def test_iter_cnf_clauses_not_cnf(self):
"""Test attempting iter_cnf_clauses when not in CNF."""
b = BooleanExpression('A or !!B')
self.assertFalse(b.is_cnf)
with self.assertRaises(RequiresNormalFormError):
for clause in b.iter_cnf_clauses():
pass
def test_simple_iter_cnf(self):
"""Test basic expression iter_cnf_clauses functionality."""
b = BooleanExpression('(A or B) and (C or D) and (E or F)')
self.assertTrue(b.is_cnf)
self.assertFalse(b.is_dnf)
clauses = b.iter_cnf_clauses()
self.assertEqual(
repr(next(clauses)),
'<BooleanExpression "A or B">')
self.assertEqual(
repr(next(clauses)),
'<BooleanExpression "C or D">')
self.assertEqual(
repr(next(clauses)),
'<BooleanExpression "E or F">')
with self.assertRaises(StopIteration):
next(clauses)