refactor: Extract can_view_subscribers().

We also remove some needless uses of the calculated
field in the node tests.

frontend_tests/node_tests/compose.js

@@ -1149,7 +1149,6 @@ test_ui("needs_subscribe_warning", () => {
     const sub = {
         stream_id: 110,
         name: "stream",
-        can_access_subscribers: true,
     };
 
     stream_data.add_sub(sub);

frontend_tests/node_tests/compose_fade.js

@@ -59,7 +59,6 @@ run_test("set_focused_recipient", () => {
         stream_id: 101,
         name: "social",
         subscribed: true,
-        can_access_subscribers: true,
     };
 
     compose_fade.set_focused_recipient("stream");

frontend_tests/node_tests/composebox_typeahead.js

@@ -172,7 +172,6 @@ const sweden_stream = {
     description: "Cold, mountains and home decor.",
     stream_id: 1,
     subscribed: true,
-    can_access_subscribers: true,
 };
 const denmark_stream = {
     name: "Denmark",

frontend_tests/node_tests/peer_data.js

@@ -16,7 +16,6 @@ const {page_params} = require("../zjsunit/zpage_params");
 const peer_data = zrequire("peer_data");
 const people = zrequire("people");
 const stream_data = zrequire("stream_data");
-const stream_settings_data = zrequire("stream_settings_data");
 
 page_params.is_admin = false;
 page_params.realm_users = [];
@@ -114,7 +113,6 @@ test("subscribers", () => {
     ]);
 
     peer_data.set_subscribers(stream_id, [me.user_id, fred.user_id, george.user_id]);
-    stream_settings_data.update_calculated_fields(sub);
     assert(stream_data.is_user_subscribed(stream_id, me.user_id));
     assert(stream_data.is_user_subscribed(stream_id, fred.user_id));
     assert(stream_data.is_user_subscribed(stream_id, george.user_id));
@@ -182,7 +180,6 @@ test("subscribers", () => {
 
     // Verify that we noop and don't crash when unsubscribed.
     sub.subscribed = false;
-    stream_settings_data.update_calculated_fields(sub);
     peer_data.add_subscriber(stream_id, brutus.user_id);
     assert.equal(stream_data.is_user_subscribed(stream_id, brutus.user_id), true);
     peer_data.remove_subscriber(stream_id, brutus.user_id);
@@ -196,7 +193,6 @@ test("subscribers", () => {
         2,
     );
     sub.invite_only = true;
-    stream_settings_data.update_calculated_fields(sub);
     assert.equal(stream_data.is_user_subscribed(stream_id, brutus.user_id), undefined);
     peer_data.remove_subscriber(stream_id, brutus.user_id);
     assert.equal(stream_data.is_user_subscribed(stream_id, brutus.user_id), undefined);

frontend_tests/node_tests/stream_events.js

@@ -402,8 +402,6 @@ test("remove_deactivated_user_from_all_streams", () => {
     const subs_stub = make_stub();
     subs.update_subscribers_ui = subs_stub.f;
 
-    dev_help.can_access_subscribers = true;
-
     // assert starting state
     assert(!stream_data.is_user_subscribed(dev_help.stream_id, george.user_id));
 

static/js/stream_data.js

@@ -515,6 +515,11 @@ export function can_change_permissions(sub) {
     return page_params.is_admin && (!sub.invite_only || sub.subscribed);
 }
 
+export function can_view_subscribers(sub) {
+    // Guest users can't access subscribers of any(public or private) non-subscribed streams.
+    return page_params.is_admin || sub.subscribed || (!page_params.is_guest && !sub.invite_only);
+}
+
 export function is_subscribed(stream_name) {
     const sub = get_sub(stream_name);
     return sub !== undefined && sub.subscribed;
@@ -592,7 +597,7 @@ export function maybe_get_stream_name(stream_id) {
 
 export function is_user_subscribed(stream_id, user_id) {
     const sub = get_sub_by_id(stream_id);
-    if (sub === undefined || !sub.can_access_subscribers) {
+    if (sub === undefined || !can_view_subscribers(sub)) {
         // If we don't know about the stream, or we ourselves cannot access subscriber list,
         // so we return undefined (treated as falsy if not explicitly handled).
         blueslip.warn(

static/js/stream_settings_data.js

@@ -54,11 +54,10 @@ export function update_calculated_fields(sub) {
     sub.should_display_subscription_button = stream_data.can_toggle_subscription(sub);
     sub.should_display_preview_button = stream_data.can_preview(sub);
     sub.can_change_stream_permissions = stream_data.can_change_permissions(sub);
-    // User can add other users to stream if stream is public or user is subscribed to stream.
-    // Guest users can't access subscribers of any(public or private) non-subscribed streams.
-    sub.can_access_subscribers =
-        page_params.is_admin || sub.subscribed || (!page_params.is_guest && !sub.invite_only);
+    sub.can_access_subscribers = stream_data.can_view_subscribers(sub);
+
     sub.preview_url = hash_util.by_stream_uri(sub.stream_id);
+    // User can add other users to stream if stream is public or user is subscribed to stream.
     sub.can_add_subscribers = !page_params.is_guest && (!sub.invite_only || sub.subscribed);
     sub.is_old_stream = sub.stream_weekly_traffic !== null;
     if (sub.rendered_description !== undefined) {

static/js/stream_ui_updates.js

@@ -151,7 +151,7 @@ export function update_subscribers_list(sub) {
         return;
     }
 
-    if (!sub.can_access_subscribers) {
+    if (!stream_data.can_view_subscribers(sub)) {
         $(".subscriber_list_settings_container").hide();
     } else {
         const subscribers = peer_data.get_subscribers(sub.stream_id);