typeahead: Don't match descriptions for streams and user groups.

Uptil now, both names and descriptions of streams and user groups were
matched to show the typeahead suggestions. This led to unexpected
behaviour like for a clear mention of a certain stream, the typeahead
menu suggested a completely different stream which had a mention of
the first stream in it's description.

To prevent such bugs and also since description matching is not really
useful for streams and user groups, only names will be matched.

frontend_tests/node_tests/composebox_typeahead.js

@@ -953,7 +953,7 @@ test("initialize", ({override, override_rewire, mock_template}) => {
         fake_this.$element.closest = () => [];
         fake_this.options = options;
         let actual_value = options.source.call(fake_this, "test #s");
-        assert.deepEqual(sorted_names_from(actual_value), ["Denmark", "Sweden", "The Netherlands"]);
+        assert.deepEqual(sorted_names_from(actual_value), ["Sweden", "The Netherlands"]);
         assert.ok(caret_called);
 
         // options.highlighter()
@@ -1590,15 +1590,15 @@ test("typeahead_results", () => {
     assert_mentions_matches("delia lear", []);
     assert_mentions_matches("Mark Tw", [twin1, twin2]);
 
+    // Earlier user group and stream mentions were autocompleted by their
+    // description too. This is now removed as it often led to unexpected
+    // behaviour, and did not have any great discoverability advantage.
+
     // Autocomplete user group mentions by group name.
     assert_mentions_matches("hamletchar", [hamletcharacters]);
 
-    // Autocomplete user group mentions by group descriptions.
-    assert_mentions_matches("characters ", [hamletcharacters]);
-    assert_mentions_matches("characters of ", [hamletcharacters]);
-    assert_mentions_matches("characters o ", []);
-    assert_mentions_matches("haracters of hamlet", []);
-    assert_mentions_matches("of hamlet", [hamletcharacters]);
+    // Verify we're not matching on a terms that only appear in the description.
+    assert_mentions_matches("characters of", []);
 
     // Autocomplete by slash commands.
     assert_slash_matches("me", [me_slash]);
@@ -1607,14 +1607,15 @@ test("typeahead_results", () => {
     assert_slash_matches("light", [light_slash]);
     assert_slash_matches("day", [light_slash]);
 
-    // Autocomplete stream by stream name or stream description.
+    // Autocomplete stream by stream name
     assert_stream_matches("den", [denmark_stream, sweden_stream]);
     assert_stream_matches("denmark", [denmark_stream]);
     assert_stream_matches("denmark ", []);
     assert_stream_matches("den ", []);
-    assert_stream_matches("cold", [sweden_stream, denmark_stream]);
     assert_stream_matches("the ", [netherland_stream]);
-    assert_stream_matches("city", [netherland_stream]);
+    // Do not match stream descriptions
+    assert_stream_matches("cold", []);
+    assert_stream_matches("city", []);
 });
 
 test("message people", ({override}) => {

static/js/composebox_typeahead.js

@@ -96,13 +96,8 @@ export function query_matches_person(query, person) {
     return typeahead.query_matches_source_attrs(query, person, ["full_name", email_attr], " ");
 }
 
-export function query_matches_name_description(query, user_group_or_stream) {
-    return typeahead.query_matches_source_attrs(
-        query,
-        user_group_or_stream,
-        ["name", "description"],
-        " ",
-    );
+export function query_matches_name(query, user_group_or_stream) {
+    return typeahead.query_matches_source_attrs(query, user_group_or_stream, ["name"], " ");
 }
 
 function get_stream_or_user_group_matcher(query) {
@@ -110,7 +105,7 @@ function get_stream_or_user_group_matcher(query) {
     query = typeahead.clean_query_lowercase(query);
 
     return function (user_group_or_stream) {
-        return query_matches_name_description(query, user_group_or_stream);
+        return query_matches_name(query, user_group_or_stream);
     };
 }
 
@@ -476,7 +471,7 @@ export function get_person_suggestions(query, opts) {
 
     const groups = user_groups.get_realm_user_groups();
 
-    const filtered_groups = groups.filter((item) => query_matches_name_description(query, item));
+    const filtered_groups = groups.filter((item) => query_matches_name(query, item));
 
     /*
         Let's say you're on a big realm and type

static/js/pill_typeahead.js

@@ -16,7 +16,7 @@ function person_matcher(query, item) {
 
 function group_matcher(query, item) {
     if (user_groups.is_user_group(item)) {
-        return composebox_typeahead.query_matches_name_description(query, item);
+        return composebox_typeahead.query_matches_name(query, item);
     }
     return false;
 }