Postgres error "SAVEPOINT can only be used in transaction blocks" when used with live_server

I have tests, that I would like to run with live_server from pytest-flask package.

I thought it works ok, but only for single request. Full repo with working example, failing test

Here are some pieces of the code:

# models.py
class Category(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String, unique=True, nullable=False)

# view
@blog.route('/categories')
def list_categories():
    return '<br/>'.join(str(x.id) + ': ' + x.name for x in models.Category.query)

factories from conftest.py

@pytest.fixture(scope='function')
def base_factory(db_session):
    class BaseFactory(factory.alchemy.SQLAlchemyModelFactory):
        class Meta:
            abstract = True
            sqlalchemy_session = db_session
            sqlalchemy_session_persistence = 'flush'
    return BaseFactory

@pytest.fixture(scope='function')
def category_factory(base_factory):
    class CategoryFactory(base_factory):
        class Meta:
            model = models.Category
        name = factory.Sequence(lambda n: u'Category %d' % n)
    return CategoryFactory

Test itself:

from flask import url_for
import requests

from demo_app import models

def test_list_categories(live_server, category_factory):
    categories = category_factory.create_batch(5)

    assert models.Category.query.count() == 5

    url = url_for('blog.list_categories', _external=True)

    response_1 = requests.get(url)

    assert response_1.status_code == 200
    data_1 = response_1.content.decode('utf-8')
    for category in categories:
        assert category.name in data_1

    assert models.Category.query.count() == 5

    response_2 = requests.get(url)

    assert response_2.status_code == 200
    data_2 = response_2.content.decode('utf-8')
    print(data_2)
    for category in categories:
        assert category.name in data_2

I’m getting error on line assert models.Category.query.count() == 5, or if I comment it out, data_2 data returned by the server is empty.

The error:

self = <sqlalchemy.dialects.postgresql.psycopg2.PGDialect_psycopg2 object at 0x104135780>
cursor = <cursor object at 0x1040ea900; closed: -1>
statement = 'SAVEPOINT sa_savepoint_23', parameters = {}
context = <sqlalchemy.dialects.postgresql.psycopg2.PGExecutionContext_psycopg2 object at 0x104321048>

    def do_execute(self, cursor, statement, parameters, context=None):
>       cursor.execute(statement, parameters)
E       sqlalchemy.exc.InternalError: (psycopg2.errors.NoActiveSqlTransaction) SAVEPOINT can only be used in transaction blocks
E       
E       [SQL: SAVEPOINT sa_savepoint_23]
E       (Background on this error at: http://sqlalche.me/e/2j85)

Full stack trace

Could you please help me, I don’t know where to start to investigate this.

[jeancochrane]

Awesome, thanks @citizen-stig! I’ll have time to do some testing this weekend.

[citizen-stig]

@jeancochrane , I’ve finally managed to create docker environment, repository is updated: https://github.com/citizen-stig/flask-pytest-samples

just use docker-compose up and error will be printed in console