def test_constant_w(other, v1, v2):
# constant(f, x).write(s, *) == f.write(x, *)
assert other.write(
v1, BytesIO()
).getvalue() == rw.constant(other, v1).write(
v2, BytesIO()
).getvalue()
def test_dictionary_ignore_fields():
d_rw = rw.dictionary(
('x', rw.number(1)),
(rw.skip, rw.constant(rw.number(2), 42)),
)
assert d_rw.read(bio([1, 0, 2])) == {'x': 1}
assert d_rw.write(
{'x': 1, rw.skip: 2, 'y': 3}, BytesIO()
).getvalue() == bytearray([1, 0, 42])
assert d_rw.width() == 3
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_constant_r(other, bs):
stream = bio(bs)
assert rw.constant(other, 42).read(stream) == 42
assert stream.read() == ''
assert rw.constant(other, 42).width() == other.width()
