无法在Pycharm中调试单元测试

我在pycharm中调试单元测试时遇到问题。我可以通过配置很好地运行它们,但当我运行调试器时,会得到以下错误输出:

Error
Traceback (most recent call last):
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/case.py", line 59, in testPartExecutor
    yield
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/case.py", line 605, in run
    testMethod()
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/loader.py", line 34, in testFailure
    raise self._exception
ImportError: Failed to import test module: tests
Traceback (most recent call last):
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/loader.py", line 462, in _find_test_path
    package = self._get_module_from_name(name)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/loader.py", line 369, in _get_module_from_name
    __import__(name)
  File "/Users/paymahn/solvvy/scheduler/tests/__init__.py", line 2, in 
    import tests.test_setup_script
  File "/Users/paymahn/solvvy/scheduler/tests/test_setup_script.py", line 3, in 
    import setup
  File "/Applications/PyCharm.app/Contents/helpers/pydev/setup.py", line 87, in 
    data_files.append(('pydevd_attach_to_process', [os.path.join('pydevd_attach_to_process', f) for f in os.listdir('pydevd_attach_to_process') if accept_file(f)]))
FileNotFoundError: [Errno 2] No such file or directory: 'pydevd_attach_to_process'

我的目录结构是:

我的unittest配置为:

tests/test_setup_script.py 看起来像:

import unittest
import os
import setup # the path to this file is scheduler/setup.py. This import may be breaking things


class TestSetupScript(unittest.TestCase):


    def test_load_db_connection_valid_yaml_file(self):
        file_name = "valid-yaml.yml"
        with open(file_name, 'w') as file:
            file.write("""
            test:
                hello world
                a = b
                """)

        yaml = setup.load_yaml_configuration(file_name)
        # I want to debug the line above, hence no assertions here

什么是 pydevd_attach_to_process 如何确保在调试期间找到它?问题是否与正在查找的文件/目录无关?