import os
import sys
import pytest

import matplotlib.backends.backend_webagg_core
from matplotlib.testing import subprocess_run_for_testing


@pytest.mark.parametrize("backend", ["webagg", "nbagg"])
def test_webagg_fallback(backend):
    pytest.importorskip("tornado")
    if backend == "nbagg":
        pytest.importorskip("IPython")
    env = dict(os.environ)
    if sys.platform != "win32":
        env["DISPLAY"] = ""

    env["MPLBACKEND"] = backend

    test_code = (
        "import os;"
        + f"assert os.environ['MPLBACKEND'] == '{backend}';"
        + "import matplotlib.pyplot as plt; "
        + "print(plt.get_backend());"
        f"assert '{backend}' == plt.get_backend().lower();"
    )
    subprocess_run_for_testing([sys.executable, "-c", test_code], env=env, check=True)


def test_webagg_core_no_toolbar():
    fm = matplotlib.backends.backend_webagg_core.FigureManagerWebAgg
    assert fm._toolbar2_class is None