def test_valid_valuation_satisfies(self):
variable = Variable('a')
mapping = {variable: True}
v = Valuation(mapping)
c = Clause([Literal(variable)])
self.assertTrue(c.is_satisfied(v))
def test_invalid_valuation_does_not_satisfy(self):
variable = Variable('a')
v = Valuation({variable: False})
c = Clause([Literal(variable)])
self.assertFalse(c.is_satisfied(v))
def test_is_satisfied_with_invalid_argument_type_fails(self):
c = Clause([Literal(Variable('a'))])
self.assertRaises(TypeError, lambda l: c.is_satisfied({}))
