"""cache.py DTO 单元测试。

覆盖 ``LockToken`` 的字段赋值、默认值、不可变语义与 ``__post_init__``
校验逻辑。
"""

from __future__ import annotations

import dataclasses
from datetime import datetime

import pytest
from yuxi.channels.contract.dtos.cache import LockToken
from yuxi.channels.contract.errors import ValidationError

pytestmark = pytest.mark.unit


@pytest.mark.unit
class TestLockToken:
    """锁令牌 DTO 测试。"""

    def test_fields_are_assigned(self):
        # Arrange
        now = datetime(2026, 1, 1, 12, 0, 0)
        # Act
        token = LockToken(key="lock:abc", value="token-123", expires_at=now)
        # Assert
        assert token.key == "lock:abc"
        assert token.value == "token-123"
        assert token.expires_at is now

    def test_is_frozen(self):
        # Arrange
        now = datetime(2026, 1, 1, 12, 0, 0)
        token = LockToken(key="lock:abc", value="token-123", expires_at=now)
        # Act / Assert
        with pytest.raises(dataclasses.FrozenInstanceError):
            token.key = "other"  # type: ignore[misc]

    def test_empty_key_raises_validation_error(self):
        # Arrange
        now = datetime(2026, 1, 1, 12, 0, 0)
        # Act / Assert - key 为空字符串应抛出 ValidationError
        with pytest.raises(ValidationError) as exc_info:
            LockToken(key="", value="token-123", expires_at=now)
        assert exc_info.value.field == "key"

    def test_empty_value_raises_validation_error(self):
        # Arrange
        now = datetime(2026, 1, 1, 12, 0, 0)
        # Act / Assert - value 为空字符串应抛出 ValidationError
        with pytest.raises(ValidationError) as exc_info:
            LockToken(key="lock:abc", value="", expires_at=now)
        assert exc_info.value.field == "value"