settings: Add live update code for realm-level defaults settings.

This commit adds code for live-updating the realm-level default
settings page which contains only display settings as of now.

This commit also adds realm_user_settings_defaults object to
zpage_params so that we can write the tests.

frontend_tests/node_tests/dispatch.js

@@ -7,7 +7,11 @@ const {make_stub} = require("../zjsunit/stub");
 const {run_test} = require("../zjsunit/test");
 const blueslip = require("../zjsunit/zblueslip");
 const $ = require("../zjsunit/zjquery");
-const {page_params, user_settings} = require("../zjsunit/zpage_params");
+const {
+    page_params,
+    realm_user_settings_defaults,
+    user_settings,
+} = require("../zjsunit/zpage_params");
 
 const noop = () => {};
 
@@ -985,3 +989,16 @@ run_test("server_event_dispatch_op_errors", ({override}) => {
     blueslip.expect("error", "Unexpected event type user_group/other");
     server_events_dispatch.dispatch_normal_event({type: "user_group", op: "other"});
 });
+
+run_test("realm_user_settings_defaults", ({override}) => {
+    override(settings_display, "update_page", noop);
+    const event = event_fixtures.realm_user_settings_defaults__emojiset;
+    realm_user_settings_defaults.emojiset = "text";
+    let called = false;
+    settings_display.report_emojiset_change = () => {
+        called = true;
+    };
+    dispatch(event);
+    assert_same(realm_user_settings_defaults.emojiset, "google");
+    assert_same(called, true);
+});

frontend_tests/node_tests/lib/events.js

@@ -518,6 +518,13 @@ exports.fixtures = {
         },
     },
 
+    realm_user_settings_defaults__emojiset: {
+        type: "realm_user_settings_defaults",
+        op: "update",
+        property: "emojiset",
+        value: "google",
+    },
+
     restart: {
         type: "restart",
         zulip_version: "4.0-dev+git",

frontend_tests/zjsunit/index.js

@@ -102,6 +102,8 @@ try {
         require("../../static/js/page_params");
         namespace.mock_esm("../../static/js/user_settings", zpage_params);
         require("../../static/js/user_settings");
+        namespace.mock_esm("../../static/js/realm_user_settings_defaults", zpage_params);
+        require("../../static/js/realm_user_settings_defaults");
 
         run_one_module(file);
 

frontend_tests/zjsunit/zpage_params.js

@@ -1,6 +1,7 @@
 "use strict";
 
 exports.page_params = {};
+exports.realm_user_settings_defaults = {};
 exports.user_settings = {};
 
 exports.reset = () => {
@@ -14,4 +15,9 @@ exports.reset = () => {
             delete exports.user_settings[field];
         }
     }
+    for (const field in exports.realm_user_settings_defaults) {
+        if (Object.prototype.hasOwnProperty.call(exports.realm_user_settings_defaults, field)) {
+            delete exports.realm_user_settings_defaults[field];
+        }
+    }
 };

static/js/server_events_dispatch.js

@@ -36,6 +36,7 @@ import * as reactions from "./reactions";
 import * as realm_icon from "./realm_icon";
 import * as realm_logo from "./realm_logo";
 import * as realm_playground from "./realm_playground";
+import {realm_user_settings_defaults} from "./realm_user_settings_defaults";
 import * as reload from "./reload";
 import * as scroll_bar from "./scroll_bar";
 import * as settings_account from "./settings_account";
@@ -381,6 +382,36 @@ export function dispatch_normal_event(event) {
             }
             break;
 
+        case "realm_user_settings_defaults": {
+            realm_user_settings_defaults[event.property] = event.value;
+
+            const display_settings_list = [
+                "color_scheme",
+                "default_view",
+                "demote_inactive_streams",
+                "dense_mode",
+                "emojiset",
+                "fluid_layout_width",
+                "high_contrast_mode",
+                "left_side_userlist",
+                "translate_emoticons",
+                "starred_message_counts",
+            ];
+
+            const container_elem = $("#realm-user-default-settings");
+            if (display_settings_list.includes(event.property)) {
+                settings_display.update_page(container_elem, realm_user_settings_defaults);
+            }
+
+            if (event.property === "emojiset") {
+                settings_display.report_emojiset_change(
+                    container_elem,
+                    realm_user_settings_defaults,
+                );
+            }
+            break;
+        }
+
         case "realm_user":
             switch (event.op) {
                 case "add":