server without the modern era' => [self::HANDSHAKE_ONLY, ProtocolVersion::V2026_07_28, ProtocolVersion::V2025_11_25];

yield 'a handshake-era client and a server without the modern era' => [self::HANDSHAKE_ONLY, ProtocolVersion::V2025_06_18, ProtocolVersion::V2025_06_18];

yield 'a client speaking both eras and a server with only the modern era' => [self::MODERN_ONLY, ProtocolVersion::V2026_07_28, ProtocolVersion::V2026_07_28];

}

#[DataProvider('provideNegotiations')]

#[TestDox('$_dataName settle on a revision and talk')]

public function testNegotiatesAndTalks(string $server, ?ProtocolVersion $clientVersion, ProtocolVersion $expected): void

{

$this->start($server);

$builder = $this->clientBuilder();

if (null !== $clientVersion) {

$builder->setProtocolVersion($clientVersion);

}

$client = $builder->build();

$started = microtime(true);

$client->connect($this->transport());

$this->assertLessThan(self::TIMEOUT - 1, microtime(true) - $started);

$this->assertSame($expected, $client->getProtocolVersion());

$this->assertSame('integration-server', $client->getServerInfo()?->name);

$this->assertSame('Be brief.', $client->getInstructions());

$result = $client->callTool('echo', ['text' => 'hello']);

$this->assertInstanceOf(TextContent::class, $result->content[0]);

$this->assertSame('hello', $result->content[0]->text);

$client->disconnect();

}

#[TestDox('a handshake-era client is told which revisions a server with only the modern era speaks')]

public function testHandshakeClientLearnsWhatAModernOnlyServerSpeaks(): void

{

$this->start(self::MODERN_ONLY);

$client = $this->clientBuilder()->setProtocolVersion(ProtocolVersion::V2025_11_25)->setMaxRetries(0)->build();

$this->expectException(ConnectionException::class);

$this->expectExceptionMessage('it supports 2026-07-28');

$client->connect($this->transport());

}

#[TestDox('a modern-only client refuses a server without the modern era')]

public function testModernOnlyClientRefusesAHandshakeOnlyServer(): void

{

$this->start(self::HANDSHAKE_ONLY);

$client = $this->clientBuilder()->setProtocolVersion(ProtocolVersion::V2026_07_28)->setFallbackProtocolVersion(null)->setMaxRetries(0)->build();

$this->expectException(ConnectionException::class);

$this->expectExceptionMessage('without a handshake fallback: "server/discover" was answered with error -32022');

$client->connect($this->transport());

}

private function clientBuilder(): ClientBuilder

{

return Client::builder()

->setClientInfo('integration-client', '1.0.0')

->setInitTimeout(self::TIMEOUT)

->setRequestTimeout(self::TIMEOUT);

}

private function transport(): HttpTransport

{

return new HttpTransport(\sprintf('http://127.0.0.1:%d/', $this->port));

}

private function start(string $server): void

{

@mkdir($this->sessions);

$this->server = new Process(

[\PHP_BINARY, '-S', \sprintf('127.0.0.1:%d', $this->port), __DIR__.'/Fixture/http.php'],

env: [

'MCP_INTEGRATION_SESSIONS' => $this->sessions,

'MCP_INTEGRATION_HANDSHAKE_ONLY' => self::HANDSHAKE_ONLY === $server ? '1' : '',

'MCP_INTEGRATION_MODERN_ONLY' => self::MODERN_ONLY === $server ? '1' : '',

],

);

$this->server->start();

$deadline = microtime(true) + 5;

while (microtime(true) < $deadline) {

if (@fsockopen('127.0.0.1', $this->port, $errno, $error, 0.1)) {

return;

}

usleep(50_000);

}

$this->fail(\sprintf('The fixture server did not start: %s', $this->server->getErrorOutput()));

}