144acbea7a
Motivation: A server sends data packages that consist of multiple serialized capnproto messages of different structures. Every message is guaranteed to have the same first field, which works as a message header containing information about the message structure type. The scheme comprises the `UnknownMessage` structure that allows parsing the header only. Solution: provide a public interface that iterates buffer with AnyPointer readers to cast a message to `UnknownMessage` first and then to a specific structure type.
94 lines
2.2 KiB
Python
94 lines
2.2 KiB
Python
import os
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import pytest
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import capnp
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this_dir = os.path.dirname(__file__)
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@pytest.fixture
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def message_schemas():
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return capnp.load(os.path.join(this_dir, "test_structs_sequence.capnp"))
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@pytest.fixture
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def make_apple(message_schemas):
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def _make_apple(color: str):
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apple = message_schemas.Apple.new_message()
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apple.fruitId = message_schemas.FruitId.apple
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apple.color = color
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return apple
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return _make_apple
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@pytest.fixture
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def red_apple(make_apple):
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return make_apple("Red")
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@pytest.fixture
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def green_apple(make_apple):
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return make_apple("Green")
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@pytest.fixture
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def banana(message_schemas):
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banana_ = message_schemas.Banana.new_message()
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banana_.fruitId = message_schemas.FruitId.banana
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banana_.length = 12.345
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return banana_
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@pytest.fixture
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def cherry(message_schemas):
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cherry_ = message_schemas.Cherry.new_message()
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cherry_.fruitId = message_schemas.FruitId.cherry
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cherry_.sweetness = 64
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return cherry_
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@pytest.fixture
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def fruit_basket(cherry, red_apple, banana, green_apple):
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return [cherry, red_apple, banana, green_apple]
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@pytest.fixture
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def fruit_basket_encoded(fruit_basket):
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return b"".join(fruit.to_bytes_packed() for fruit in fruit_basket)
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@pytest.fixture
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def expected(fruit_basket):
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return [fruit.to_dict() for fruit in fruit_basket]
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def test_parse_structs_sequence(message_schemas, fruit_basket_encoded, expected):
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# ARRANGE
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reader = capnp.read_multiple_bytes_packed(fruit_basket_encoded)
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def _parse_fruit(any_):
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unknown_fruit = any_.as_struct(message_schemas.UnknownFruit)
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if unknown_fruit.fruitId == message_schemas.FruitId.apple:
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return any_.as_struct(message_schemas.Apple)
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if unknown_fruit.fruitId == message_schemas.FruitId.banana:
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return any_.as_struct(message_schemas.Banana)
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if unknown_fruit.fruitId == message_schemas.FruitId.cherry:
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return any_.as_struct(message_schemas.Cherry)
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return unknown_fruit
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# ACT
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parsed = [_parse_fruit(any_).to_dict() for any_ in reader]
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# ASSERT
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assert parsed == expected
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def test_empty_sequence():
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reader = capnp.read_multiple_bytes_packed(b"")
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assert len(list(reader)) == 0
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