def test_deferred_exception_catch():
def dummy_errback(deferred_exception):
deferred_exception.catch(OSError)
return "caught"
deferred = Deferred()
deferred.add_errback(dummy_errback)
deferred.errback(OSError())
assert deferred.result == 'caught'
def test_errback():
holder = []
d = Deferred()
e = Exception('errback test')
d.add_errback(lambda e: holder.append(e))
d.errback(e)
assert isinstance(holder[0], DeferredException)
assert holder[0].value == e
def test_deferred_exception_catch():
def dummy_errback(deferred_exception):
deferred_exception.catch(OSError)
return "caught"
deferred = Deferred()
deferred.add_errback(dummy_errback)
deferred.errback(OSError())
assert deferred.result == 'caught'
def test_errback():
holder = []
d = Deferred()
e = Exception('errback test')
d.add_errback(lambda e: holder.append(e))
d.errback(e)
assert isinstance(holder[0], DeferredException)
assert holder[0].value == e
def test_errback_chain():
holder = []
d = Deferred()
e = Exception('a')
d.add_callbacks(holder.append, lambda e: Exception(e.value.args[0] + 'b'))
d.add_callbacks(holder.append, lambda e: Exception(e.value.args[0] + 'c'))
d.errback(e)
assert d.result.value.args[0] == 'abc'
assert len(holder) == 0
def test_errback_chain():
holder = []
d = Deferred()
e = Exception('a')
d.add_callbacks(holder.append, lambda e: Exception(e.value.args[0] + 'b'))
d.add_callbacks(holder.append, lambda e: Exception(e.value.args[0] + 'c'))
d.errback(e)
assert d.result.value.args[0] == 'abc'
assert len(holder) == 0
def test_callback_resolution_weaving_2():
d = Deferred()
d.add_callbacks(lambda r: fail(Exception(r + "b")), lambda e: e.value.args[0] + 'w')
d.add_callbacks(lambda e: Exception(e + "x"), lambda e: e.value.args[0] + "c")
d.add_callbacks(lambda r: Exception(r + "d"), lambda e: e.value.args[0] + 'y')
d.add_callbacks(lambda r: fail(ValueError(r + "z")), lambda e: e.value.args[0] + 'e')
d.errback(Exception('v'))
assert isinstance(d.result, DeferredException)
assert isinstance(d.result.value, ValueError)
assert d.result.value.args[0] == "vwxyz"
def test_callback_resolution_weaving_2():
d = Deferred()
d.add_callbacks(lambda r: fail(Exception(r + "b")),
lambda e: e.value.args[0] + 'w')
d.add_callbacks(lambda e: Exception(e + "x"),
lambda e: e.value.args[0] + "c")
d.add_callbacks(lambda r: Exception(r + "d"),
lambda e: e.value.args[0] + 'y')
d.add_callbacks(lambda r: fail(ValueError(r + "z")),
lambda e: e.value.args[0] + 'e')
d.errback(Exception('v'))
assert isinstance(d.result, DeferredException)
assert isinstance(d.result.value, ValueError)
assert d.result.value.args[0] == "vwxyz"
def test_deferred_list_fails():
d1 = Deferred()
d2 = Deferred()
d3 = Deferred()
dl = DeferredList([1, succeed(2), d1, d2, d3])
assert not dl.called
e1 = Exception('d1 failed')
d1.errback(e1)
d2.errback(Exception('d2 failed'))
d3.callback('hello')
assert dl.called
assert isinstance(dl.result, DeferredException)
assert dl.result.value == e1
def test_deferred_list_fails():
d1 = Deferred()
d2 = Deferred()
d3 = Deferred()
dl = DeferredList([
1,
succeed(2),
d1,
d2,
d3
])
assert not dl.called
e1 = Exception('d1 failed')
d1.errback(e1)
d2.errback(Exception('d2 failed'))
d3.callback('hello')
assert dl.called
assert isinstance(dl.result, DeferredException)
assert dl.result.value == e1
def test_cant_errback_twice():
d1 = Deferred()
d1.errback(Exception('hello'))
with raises(AlreadyCalledDeferred):
d1.errback(Exception('world'))
def test_cant_errback_twice():
d1 = Deferred()
d1.errback(Exception('hello'))
with raises(AlreadyCalledDeferred):
d1.errback(Exception('world'))
