def test_distance_only_measured_to_next_matching_byte():
b = ByteStream()
b.write(b"abcabc")
distance = b.until(97)
assert distance == 1
distance = b.until(98)
assert distance == 2
distance = b.until(99)
assert distance == 3
def test_can_find_bytes():
b = ByteStream()
b.write(b"abc")
distance = b.until(97)
assert distance == 1
distance = b.until(98)
assert distance == 2
distance = b.until(99)
assert distance == 3
def test_can_find_bytes_several_chunks_ahead():
b = ByteStream()
b.write(b"xxx")
b.write(b"xxx")
b.write(b"xxx")
b.write(b"abc")
distance = b.until(97)
assert distance == 10
distance = b.until(98)
assert distance == 11
distance = b.until(99)
assert distance == 12
def test_distance_changes_after_read():
b = ByteStream()
b.write(b"abcbca")
distance = b.until(97)
assert distance == 1
distance = b.until(98)
assert distance == 2
distance = b.until(99)
assert distance == 3
b.read(3)
distance = b.until(97)
assert distance == 3
distance = b.until(98)
assert distance == 1
distance = b.until(99)
assert distance == 2
def test_cannot_find_anything_if_empty():
b = ByteStream()
distance = b.until(97)
assert distance is None
def test_cannot_find_byte_not_written():
b = ByteStream()
b.write(b"abc")
distance = b.until(100)
assert distance is None