"""全局异常处理器单元测试。

重点验证校验错误的文案压缩逻辑：FastAPI 默认返回 422 与 detail 数组，
本项目需映射为 400 与单行中文提示。
"""

from fastapi.exceptions import RequestValidationError

from app.core.constants import CODE_BAD_REQUEST
from app.core.exception_handlers import _build_response, _format_validation_errors


class TestFormatValidationErrors:
    """校验错误文案压缩。"""

    def test_包含字段名与原始说明(self) -> None:
        exc = RequestValidationError(
            [{"loc": ("body", "username"), "msg": "Field required", "type": "missing"}]
        )
        assert _format_validation_errors(exc) == "参数错误：username Field required"

    def test_去掉来源前缀只保留字段路径(self) -> None:
        exc = RequestValidationError(
            [
                {
                    "loc": ("query", "pageNum"),
                    "msg": "Input should be greater than 0",
                    "type": "greater_than",
                }
            ]
        )
        assert "query" not in _format_validation_errors(exc)
        assert "pageNum" in _format_validation_errors(exc)

    def test_多个错误时只取第一条(self) -> None:
        exc = RequestValidationError(
            [
                {"loc": ("body", "a"), "msg": "错误甲", "type": "missing"},
                {"loc": ("body", "b"), "msg": "错误乙", "type": "missing"},
            ]
        )
        message = _format_validation_errors(exc)
        assert "错误甲" in message
        assert "错误乙" not in message

    def test_错误列表为空时兜底(self) -> None:
        assert _format_validation_errors(RequestValidationError([])) == "参数错误"


class TestBuildResponse:
    """统一响应构造：HTTP 状态码与响应体 code 必须一致。"""

    def test_状态码与响应体code一致(self) -> None:
        response = _build_response(CODE_BAD_REQUEST, "参数错误")
        assert response.status_code == CODE_BAD_REQUEST
        import json

        body = json.loads(response.body)
        assert body["code"] == CODE_BAD_REQUEST
        assert body["message"] == "参数错误"
        assert body["data"] is None