def driver(event_chain: AppHarness) -> Generator[WebDriver, None, None]:
    """Get an instance of the browser open to the event_chain app.

    Args:
        event_chain: harness for EventChain app

    Yields:
        WebDriver instance.
    """
    assert event_chain.app_instance is not None, "app is not running"
    driver = event_chain.frontend()
    try:
        yield driver
    finally:
        driver.quit()
Get an instance of the browser open to the event_chain app.

    Args:
        event_chain: harness for EventChain app

    Yields:
        WebDriver instance.
    
tests/integration/test_event_chain.py