I am using pycharm at one of my university projects and I wanted to integrated it with unittest module, but I have a problem with structuring my project

Part of this project involves generating abstract syntax trees, so I created AST directory and put __init__.py there, then I created expression module. I wanted to put my tests in test/ subdirectory, so it would look like this:

AST/
  __init__.py
  expression.py
  test/
      some_test.py
  utils.py

now I have also module in my AST called symbol_table and module called utils, example test class looks like

import unittest
from ...AST import expression
from ...AST import utils


class ConstantExpressionTest(unittest.TestCase):

    def testConstantExpressionCheck(self):
        constantExpression = expression.ConstantExpression(17, 5, utils.TYPES.INT)
        self.assertTrue(constantExpression.check())

when I right click on this file and select Run Unittest in ... I am getting errors:

/usr/bin/python2.7 /home/xubuntu/Downloads/pycharm-2.7.2/helpers/pycharm/utrunner.py /home/xubuntu/Przedmioty/VI/kompilatory/tk-projekt/src/AST/test/test_constant_expression.py true
Testing started at 12:06 PM ...
Traceback (most recent call last):
  File "/home/xubuntu/Downloads/pycharm-2.7.2/helpers/pycharm/utrunner.py", line 110, in <module>
    modules = [loadSource(a[0])]
  File "/home/xubuntu/Downloads/pycharm-2.7.2/helpers/pycharm/utrunner.py", line 34, in loadSource
    module = imp.load_source(moduleName, fileName)
  File "/home/xubuntu/Przedmioty/VI/kompilatory/tk-projekt/src/AST/test/test_constant_expression.py", line 2, in <module>
    from ...AST import utils
ValueError: Attempted relative import in non-package

Process finished with exit code 1

I have read about this problem and if I u

python unit-testing pycharm
Edit
Report