CONSOLE ERROR: line 15: WebSocket connection to 'ws://localhost:8880/handshake-fail-by-extensions-header' failed: Error during WebSocket handshake: Found an unsupported extension 'x-foo' in 'Sec-WebSocket-Extensions' header
Test whether WebSocket handshake fails if the server sends Sec-WebSocket-Extensions header.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".

PASS onerror() was called
PASS closeEvent.wasClean is false
PASS successfullyParsed is true

TEST COMPLETE