def METHOD_NAME():
    """Test case where there is no variance in model outputs for grouped factors."""
    def mock_model(X):
        r, _ = X.shape
        return np.array([0.4] * r)
    problem = {
        "num_vars": 3,
        "names": ["x1", "x2", "x3"],
        "groups": ["A", "B", "A"],
        "bounds": [[0, 1], [0, 1], [0, 1]],
    }
    N = 256
    param_values = saltelli.sample(problem, N, calc_second_order=False)
    model_results = mock_model(param_values)
    Si = sobol.analyze(problem, model_results, calc_second_order=False)
    assert np.all(
        Si["S1"] == 0.0
    ), "Constant outputs should produce 0 first order sensitivity"
    assert np.all(
        Si["ST"] == 0.0
    ), "Constant outputs should produce 0 total order sensitivity"
    assert np.all(Si["S1_conf"] == 0.0), "Constant outputs should produce 0 CI"
    assert np.all(Si["ST_conf"] == 0.0), "Constant outputs should produce 0 CI"