def test_literal_choice_can_parse_both_possibilities(runner, a, b):
# we must order the two strings because of the possibility that a
# can be a prefix of b or the other way around
p = choice(
try_parser(literal(a)),
literal(b),
) if len(a) > len(b) else choice(
try_parser(literal(b)),
literal(a),
)
assert runner(p, a).value == a
assert runner(p, b).value == b
def test_failure_of_choice_of_3_literals_should_contain_all_3_literal():
p = choice(
literal('first'),
choice(
literal('second'),
literal('third')
)
)
with pytest.raises(ParsingFailed) as err:
run_parser(p, 'xxxxxxxxxxxxxxxx')
error_message = str(err.value)
assert 'first' in error_message
assert 'second' in error_message
assert 'third' in error_message
def test_that_error_message_order_is_preserved_with_3_choices():
p = choice(
literal('first'),
choice(
literal('second'),
literal('third'),
)
)
with pytest.raises(ParsingFailed) as err:
run_parser(p, 'xxxxxxxxxxxxxx')
error_message = str(err.value)
assert 'second' in error_message.split('first')[1]
assert 'third' in error_message.split('first')[1]
assert 'first' in error_message.split('second')[0]
assert 'third' in error_message.split('second')[1]
def test_choice_throws_ParsingFailed_when_both_choices_fail(runner):
p = choice(
literal('a'),
literal('b'),
)
with pytest.raises(ParsingFailed):
runner(p, 'c')
def test_failure_of_choice_of_2_literals_should_contain_both_literals():
p = choice(
literal('first_literal'),
literal('second_literal'),
)
with pytest.raises(ParsingFailed) as err:
run_parser(p, 'xxxxxxxxxxxxxxxxxxx')
assert 'first_literal' in str(err.value)
assert 'second_literal' in str(err.value)
def test_that_error_message_respects_ordering_of_failing_choices():
p = choice(
literal('first'),
literal('second'),
)
with pytest.raises(ParsingFailed) as err:
run_parser(p, 'xxxxxxxxxxxxxx')
error_message = str(err.value)
assert 'second' in error_message.split('first')[1]
assert 'first' in error_message.split('second')[0]
def test_choice_should_not_retry_if_the_parser_after_choice_fails(runner):
p = choice(
literal('a'), # this should match the incomming input
literal('aa'),
)
p = chain(
p,
literal('b')
)
with pytest.raises(ParsingFailed):
runner(p, 'aab')
def test_choice_can_be_chained_1000_times(runner):
c = choice(
literal('a'),
literal('b'),
)
p = unit('')
for i in range(0, 1000):
p = bind(
p,
lambda x: c,
)
assert runner(p, 'a' * 999 + 'b').value == 'b'
def test_if_a_choice_failes_in_the_middle_of_chain_it_retries_other_option(
runner
):
p = choice(
try_parser(chain(
literal('a'),
literal('a')
)),
chain(
literal('a'),
literal('b'),
)
)
assert runner(p, 'ab').value == 'b'