Let me start off by saying I know this issue has already been discussed, but I could not find a solution that was similar to my case.
I have a directory structure like the following:

project/


tools  


my_tool


tool_name.py


tests


lib


constants.py
my_test.py
common/


check_lib.py





I need to import constants.py, check_lib.py, and tool_name.py into my_test.py using relative paths. Is there a way to do this even though several of my modules are in various depths within different directories in my project? I am trying to do this directly in the code with a "from module.path import module" type of import. Any help is greatly appreciated!
MY solution was the following:
tool_name.py

print("tool_name.py imported")

constants.py

print("constants.py imported")

check_lib.py

print("check_lib.py imported") 

my_test.py

import constants
  import common.check_lib  
import sys
  import os
  sys.path.append(os.path.abspath('test_project/tools/my_tool'))  
import tool_name  

output :  

constants.py imported
  check_lib.py imported
  tool_name.py imported
  my_test.py is running
Using PYTHONPATH=., go to the directory one level up from "project".
Invoke your code with somewhat long names, e.g. $ python -m project.tools.my_tool.tool_name.
That way "tools" code will be allowed to access "tests", since it's still within "project".
Import module using relative paths