def test_invalid_scalar_index(adata, index):
    # https://github.com/theislab/anndata/issues/619
    with pytest.raises(IndexError, match=r".*index.* out of range\."):
        _ = adata[index]
def allowed_file(filename):
    return '.' in filename and \
           filename.rsplit('.', 1)[1] in app.config.get('ALLOWED_EXTENSIONS')