from src.rules.fractions import match_constant_division, division_by_one, \
        division_of_zero
from src.possibilities import Possibility as P
from tests.test_rules_poly import tree
from tests.rulestestcase import RulesTestCase


class TestRulesFractions(RulesTestCase):

    def test_match_constant_division(self):
        a, zero = tree('a,0')

        root = a / zero
        self.assertRaises(ZeroDivisionError, match_constant_division, root)

        root = a / 1
        possibilities = match_constant_division(root)
        self.assertEqualPos(possibilities, [P(root, division_by_one, (a,))])

        root = zero / a
        possibilities = match_constant_division(root)
        self.assertEqualPos(possibilities, [P(root, division_of_zero)])

    def test_division_by_one(self):
        a = tree('a')
        root = a / 1

        self.assertEqualNodes(division_by_one(root, (a,)), a)

    def test_division_of_zero(self):
        a, zero = tree('a,0')
        root = zero / a

        self.assertEqualNodes(division_of_zero(root, ()), zero)