There is problem with import of module from parent directory as __main__ lies in child folder
if you do the folder structure like below your same code for import will work

+----test
     +---test_models.py
     +---__init__.py
     +---address_book
         +---__init__.py
         +---models.py

There is problem with import of module from parent directory as __main__ lies in child folder
if you do the folder structure like below your same code for import will work

+----test
     +---test_models.py
     +---__init__.py
     +---address_book
         +---__init__.py
         +---models.py

or you can add your project path to PYTHONPATH variable and your same code will work