"""
测试字符串工具。
无外部依赖，可离线运行。
"""

import datetime
from paste.util import ustr


class TestUstr:
    """字符串工具测试"""

    def test_str_q_count_all_cn(self):
        """全中文统计"""
        assert ustr.str_q_count("中国汉字") == 4

    def test_str_q_count_mixed(self):
        """中英文混合统计"""
        count = ustr.str_q_count("Hello中国")
        assert count == 2  # 只有中文字符算

    def test_str_q_count_empty(self):
        """空字符串统计"""
        assert ustr.str_q_count("") == 0

    def test_str_q_count_no_cn(self):
        """纯英文统计"""
        assert ustr.str_q_count("HelloWorld") == 0

    def test_to_datetime_standard(self):
        """标准格式解析"""
        result = ustr.to_datetime("2024-01-15 10:30:00", ["%Y-%m-%d %H:%M:%S"])
        assert result is not None
        assert isinstance(result, datetime.datetime)

    def test_to_datetime_invalid(self):
        """无效格式解析"""
        result = ustr.to_datetime("not-a-date", ["%Y-%m-%d"])
        assert result is None

    def test_to_datetime_empty(self):
        """空字符串解析"""
        result = ustr.to_datetime("", ["%Y-%m-%d"])
        assert result is None