create_user: Extract get_create_user_params.

We set nocoverage for the new function. Ideally it'd eventually get an
automated test, but we don't want to block this helpful refactoring on
doing so.

zerver/management/commands/create_user.py

@@ -1,15 +1,10 @@
 import argparse
-import logging
-from typing import Any, Optional
+from typing import Any
 
-from django.conf import settings
-from django.core import validators
-from django.core.exceptions import ValidationError
 from django.core.management.base import CommandError
 from django.db.utils import IntegrityError
 
 from zerver.lib.actions import do_create_user
-from zerver.lib.initial_password import initial_password
 from zerver.lib.management import ZulipBaseCommand
 
 
@@ -31,48 +26,14 @@ Omit both <email> and <full name> for interactive user creation.
         realm = self.get_realm(options)
         assert realm is not None  # Should be ensured by parser
 
-        if "email" not in options:
-            email = input("Email: ")
-        else:
-            email = options["email"]
-
-        try:
-            validators.validate_email(email)
-        except ValidationError:
-            raise CommandError("Invalid email address.")
-
-        if "full_name" not in options:
-            full_name = input("Full name: ")
-        else:
-            full_name = options["full_name"]
-
-        if options["password_file"] is not None:
-            with open(options["password_file"]) as f:
-                password: Optional[str] = f.read().strip()
-        elif options["password"] is not None:
-            logging.warning(
-                "Passing password on the command line is insecure; prefer --password-file."
-            )
-            password = options["password"]
-        else:
-            # initial_password will return a random password that
-            # is a salted hash of the email address in a
-            # development environment, and None in a production
-            # environment.
-            user_initial_password = initial_password(email)
-            if user_initial_password is None:
-                logging.info("User will be created with a disabled password.")
-            else:
-                assert settings.DEVELOPMENT
-                logging.info("Password will be available via `./manage.py print_initial_password`.")
-            password = user_initial_password
+        create_user_params = self.get_create_user_params(options)
 
         try:
             do_create_user(
-                email,
-                password,
+                create_user_params.email,
+                create_user_params.password,
                 realm,
-                full_name,
+                create_user_params.full_name,
                 # Explicitly set tos_version=None. For servers that
                 # have configured Terms of Service, this means that
                 # users created via this mechanism will be prompted to