def test_Error_unwrap_does_not_create_reference_cycles():
# See comment in Error.unwrap for why reference cycles are tricky
exc = ValueError()
err = Error(exc)
try:
err.unwrap()
except ValueError:
pass
# Top frame in the traceback is the current test function; we don't care
# about its references
assert exc.__traceback__.tb_frame is sys._getframe()
# The next frame down is the 'unwrap' frame; we want to make sure it
# doesn't reference the exception (or anything else for that matter, just
# to be thorough)
unwrap_frame = exc.__traceback__.tb_next.tb_frame
assert unwrap_frame.f_code.co_name == "unwrap"
assert unwrap_frame.f_locals == {}
def test_Outcome():
v = Value(1)
assert v.value == 1
assert v.unwrap() == 1
assert repr(v) == "Value(1)"
with pytest.raises(AlreadyUsedError):
v.unwrap()
v = Value(1)
exc = RuntimeError("oops")
e = Error(exc)
assert e.error is exc
with pytest.raises(RuntimeError):
e.unwrap()
with pytest.raises(AlreadyUsedError):
e.unwrap()
assert repr(e) == f"Error({exc!r})"
e = Error(exc)
with pytest.raises(TypeError):
Error("hello")
with pytest.raises(TypeError):
Error(RuntimeError)
def expect_1():
assert (yield) == 1
yield "ok"
it = iter(expect_1())
next(it)
assert v.send(it) == "ok"
with pytest.raises(AlreadyUsedError):
v.send(it)
def expect_RuntimeError():
with pytest.raises(RuntimeError):
yield
yield "ok"
it = iter(expect_RuntimeError())
next(it)
assert e.send(it) == "ok"
with pytest.raises(AlreadyUsedError):
e.send(it)
class Future:
"""A very simple Future for trio based on `trio.Event`."""
def __init__(self):
self._outcome = None
self._event = trio.Event()
def set_result(self, result):
self._outcome = Value(result)
self._event.set()
def set_exception(self, exc):
self._outcome = Error(exc)
self._event.set()
async def get(self):
await self._event.wait()
return self._outcome.unwrap()