import math
from mech_workbench.model_utils import is_finite, safe_mean

def test_is_finite():
    assert is_finite(1.0)
    assert is_finite(0)
    assert is_finite(-5.5)
    assert not is_finite(math.nan)
    assert not is_finite(math.inf)
    assert not is_finite(-math.inf)
    assert not is_finite("abc")
    assert not is_finite(None)

def test_safe_mean():
    assert safe_mean([1.0, 2.0, 3.0]) == 2.0
    assert safe_mean([0.0, 0.0]) == 0.0
    assert math.isnan(safe_mean([]))
    assert safe_mean([-1.0, 1.0]) == 0.0