Extract zerver/lib/events.py from actions.py with event registration.

This moves do_events_register, fetch_initial_state_data and friends to
a new file.

Modified significantly by tabbott for correctness and to remove unused
imports.

Fixes zulip#3635.

docs/events-system.md

@@ -196,7 +196,8 @@ dozens of queries to the database, caches, etc. over the course of
 things together atomically.  So instead, we use a more complicated
 algorithm that can produce the atomic result from non-atomic
 subroutines.  Here's how it works when you make a `register` API
-request.  The request is directly handled by Django:
+request; the logic is in `zerver/views/events_register.py` and
+`zerver/lib/events.py`.  The request is directly handled by Django:
 
 * Django makes an HTTP request to Tornado, requesting that a new event
   queue be created, and records its queue ID.

docs/new-feature-tutorial.md

@@ -181,7 +181,7 @@ realm. :
 ### Update application state
 
 You then need to add code that will handle the event and update the
-application state. In `zerver/lib/actions.py` update the
+application state. In `zerver/lib/events.py` update the
 `fetch_initial_state` and `apply_events` functions. :
 
     def fetch_initial_state_data(user_profile, event_types, queue_id):

zerver/tests/test_events.py

@@ -12,7 +12,6 @@
 )
 
 from zerver.lib.actions import (
-    apply_events,
     bulk_remove_subscriptions,
     do_add_alert_words,
     check_add_realm_emoji,
@@ -59,9 +58,11 @@
     do_change_enable_digest_emails,
     do_add_realm_alias,
     do_remove_realm_alias,
+)
+from zerver.lib.events import (
+    apply_events,
     fetch_initial_state_data,
 )
-
 from zerver.lib.message import render_markdown
 from zerver.lib.test_helpers import POSTRequestMock, get_subscription
 from zerver.lib.test_classes import (

zerver/tests/tests.py

@@ -1969,8 +1969,8 @@ def test_home(self):
     def _get_home_page(self, **kwargs):
         # type: (**Any) -> HttpResponse
         with \
-                patch('zerver.lib.actions.request_event_queue', return_value=42), \
-                patch('zerver.lib.actions.get_user_events', return_value=[]):
+                patch('zerver.lib.events.request_event_queue', return_value=42), \
+                patch('zerver.lib.events.get_user_events', return_value=[]):
             result = self.client_get('/', dict(**kwargs))
         return result
 

zerver/views/events_register.py

@@ -4,7 +4,7 @@
 from typing import Text
 from typing import Iterable, Optional, Sequence
 
-from zerver.lib.actions import do_events_register
+from zerver.lib.events import do_events_register
 from zerver.lib.request import REQ, has_request_variables
 from zerver.lib.response import json_success
 from zerver.lib.validator import check_string, check_list, check_bool

zerver/views/home.py

@@ -18,8 +18,9 @@
     PreregistrationUser, get_client, UserActivity, \
     UserPresence, get_recipient, name_changes_disabled, email_to_username, \
     list_of_domains_for_realm
+from zerver.lib.events import do_events_register
 from zerver.lib.actions import update_user_presence, do_change_tos_version, \
-    do_events_register, do_update_pointer, get_cross_realm_dicts, realm_user_count
+    do_update_pointer, get_cross_realm_dicts, realm_user_count
 from zerver.lib.avatar import avatar_url
 from zerver.lib.i18n import get_language_list, get_language_name, \
     get_language_list_for_templates

zerver/views/registration.py

@@ -17,9 +17,10 @@
     name_changes_disabled, email_to_username, \
     completely_open, get_unique_open_realm, email_allowed_for_realm, \
     get_realm, get_realm_by_email_domain
+from zerver.lib.events import do_events_register
 from zerver.lib.actions import do_change_password, do_change_full_name, do_change_is_admin, \
     do_activate_user, do_create_user, do_create_realm, set_default_streams, \
-    do_events_register, user_email_is_unique, \
+    user_email_is_unique, \
     compute_mit_user_fullname
 from zerver.forms import RegistrationForm, HomepageForm, RealmCreationForm, \
     CreateUserForm, FindMyTeamForm