Python: How to generate a random phone number?

Question

Not a duplicate of Making random phone number xxx-xxx-xxxx

My project uses python-phonenumbers and django-phonenumber-field for phone number validation. Within the project are vast lists of custom validation rules, for which naive approach like this will not be sufficient:

>>> import functools
>>> import random
>>> a = functools.partial(random.randint, 0, 9)
>>> gen = lambda: "+{}-{}{}{}-{}{}{}-{}{}{}{}".format(a(), a(), a(), a(), a(), a(), a(), a(), a(), a(), a())
>>> gen()
'+2-758-702-0180'  # Obviously wrong
>>> gen()
'+1-911-555-0180'  # Obviously wrong, it has 911 in it

So, without resorting to a brute-force while loop that has no upper bound, and without introducing an upper bound for such trivial problems, what better ways are there to generate valid phone numbers accepted by the validator itself?

from phonenumber_field.validators import validate_international_phonenumber
from django.core.exceptions import ValidationError

def generate_valid_number():
    while True:  # While loops are not desired, even with an upper bound!
        try:
            number = gen()
            validate_international_phonenumber(number)
            return number
        except ValidationError:
            pass

Answer 1

If you're using the package faker you can write a custom provider that can be re-used across your project.

import phonenumbers
from faker.providers.phone_number.en_US import Provider

class CustomPhoneProvider(Provider):
    def phone_number(self):
        while True:
            phone_number = self.numerify(self.random_element(self.formats))
            parsed_number = phonenumbers.parse(phone_number, 'US')
            if phonenumbers.is_valid_number(parsed_number):
                return phonenumbers.format_number(
                    parsed_number,
                    phonenumbers.PhoneNumberFormat.E164
                )

Used with factory_boy:

import factory
from faker import Faker

from .models import User
from .providers import CustomPhoneProvider

fake = Faker()
fake.add_provider(CustomPhoneProvider)

class UserFactory(factory.DjangoModelFactory):
    class Meta:
        model = User

    first_name = factory.Faker('first_name')
    last_name = factory.Faker('last_name')
    phone_number = factory.LazyAttribute(lambda _: fake.phone_number())