def test_read() -> None:
original = BytesIO(b"xxxxabcdefghijyyyyy")
proxy = IOProxy(original, 4, 14)
# read all
original.seek(2)
proxy.seek(0)
assert proxy.read() == b"abcdefghij"
assert original.tell() == 14
proxy.seek(4)
assert proxy.read() == b"efghij"
assert original.tell() == 14
# read partial
original.seek(2)
proxy.seek(6)
assert proxy.read(3) == b"ghi"
assert original.tell() == 13
assert proxy.read(3) == b"j"
assert original.tell() == 14
assert proxy.read(3) == b""
assert original.tell() == 14
assert proxy.read(3) == b""
assert original.tell() == 14
# with original seek
original.seek(2)
proxy.seek(4)
original.seek(1)
assert proxy.read() == b"efghij"
assert original.tell() == 14
def test_seek() -> None:
original = Mock()
proxy = IOProxy(original, 4, 14)
assert proxy.tell() == 0
assert proxy.seek(7) == 7
assert proxy.tell() == 7
assert not original.method_calls # did not touch original