fix: attach() closes executor on failure; guard session adoption

tests/unit/test_reattach.py

@@ -5,6 +5,8 @@ from wabot.hosts import ReattachingRemote, attach, build_options
 
 class TestReattachingRemote:
     def test_adopts_session_id_without_creating_a_session(self):
+        # constructing against a closed port (127.0.0.1:1) proves no HTTP happens
+        # until the first command
         driver = ReattachingRemote(
             "http://127.0.0.1:1", "saved-session-id", options=build_options("chromium")
         )
@@ -39,3 +41,16 @@ class TestAttach:
     def test_returns_none_when_server_is_unreachable(self):
         # no server on port 1: connection refused is immediate; attach must not raise
         assert attach("http://127.0.0.1:1", "sid", "chromium") is None
+
+    def test_dead_session_closes_executor(self, monkeypatch):
+        from selenium.webdriver.remote.remote_connection import RemoteConnection
+
+        closed = []
+        monkeypatch.setattr(RemoteConnection, "close", lambda self: closed.append(1))
+
+        def boom(self):
+            raise WebDriverException("invalid session id")
+
+        monkeypatch.setattr(ReattachingRemote, "current_url", property(boom))
+        assert attach("http://127.0.0.1:1", "sid", "chromium") is None
+        assert closed == [1]  # executor was closed, not leaked