@pytest.fixture(scope="session")
def jupyter_notebook(request, bokeh_server, log_file):
    """
    Starts a jupyter notebook server at the beginning of a session, and
    closes at the end of a session.

    Requires the bokeh_server fixture.

    Adds custom.js that runs all the cells on notebook opening. Cleans out
    this custom.js at the end of the test run.

    WARNING: Tramples on user's existing custom.js

    Returns the url that the jupyter notebook is running at.

    """

    # First - set-up the notebooks to run all cells when they're opened
    #
    # Can be cleaned up further to remember the user's existing customJS
    # and then restore it after the test run.
    from jupyter_core import paths
    config_dir = paths.jupyter_config_dir()

    body = """
require(["base/js/namespace", "base/js/events"], function (IPython, events) {
    events.on("kernel_ready.Kernel", function () {
        IPython.notebook.execute_all_cells();
    });
});
"""
    custom = join(config_dir, "custom")
    if not exists(custom):
        os.makedirs(custom)

    customjs = join(custom, "custom.js")
    with open(customjs, "w") as f:
        f.write(body)

    # Add in the clean-up code
    def clean_up_customjs():
        with open(customjs, "w") as f:
            f.write("")

    request.addfinalizer(clean_up_customjs)

    # Second - Run a notebook server at the examples directory
    #

    notebook_port = pytest.config.option.notebook_port

    env = os.environ.copy()
    env['BOKEH_RESOURCES'] = 'server'

    # Launch from the base directory of bokeh repo
    notebook_dir = join(dirname(__file__), pardir, pardir)

    cmd = ["jupyter", "notebook"]
    argv = ["--no-browser", "--port=%s" % notebook_port, "--notebook-dir=%s" % notebook_dir]
    jupter_notebook_url = notebook_port % "http://localhost:%d"

    try:
        proc = subprocess.Popen(cmd + argv, env=env, stdout=log_file, stderr=log_file)
    except OSError:
        write("Failed to run: %s" % " ".join(cmd + argv))
        sys.exit(1)
    else:
        # Add in the clean-up code
        def stop_jupyter_notebook():
            write("Shutting down jupyter-notebook ...")
            proc.kill()

        request.addfinalizer(stop_jupyter_notebook)

        def wait_until(func, timeout=5.0, interval=0.01):
            start = time.time()

            while True:
                if func():
                    return True
                if time.time() - start > timeout:
                    return False
                time.sleep(interval)

        def wait_for_jupyter_notebook():
            def helper():
                if proc.returncode is not None:
                    return True
                try:
                    return requests.get(jupter_notebook_url)
                except ConnectionError:
                    return False

            return wait_until(helper)

        if not wait_for_jupyter_notebook():
            write("Timeout when running: %s" % " ".join(cmd + argv))
            sys.exit(1)

        if proc.returncode is not None:
            write("Jupyter notebook exited with code " + str(proc.returncode))
            sys.exit(1)

        return jupter_notebook_url
dataset/ETHPy150Open bokeh/bokeh/tests/plugins/jupyter_notebook.py/jupyter_notebook/swapped operands of `%`