pycharm中python测试一直‘Instantiating tests...’转圈

def get_formatted_name(first, last):
    """生成简洁的姓名"""
    full_name = first + " " + last
    return full_name.title()

import unittest
from name_function import get_formatted_name


class NamesTestCase(unittest.TestCase):
    """测试name_function.py"""

    def test_first_last_name(self):  # 必须test打头
        """能够正确处理像Janis Joplin这样的姓名吗？"""
        formatted_name = get_formatted_name('janis', 'joplin')
        self.assertEqual(formatted_name, 'Janis Joplin')


unittest.main()  # .main()告诉python运行这个文件中的测试