@pytest.mark.skipif(skip_cupy_test, reason='CuPy is not installed.')
def test_set_backend():
    backend.set_backend('numpy')
    assert isinstance(backend, NumpyBackend)
    backend.set_backend('cupy')
    assert isinstance(backend, CuPyBackend)
@pytest.mark.skipif(skip_cupy_test, reason='CuPy is not installed.')
def test_set_backend():
    backend.set_backend('numpy')
    assert isinstance(backend, NumpyBackend)
    backend.set_backend('cupy')
    assert isinstance(backend, CuPyBackend)