How to import python script using ROS and unittest - python-2.x

Question

I'm facing an issue in a ROS (Python 2.7) project.
Strucure
I'm working on a ROS project. The structure is the following:
probable-adventure
|
|-catkin_ws
|-src
|-ros_rover
|-include
|-launch
|-msg
|-__init__.py
|-Commands.msg
|-Teleoperation.msg
|-scripts
|-__init__.py
|-keyboard.py
|-test
|-__init__.py
|-testing.py
|-__init__.py
|-CMakeLists.txt
|-package.xml
Keyboard node (secondary problem)
keyboard.py starts as follows:
#!/usr/bin/env python
import rospy
from ros_rover.msg import Teleoperation
I describe it as a secondary problem because if I compile the project from catkin_ws directory using catkin_make command, everything works well and I can run the keyboard ROS node perfectly even though I get a pylint error in the from ros_rover.msg ... line.
Unable to import 'ros_rover.msg'
Main Problem
I just wrote the previous as context. The point is that I have to test the code within the scripts directory. I'm using unittest and I create python files in test directory.
I have create the following simple test (testing.py):
#!/usr/bin/env python
import unittest
from scripts.keyboard import GetKey
class TestBareBones(unittest.TestCase):
def test_one_equals_one(self):
self.assertEquals(1, 1, "1!=1")
if __name__ == '__main__':
unittest.main()
I think I have a problem with the imports because if I run the following python commands (from the ros_rover directory):
user#dubuntu:~/probable-adventure/catkin_ws/src/ros_rover$ python testing.py
user#dubuntu:~/probable-adventure/catkin_ws/src/ros_rover$ python -m testing
I get the following error:
File "/home/diego/Documents/probable-adventure/catkin_ws/src/ros_rover/test/prueba.py", line 5, in <module>
from scripts.keyboard import GetKey
File "scripts/keyboard.py", line 14, in <module>
from ros_rover.msg import Teleoperation
ImportError: No module named ros_rover.msg
My thought
I think the problem is related with imports because I have read that python imports depends on the directory from where you run the python command.
I run the test from ros_rover directory because the test's import is scripts.keyboard so it can found it (scripts is in ros_rover). But when the keyboard.py tries to import ros_rover.msg fails because I'm already in ros_rover directory and cannot find ros_rover.
I have read a lot here in StackOverflow and out of it but I didn't find a solution (I have added a empty __init__.py file to ros_rover, scripts and test directories).