def test_poll_empty():
"""
GIVEN
Channel is empty.
WHEN
Polled for an item.
EXPECT
Returns None
"""
q = asyncio.Queue()
ch = Channel(q)
assert ch.poll() is None
def test_poll_empty_given_value():
"""
GIVEN
Channel is empty.
WHEN
Polled for an item, and a default value is given.
EXPECT
Returns the given default value.
"""
q = asyncio.Queue()
ch = Channel(q)
x = 'x'
assert ch.poll(default=x) == x
def test_poll():
"""
GIVEN
Channel is not empty.
WHEN
Polled for an item.
EXPECT
Returns the item.
"""
x = 'x'
q = asyncio.Queue()
q.put_nowait(x)
ch = Channel(q)
assert ch.poll() == x
async def test_item_unblock():
"""
GIVEN
Channel is open and empty.
WHEN
Wait for item, and item is added while blocked.
EXPECT
Unblocks and returns True.
"""
q = asyncio.Queue()
ch = Channel(q)
x = 'x'
asyncio.get_running_loop().call_later(0.05, ch.offer, x)
assert await ch.item(timeout=0.1)
assert ch.poll() == x