def test_instance_exception():
some_rw = InstanceDouble('tchannel.rw.ReadWriter')
c_rw = rw.instance(ClassWithArgs, ('x', some_rw), ('y', rw.number(4)))
allow(some_rw).read.and_raise(ReadError("great sadness"))
with pytest.raises(ReadError):
c_rw.read(bio([1, 2, 3, 4]))
def test_instance_ignore():
c_rw = rw.instance(
ClassWithArgs,
('x', rw.number(1)),
(rw.skip, rw.constant(rw.number(2), 42)),
('y', rw.number(1)),
)
assert c_rw.read(bio([1, 2, 3, 4])) == ClassWithArgs(1, 4)
assert c_rw.write(
ClassWithArgs(1, 2), BytesIO()
).getvalue() == bytearray([1, 0, 42, 2])
def test_instance(obj, width, params, bs):
i_rw = rw.instance(*params)
assert i_rw.read(bio(bs)) == obj
assert i_rw.write(obj, BytesIO()).getvalue() == bytearray(bs)
assert i_rw.width() == width