[Feature Request] Support FakeStrictRedis for tests

[caffeinatedMike]

The current rq module suggests using fakeredis.FakeStrictRedis when running tests, but doing so with this scheduler causes an rq.connections.NoRedisConnectionException: Could not resolve a Redis connection error. Example app_factory function below:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from rq_scheduler import Scheduler
from redis import Redis
from rq import Queue

db = SQLAlchemy()

def create_app(config_obj='config.DevelopmentConfig'):
    app = Flask(__name__)
    app.config.from_object(config_obj)

    # Setup database components
    db.init_app(app)

    with app.app_context():
        from app import models
        # create db models
        db.create_all()
        # import routes and tasks
        from app import views, tasks

    # Initialize Redis components
    if app.testing:
        from fakeredis import FakeStrictRedis
        app.redis = FakeStrictRedis()
        app.task_queue = Queue('reporting-tasks', is_async=False, connection=app.redis)
    else:
        app.redis = Redis.from_url(app.config['REDIS_URL'])
        app.task_queue = Queue('reporting-tasks', connection=app.redis)

    app.scheduler = Scheduler(queue=app.task_queue)  # Scheduler fails when task_queue utilizes FakeStrictRedis
    if 'check_failed_jobs' not in app.scheduler:
        app.scheduler.cron('*/5 * * * *', func=tasks.check_failed_jobs, args=[config_obj], id='check_failed_jobs')

    return app

[caffeinatedMike]

So, after reviewing the test setup for this package I realized there was a straight-forward way to utilize fakeredis for tests. The only thing I was missing, and what was presumably leading to the the connection error was the push_connection function from rq. The below setup works when the app is in testing mode.

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_wtf import CSRFProtect
from rq_scheduler import Scheduler
from redis import Redis
from rq import Queue

db = SQLAlchemy()
csrf = CSRFProtect()

def create_app(config_obj='config.DevelopmentConfig'):
    app = Flask(__name__)
    app.config.from_object(config_obj)

    # Initialize CSRF protection
    csrf.init_app(app)

    # Setup database components
    db.init_app(app)

    with app.app_context():
        from app import models
        # create db models
        db.create_all()
        # import routes
        from app import views

    # Initialize redis components
    if app.testing:
        from fakeredis import FakeStrictRedis
        from rq import push_connection
        app.redis = FakeStrictRedis()
        push_connection(app.redis)  # <= The missing piece
        app.task_queue = Queue('reporting-tasks', is_async=False, connection=app.redis)
    else:
        app.redis = Redis.from_url(app.config['REDIS_URL'])
        app.task_queue = Queue('reporting-tasks', connection=app.redis)

    # Initialize scheduler and associated crons
    app.scheduler = Scheduler(queue=app.task_queue)
    app.scheduler.cron('*/5 * * * *', func='app.tasks:check_failed_jobs', id='check_failed_jobs')
    app.scheduler.cron('* * */1 * *', func='app.tasks:purge_old_logs', id='purge_old_logs')

    return app