Receive session.created event once connected

See #15 (comment)

src/main/php/com/openai/realtime/RealtimeApi.class.php

@@ -1,9 +1,10 @@
 <?php namespace com\openai\realtime;
 
+use lang\IllegalStateException;
 use text\json\Json;
-use util\URI;
 use util\data\Marshalling;
 use util\log\Traceable;
+use util\URI;
 use websocket\WebSocket;
 
 /**
@@ -29,11 +30,26 @@ public function setTrace($cat) {
     $this->cat= $cat;
   }
 
-  /** Opens the underlying websocket, optionally passing headers */
-  public function connect(array $headers= []): self {
+  /**
+   * Opens the underlying websocket, optionally passing headers
+   *
+   * Verifies a `session.created` event is received. This is sent by the server
+   * as soon as the connection is successfully established. Provides a connection-
+   * specific ID that may be useful for debugging or logging.
+   *
+   * @return var
+   * @throws lang.IllegalStateException
+   */
+  public function connect(array $headers= []) {
     $this->cat && $this->cat->info($this->ws->socket(), $this->ws->path(), $headers);
     $this->ws->connect($headers);
-    return $this;
+
+    $event= $this->receive();
+    if ('session.created' === ($event['type'] ?? null)) return $event;
+
+    $error= 'Unexpected handshake event "'.($event['type'] ?? '(null)').'"';
+    $this->ws->close(4007, $error);
+    throw new IllegalStateException($error);
   }
 
   /** Returns whether the underlying websocket is connected */

src/test/php/com/openai/unittest/RealtimeApiTest.class.php

@@ -1,9 +1,11 @@
 <?php namespace com\openai\unittest;
 
 use com\openai\realtime\RealtimeApi;
-use test\{Assert, Test, Values};
+use lang\IllegalStateException;
+use test\{Assert, Expect, Test, Values};
 
 class RealtimeApiTest {
+  const SESSION_CREATED= '{"type": "session.created"}';
 
   /** Returns authentications */
   private function authentications(): iterable {
@@ -25,15 +27,15 @@ public function initially_not_connected() {
 
   #[Test]
   public function connect() {
-    $c= new RealtimeApi(new TestingSocket());
+    $c= new RealtimeApi(new TestingSocket([self::SESSION_CREATED]));
     $c->connect();
 
     Assert::true($c->connected());
   }
 
   #[Test, Values(from: 'authentications')]
   public function passing_headers($kind, $headers) {
-    $s= new TestingSocket();
+    $s= new TestingSocket([self::SESSION_CREATED]);
 
     $c= new RealtimeApi($s);
     $c->connect($headers);
@@ -43,7 +45,7 @@ public function passing_headers($kind, $headers) {
 
   #[Test]
   public function close() {
-    $c= new RealtimeApi(new TestingSocket());
+    $c= new RealtimeApi(new TestingSocket([self::SESSION_CREATED]));
     $c->connect();
     $c->close();
 
@@ -52,23 +54,26 @@ public function close() {
 
   #[Test]
   public function initial_handshake() {
-    $c= new RealtimeApi(new TestingSocket([
-      '{"type": "session.created"}',
-    ]));
-    $c->connect();
+    $c= new RealtimeApi(new TestingSocket([self::SESSION_CREATED]));
+    $session= $c->connect();
+
+    Assert::equals(['type' => 'session.created'], $session);
+  }
 
-    Assert::equals(['type' => 'session.created'], $c->receive());
+  #[Test, Expect(class: IllegalStateException::class, message: 'Unexpected handshake event "error"')]
+  public function unexpected_handshake() {
+    $c= new RealtimeApi(new TestingSocket(['{"type":"error"}']));
+    $c->connect();
   }
 
   #[Test]
   public function update_session() {
     $c= new RealtimeApi(new TestingSocket([
-      '{"type": "session.created"}',
+      self::SESSION_CREATED,
       '{"type": "session.update", "session": {"instructions": "You are TestGPT"}}',
       '{"type": "session.updated"}',
     ]));
     $c->connect();
-    $c->receive();
     $c->send(['type' => 'session.update', 'session' => ['instructions' => 'You are TestGPT']]);
 
     Assert::equals(['type' => 'session.updated'], $c->receive());
@@ -77,12 +82,11 @@ public function update_session() {
   #[Test]
   public function transmit() {
     $c= new RealtimeApi(new TestingSocket([
-      '{"type": "session.created"}',
+      self::SESSION_CREATED,
       '{"type": "conversation.item.create", "item": {"type": "message"}}',
       '{"type": "conversation.item.created"}',
     ]));
     $c->connect();
-    $c->receive();
     $response= $c->transmit(['type' => 'conversation.item.create', 'item' => ['type' => 'message']]);
 
     Assert::equals(['type' => 'conversation.item.created'], $response);