roster: Only fetch from browser storage if already cached

spec/smacks.js

@@ -44,10 +44,6 @@
                 `<iq from="romeo@montague.lit/orchard" id="${iq.getAttribute('id')}" to="romeo@montague.lit" type="get" xmlns="jabber:client">`+
                     `<query xmlns="http://jabber.org/protocol/disco#info"/></iq>`);
 
-            iq = IQ_stanzas.pop();
-            expect(Strophe.serialize(iq)).toBe(
-                `<iq id="${iq.getAttribute('id')}" type="get" xmlns="jabber:client"><query xmlns="jabber:iq:roster"/></iq>`);
-
             iq = IQ_stanzas.pop();
             expect(Strophe.serialize(iq)).toBe(
                 `<iq from="romeo@montague.lit/orchard" id="${iq.getAttribute('id')}" to="montague.lit" type="get" xmlns="jabber:client">`+
@@ -58,6 +54,10 @@
                 `<iq from="romeo@montague.lit" id="${disco_iq.getAttribute('id')}" to="romeo@montague.lit" type="get" xmlns="jabber:client">`+
                     `<pubsub xmlns="http://jabber.org/protocol/pubsub"><items node="eu.siacs.conversations.axolotl.devicelist"/></pubsub></iq>`);
 
+            iq = IQ_stanzas.pop();
+            expect(Strophe.serialize(iq)).toBe(
+                `<iq id="${iq.getAttribute('id')}" type="get" xmlns="jabber:client"><query xmlns="jabber:iq:roster"/></iq>`);
+
             expect(sent_stanzas.filter(s => (s.nodeName === 'r')).length).toBe(2);
             expect(_converse.session.get('unacked_stanzas').length).toBe(4);
 
@@ -118,9 +118,9 @@
                 `<iq from="romeo@montague.lit/orchard" id="${iq.getAttribute('id')}" to="romeo@montague.lit" type="get" xmlns="jabber:client">`+
                     `<query xmlns="http://jabber.org/protocol/disco#info"/></iq>`);
 
-            iq = IQ_stanzas.pop();
-            expect(Strophe.serialize(iq)).toBe(
-                `<iq id="${iq.getAttribute('id')}" type="get" xmlns="jabber:client"><query xmlns="jabber:iq:roster"/></iq>`);
+            // We don't fetch the roster again because it's cached.
+            expect(_converse.session.get('roster_fetched')).toBeFalsy();
+            expect(IQ_stanzas.filter(iq => sizzle('query[xmlns="jabber:iq:roster"]', iq).pop()).length).toBe(0);
 
             await _converse.api.waitUntil('statusInitialized');
             done();

src/headless/converse-roster.js

@@ -438,33 +438,33 @@ converse.plugins.add('converse-roster', {
              * @returns {promise} Promise which resolves once the contacts have been fetched.
              */
             async fetchRosterContacts () {
-                let collection;
-                try {
-                    collection = await new Promise((resolve, reject) => {
+                if (_converse.session.get('roster_fetched')) {
+                    const result = await new Promise((resolve, reject) => {
                         this.fetch({
                             'add': true,
                             'silent': true,
                             'success': resolve,
-                            'error': (m, e) => reject(e)
+                            'error': (c, e) => reject(e)
                         });
                     });
-                } catch (e) {
-                    _converse.log(e, Strophe.LogLevel.ERROR);
-                    _converse.session.set('roster_fetched', false)
-                }
-                if (_converse.session.get('roster_fetched')) {
-                    /**
-                     * The contacts roster has been retrieved from the local cache (`sessionStorage`).
-                     * @event _converse#cachedRoster
-                     * @type { _converse.RosterContacts }
-                     * @example _converse.api.listen.on('cachedRoster', (items) => { ... });
-                     * @example _converse.api.waitUntil('cachedRoster').then(items => { ... });
-                     */
-                    _converse.api.trigger('cachedRoster', collection);
-                } else {
-                    _converse.send_initial_presence = true;
-                    return _converse.roster.fetchFromServer();
+                    if (u.isErrorObject(result)) {
+                        _converse.log(result, Strophe.LogLevel.ERROR);
+                        _converse.session.set('roster_fetched', false)
+                    } else {
+                        /**
+                         * The contacts roster has been retrieved from the local cache (`sessionStorage`).
+                         * @event _converse#cachedRoster
+                         * @type { _converse.RosterContacts }
+                         * @example _converse.api.listen.on('cachedRoster', (items) => { ... });
+                         * @example _converse.api.waitUntil('cachedRoster').then(items => { ... });
+                         */
+                        _converse.api.trigger('cachedRoster', result);
+                        return;
+                    }
                 }
+
+                _converse.send_initial_presence = true;
+                return _converse.roster.fetchFromServer();
             },
 
             subscribeToSuggestedItems (msg) {