How to setup web2py enviroment for unittest

I have the following directory structure:

web2py/applications/myapp
web2py/applications/myapp/controllers/account.py
web2py/applications/myapp/models/db.py
web2py/applications/myapp/tests/runner.py
web2py/applications/myapp/tests/test_account.py

In account.py, there is a function accessing models/db.py, for instance

def calcExpense():
    rows = db(db.expense.id >0).select()
    expense = blah and blah..
    return expense

In test_account.py, I would like to test calcExpense:

class TestAccount(unittest.TestCase):
    def testCalcExpense(self):
        self.assertTrue()
suite = unittest.TestSuite()
suite.addTest(unittest.makeSuite(TestAccount))
unittest.TextTestRunner(verbosity=2).run(suite)

If I run under web2py directory with python web2py.py -S myapp -M -R applications/myapp/tests/test_account.py, everything is fine thanks web2py setting all required environment.

But I don't want to run unittest one way for web2py (under web2py directory), and another way for the all other python projects (under tests).

In particular, I want to run all tests through the test runner, under tests by:

`python -m unittest -v runner`

How can I setup the enviroment in runner.py, so that test_account.py can import account.py, account.py have access to both db.py and tables defined in db.py?