Sending E-Mail Unit Testing

I have written a function to send e-mail in Django. I have a written a unit test code in which i am over-riding the mail backend to in-memory django.core.mail.backends.locmem.EmailBackend.

Not working when adding decorator:

@background(schedule=datetime.datetime.now())
def send_email_to_user(recipient_email, unique_code):
    subject, from_email, to = 'Welcome', settings.DEFAULT_FROM_EMAIL, recipient_email
    html_content = render_to_string('user/email/signup_link.html', {'code': unique_code})
    text_content = strip_tags(html_content)
    msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
    msg.attach_alternative(html_content, "text/html")
    msg.send()
    return True

And without decorator working fine in unit test.

def send_email_to_user(recipient_email, unique_code):
    subject, from_email, to = 'Welcome', settings.DEFAULT_FROM_EMAIL, recipient_email
    html_content = render_to_string('user/email/signup_link.html', {'code': unique_code})
    text_content = strip_tags(html_content)
    msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
    msg.attach_alternative(html_content, "text/html")
    msg.send()
    return True

[mukulmantosh]

@philippeowagner The Task runner is not executing from test database.

[mukulmantosh]

@philippeowagner already done its not working process_tasks not picking from test db.