def test_logic_onearg():
assert And() is True
assert Or() is False
assert And(T) == T
assert And(F) == F
assert Or(T) == T
assert Or(F) == F
assert And('a') == 'a'
assert Or('a') == 'a'
def test_logic_not():
assert Not(False) is True
assert Not('a') != '~a'
assert Not('~a') != 'a'
# NOTE: we may want to change default Not behaviour and put this
# functionality into some method.
assert Not(And('a', 'b')) == Or(Not('a'), Not('b'))
assert Not(Or('a', 'b')) == And(Not('a'), Not('b'))
pytest.raises(ValueError, lambda: Not(ValueError))
def test_FactRules_parse():
f = FactRules('a -> b')
assert f.prereq == {'b': {'a'}, 'a': {'b'}}
f = FactRules('a -> ~b')
assert f.prereq == {'b': {'a'}, 'a': {'b'}}
f = FactRules('~a -> b')
assert f.prereq == {'b': {'a'}, 'a': {'b'}}
f = FactRules('~a -> ~b')
assert f.prereq == {'b': {'a'}, 'a': {'b'}}
f = FactRules('~z == nz')
assert f.prereq == {'z': {'nz'}, 'nz': {'z'}}
pytest.raises(ValueError, lambda: FactRules('a ? b'))
f = FactRules('a -> b & ~b') # trivial test
assert not f.prereq
# tautologies
assert not FactRules('a -> a | b').prereq
# XXX: We don't support non-atomic left operands, so use Prover directly
p = Prover()
p.process_rule(And('a', 'b'), 'a')
p.process_rule(Or('a', 'b'), 'a')
assert not p.proved_rules
def test_logic_combine_args():
assert And('a', 'b', 'a') == And('a', 'b')
assert Or('a', 'b', 'a') == Or('a', 'b')
assert And(And('a', 'b'), And('c', 'd')) == And('a', 'b', 'c', 'd')
assert Or(Or('a', 'b'), Or('c', 'd')) == Or('a', 'b', 'c', 'd')
assert Or('t', And('n', 'p', 'r'), And('n', 'r'), And('n', 'p', 'r'), 't', And('n', 'r')) == \
Or('t', And('n', 'p', 'r'), And('n', 'r'))
def test_logic_fromstring():
s = Logic.fromstring
assert s('a') == 'a'
assert s('~a') == Not('a')
assert s('a & b') == And('a', 'b')
assert s('a | b') == Or('a', 'b')
assert s('a | b & c') == And(Or('a', 'b'), 'c')
assert s('a & b | c') == Or(And('a', 'b'), 'c')
assert s('a & b & c') == And('a', 'b', 'c')
assert s('a | b | c') == Or('a', 'b', 'c')
pytest.raises(ValueError, lambda: s('| a'))
pytest.raises(ValueError, lambda: s('& a'))
pytest.raises(ValueError, lambda: s('a | | b'))
pytest.raises(ValueError, lambda: s('a | & b'))
pytest.raises(ValueError, lambda: s('a & & b'))
pytest.raises(ValueError, lambda: s('a |'))
pytest.raises(ValueError, lambda: s('a|b'))
pytest.raises(ValueError, lambda: s('~'))
pytest.raises(ValueError, lambda: s('~ a'))
pytest.raises(ValueError, lambda: s('a b'))
pytest.raises(ValueError, lambda: s(''))
def test_logic_expand():
t = And(Or('a', 'b'), 'c')
assert t.expand() == Or(And('a', 'c'), And('b', 'c'))
t = And(Or('a', Not('b')), 'b')
assert t.expand() == And('a', 'b')
t = And(Or('a', 'b'), Or('c', 'd'))
assert t.expand() == \
Or(And('a', 'c'), And('a', 'd'), And('b', 'c'), And('b', 'd'))
def test_logic_eval_TF():
assert And(F, F) == F
assert And(F, T) == F
assert And(T, F) == F
assert And(T, T) == T
assert Or(F, F) == F
assert Or(F, T) == T
assert Or(T, F) == T
assert Or(T, T) == T
assert And('a', T) == 'a'
assert And('a', F) == F
assert Or('a', T) == T
assert Or('a', F) == 'a'
def test_logic_xnotx():
assert And('a', Not('a')) == F
assert Or('a', Not('a')) == T