def test_login_logout(self):
        rv = self.login(flaskr.app.config['USERNAME'],
                        flaskr.app.config['PASSWORD'])
        assert 'You were logged in' in rv.data
        rv = self.logout()
        assert 'You were logged out' in rv.data
        rv = self.login(flaskr.app.config['USERNAME'] + 'x',
                        flaskr.app.config['PASSWORD'])
        assert 'Invalid username' in rv.data
        rv = self.login(flaskr.app.config['USERNAME'],
                        flaskr.app.config['PASSWORD'] + 'x')
        assert 'Invalid password' in rv.data
Return the dictionary mapping r to Nr, the number of samples with frequency r, where Nr > 0.
dataset/ETHPy150Open dag/flask-genshi/examples/flaskr/flaskr_tests.py/FlaskrTestCase.test_login_logout--crossover with--dataset/ETHPy150Open nltk/nltk/nltk/probability.py/FreqDist.r_Nr