Update the system path in a Python script to find "local" files within a project. This is especially helpful for unit testing.

sys_path_append.py

"""
Given the following directory structure: 

project-name
  docs
  scripts
  src
    lib
  test
    input
    output
    unit

Where the current file resides in 'test/unit'...
"""

# Get the relevant paths of the modules and tests. 
CURR_PATH = os.path.dirname(__file__)
MODULE_PATH = os.path.normpath(os.path.join(CURR_PATH, '../../src/'))
OUTPUT_PATH = os.path.normpath(os.path.join(CURR_PATH, '../output'))
INPUT_PATH = os.path.normpath(os.path.join(CURR_PATH, '../input'))

# Update the system path so we can find the modules we want to test. 
sys.path.append(MODULE_PATH)