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