test_empirical_formula.py

"""Test parsing and serde of empirical chemical formulae."""
import pytest

from gemd.json import dumps, loads
from gemd.entity.value.empirical_formula import EmpiricalFormula
from gemd.entity.bounds import CompositionBounds


def test_all_elements():
    """Check that list of all elements exists and has some select examples."""
    for el in ["H", "He", "C", "Si", "Mg", "Al", "Co", "Ce"]:
        assert el in EmpiricalFormula.all_elements(), "Couldn't find {} in all_elements".format(el)
    assert len(EmpiricalFormula.all_elements()) == 120, "Expected 120 elements"


def test_json():
    """Check that we can json ser/de round-robin."""
    empirical = EmpiricalFormula("Al94.5Si5.5")
    copy = loads(dumps(empirical))
    assert(copy == empirical)


def test_formula_setter():
    """Check that we can set the formula."""
    test_formula = "CsPbBr1.5I1.5"
    test_empirical = EmpiricalFormula()
    assert test_empirical.formula is None
    test_empirical.formula = test_formula
    assert test_empirical.formula == test_formula


def test_invalid_formula():
    """Check that an invalid formula throws a TypeError."""
    with pytest.raises(TypeError):
        EmpiricalFormula(formula={"Al": 2, "O": 3})
    with pytest.raises(ValueError):
        EmpiricalFormula(formula="WoRdS")


def test_contains():
    """Test that bounds know if a Value is contained within it."""
    bounds = CompositionBounds({"C", "H", "O", "N"})
    assert bounds.contains(EmpiricalFormula('C2H5OH')._to_bounds())
    assert not bounds.contains(EmpiricalFormula('NaCl')._to_bounds())