Run Nosestests on the tests folder and get coverage just for files in the src folder

Question

My project has the following structure:

Project
    ├── __init__.py
    ├── __main__.py
    ├── test
    │   ├── __init__.py
    │   ├── my_mocker.py
    │   ├── test_first_module.py
    │   ├── test_second_module.py
    │   ├── ...
    │   └── test_nth_module.py
    └── src
        ├── first_module.py
        ├── second_module.py
        ├── ...
        └── nth_module.py

I want to run nosetests on the tests in the tests directory. The tests have all the filename structure test_* and I want to use --with-coverage but only get the result on the files in the src folder.
All tests are written with unittest.
Can somebody help me to say how the command line of nonetests should look like. I have checked everything without success. I am getting in the coverage also all site-packages files.