Откат транзакций не работает с py.тест и фляга

Я использую py.тест для тестирования моего приложения Flask, но я получаю IntegrityError, потому что я создаю ту же модель в двух разных тестах.

Я использую postgreSQL 9.3.5 и Flask-SQLAlchemy 1.0.

EDIT я обновил свое приспособление sessoin с ответом Джереми Аллена, и он исправил много ошибок. Однако кажется, когда я использую пользовательское приспособление, которое я все еще получаю IntegrityErrors

E       IntegrityError: (IntegrityError) duplicate key value violates unique constraint "ix_users_email"
E       DETAIL:  Key (email)=(not_used@example.com) already exists.
E        'INSERT INTO users (email, username, name, role_id, company_id, password_hash, confirmed, member_since, last_seen) VALUES (%(email)s, %(username)s, %(name)s, %(role_id)s, %(company_id)s, %(password_hash)s, %(confirmed)s, %(member_since)s, %(last_seen)s) RETURNING users.id' {'username': 'not_used', 'confirmed': True, 'name': 'To be Removed', 'member_since': datetime.datetime(2014, 10, 29, 19, 19, 41, 7929), 'company_id': None, 'role_id': 3, 'last_seen': datetime.datetime(2014, 10, 29, 19, 19, 41, 7941), 'email': 'not_used@example.com', 'password_hash': 'pbkdf2:sha1:1000$cXUh6GbJf38242871cff5e4cce4c1dc49a62c4aea4ba1f3'}

conftest.py

@pytest.yield_fixture(scope='session')
def app():
    app = create_app('testing')
    app.config['SERVER_NAME'] = 'example.com:1234'
    ctx = app.app_context()
    ctx.push()
    app.response_class = TestResponse
    app.test_client_class = TestClient
    yield app
    ctx.pop()


@pytest.fixture(scope='session')
def db(app):
    _db.drop_all()
    _db.create_all()

    Permission.insert_initial()
    Role.insert_initial()
    Technology.insert_initial()
    Product.insert_initial()
    Actor.insert_initial()
    Industry.insert_initial()
    DeliveryCategory.insert_initial()
    DeliveryMethod.insert_initial()

    user = User(email='admin@example.com', username='admin', confirmed=True, password='admin', name='Admin')
    user.role = Role.query.filter_by(name='Administrator').first()
    _db.session.add(user)
    _db.session.commit()

    return _db


@pytest.yield_fixture(scope='function')
def session(db):
    db.session.begin_nested()
    yield db.session
    db.session.rollback()


@pytest.yield_fixture(scope='function')
def user(session):
    yield session.query(User).filter_by(email='admin@example.com').first()


@pytest.yield_fixture(scope='function')
def client(app, user):
    client = app.test_client()
    client.auth = 'Basic ' + b64encode((user.email + ':' + 'admin').encode('utf-8')).decode('utf-8')
    yield client

тесты, которые не

def test_edit_agenda_add_company_rep_without_company(session, client, user):
    user2 = User(name='To be Removed', password='not_used', username='not_used', confirmed=True,
                email='not_used@example.com', role=Role.query.filter_by(name='User').first())
    agenda = Agenda(name='Invalid Company Rep', creator=user)
    session.add(agenda)
    session.commit()

    response = client.jput('/api/v1.0/agendas/%s' % agenda.id,
        data={
            'company_representative': user2.id
        }
    )
    assert response.status_code == 200

def test_edit_agenda_add_user_already_in_agenda(session, client, user):
    user2 = User(name='To be Removed', password='not_used', username='not_used', confirmed=True,
                email='not_used@example.com', role=Role.query.filter_by(name='User').first())
    agenda = Agenda(name='Invalid Company Rep', creator=user)
    agenda.users.append(user2)
    session.add(agenda)
    session.commit()

    response = client.jput('/api/v1.0/agendas/%s' % agenda.id,
        data={
            'users': [user2.id]
        }
    )
    assert response.status_code == 200

тесты, которые передают

def test_get_agenda_modules_where_agenda_that_does_not_exist(session, app):
    # Create admin user with permission to create models
    user = User(email='admin2@example.com', username='admin2', confirmed=True, password='admin2')
    user.role = Role.query.filter_by(name='Administrator').first()
    session.add(user)
    session.commit()

    client = app.test_client()
    client.auth = 'Basic ' + b64encode(
        (user.email + ':' + 'admin2').encode('utf-8')).decode('utf-8')
    response = client.jget('/api/v1.0/agenda-modules/%s/%s' % (5, 4))
    assert response.status_code == 404

def test_get_agenda_modules_agenda_modules_does_not_exist(session, app):
    agenda = Agenda(name='Is tired in the AM')
    session.add(agenda)

    # Create admin user with permission to create models
    user = User(email='admin2@example.com', username='admin2', confirmed=True, password='admin2')
    user.role = Role.query.filter_by(name='Administrator').first()
    session.add(user)
    session.commit()

    client = app.test_client()
    client.auth = 'Basic ' + b64encode(
        (user.email + ':' + 'admin2').encode('utf-8')).decode('utf-8')
    response = client.jget('/api/v1.0/agenda-modules/%s/%s' % (agenda.id, 4))
    assert response.status_code == 400
    assert response.jdata['message'] == 'AgendaModule does not exist.'