def test_substream_with_zero_size(self):
for wrapper in (lambda f: f, TellableStream, UnseekableStream):
with self.subTest(wrapper=wrapper):
s = Substream(wrapper(io.BytesIO(b"0123456789")),
start=0,
stop=0)
self.assertEqual(b"", s.read())
def test_start_unseekable(self):
with self.subTest(wrapper=TellableStream):
with self.assertRaises(OSError):
Substream(TellableStream(io.BytesIO(b"0123456789")), 3, 6)
with self.subTest(wrapper=UnseekableStream):
s = Substream(UnseekableStream(io.BytesIO(b"0123456789")), 3, 6)
self.assertEqual(3, s.start)
self.assertEqual(0, s.tell())
def test_start_none(self):
for wrapper in (lambda f: f, TellableStream):
with self.subTest(wrapper=wrapper):
b = io.BytesIO(b"0123456789")
b.seek(2)
s = TellableStream(Substream(wrapper(b), start=None))
self.assertEqual(2, s.start)
self.assertEqual(b"23", s.read(2))
with self.subTest(wrapper=UnseekableStream):
b = io.BytesIO(b"0123456789")
b.seek(2)
s = TellableStream(Substream(UnseekableStream(b), start=None))
self.assertEqual(0, s.start)
self.assertEqual(b"23", s.read(2))
def test_tell_and_seek_set(self):
s = Substream(io.BytesIO(b"0123456789"), 3, 6)
self.assertEqual(0, s.tell())
self.assertEqual(1, s.seek(1))
self.assertEqual(b"4", s.read(1))
self.assertEqual(2, s.tell())
self.assertEqual(b"5", s.read(2))
self.assertEqual(b"", s.read(2))
def test_stream_after_closing_is_at_correct_position(self):
stream = io.BytesIO(b"0123456789")
with Substream(stream, 3, None) as s:
self.assertEqual(0, s.tell())
self.assertEqual(b"34", s.read(2))
self.assertEqual(3 + 2, stream.tell())
def test_tell_and_seek_set_unseekable(self):
s = Substream(UnseekableStream(io.BytesIO(b"012")), 3, 6)
self.assertEqual(0, s.tell())
with self.assertRaises(OSError):
self.assertEqual(1, s.seek(1))
self.assertEqual(b"0", s.read(1))
self.assertEqual(1, s.tell())
self.assertEqual(b"12", s.read(2))
self.assertEqual(b"", s.read(2))
def test_tell_and_seek_from_cur(self):
s = Substream(io.BytesIO(b"0123456789"), 3, 6)
self.assertEqual(0, s.tell())
self.assertEqual(b"34", s.read(2))
self.assertEqual(1, s.seek(-1, io.SEEK_CUR))
self.assertEqual(1, s.tell())
self.assertEqual(b"45", s.read(2))
def test_stream_that_is_closed_twice_is_at_correct_position(self):
# This can occur sometimes. Using a huge stream of bytes to attempt to trigger a
# successful seek twice.
stream = io.BytesIO(b"0123456789" * 10000)
with Substream(stream, 8000) as s:
self.assertEqual(0, s.tell())
self.assertEqual(b"0123456789" * 28, s.read(280))
s.close()
self.assertEqual(8280, stream.tell())
def test_boundaries_with_unbounded_read(self):
for wrapper in (lambda f: f, TellableStream, UnseekableStream):
with self.subTest(wrapper=wrapper):
s = Substream(wrapper(io.BytesIO(b"0123456789")), 0, 9)
self.assertEqual(b"012345678", s.read())
s = Substream(wrapper(io.BytesIO(b"0123456789")), 0, None)
self.assertEqual(b"0123456789", s.read())
def test_tell_and_seek_from_end_unbounded_substream(self):
s = Substream(io.BytesIO(b"0123456789"), 3, None)
self.assertEqual(0, s.tell())
self.assertEqual(5, s.seek(-2, io.SEEK_END))
self.assertEqual(5, s.tell())
self.assertEqual(b"89", s.read(2))
def test_tell_and_seek_from_end(self):
s = Substream(io.BytesIO(b"0123456789"), 3, 6)
self.assertEqual(0, s.tell())
self.assertEqual(2, s.seek(-1, io.SEEK_END))
self.assertEqual(2, s.tell())
self.assertEqual(b"5", s.read(2))
def test_boundaries_with_unbounded_read_other_start(self):
s = Substream(io.BytesIO(b"0123456789"), 3, 6)
self.assertEqual(b"345", s.read())
s = Substream(io.BytesIO(b"0123456789"), 3, 9)
self.assertEqual(b"345678", s.read())
s = Substream(io.BytesIO(b"0123456789"), 8, 9)
self.assertEqual(b"8", s.read())
s = Substream(io.BytesIO(b"0123456789"), 7, None)
self.assertEqual(b"789", s.read())
def test_stop_and_length(self):
with self.assertRaises(ValueError):
Substream(io.BytesIO(b"0123456789"), start=0, stop=2, length=2)
def test_negative_size(self):
with self.assertRaises(ValueError):
Substream(io.BytesIO(b"0123456789"), start=7, stop=3)
with self.assertRaises(ValueError):
Substream(io.BytesIO(b"0123456789"), start=0, length=-3)