message_list_view: Remove dead next_is_same_sender code.

The `next_is_same_sender` has no effect on the CSS of the message
displayed and the JS changes seem to have no effect too.

See cc8021a742 for more details.

frontend_tests/node_tests/message_list_view.js

@@ -486,7 +486,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_append_message_same_topic() {
@@ -506,7 +505,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert_message_list_equal(result.append_messages, [message2]);
-        assert_message_list_equal(result.rerender_messages_next_same_sender, [message1]);
     })();
 
     (function test_append_message_different_topic() {
@@ -525,7 +523,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_append_message_different_topic_and_days() {
@@ -543,7 +540,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
         assert.equal(message_group2.group_date_divider_html, "900000000 - 1000000");
     })();
 
@@ -562,7 +558,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, [message2]);
-        assert.deepEqual(result.rerender_messages_next_same_sender, [message1]);
         assert.ok(list._message_groups[0].message_containers[1].want_date_divider);
     })();
 
@@ -582,7 +577,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_append_message_same_topic_me_message() {
@@ -603,7 +597,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert.deepEqual(result.rerender_groups, []);
         assert_message_list_equal(result.append_messages, [message2]);
-        assert_message_list_equal(result.rerender_messages_next_same_sender, [message1]);
     })();
 
     (function test_prepend_message_same_topic() {
@@ -625,7 +618,6 @@ test("merge_message_groups", () => {
             build_message_group([message2, message1]),
         ]);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_prepend_message_different_topic() {
@@ -643,7 +635,6 @@ test("merge_message_groups", () => {
         assert_message_groups_list_equal(result.prepend_groups, [message_group2]);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_prepend_message_different_topic_and_day() {
@@ -663,7 +654,6 @@ test("merge_message_groups", () => {
         assert_message_groups_list_equal(result.prepend_groups, [message_group2]);
         assert.deepEqual(result.rerender_groups, [message_group1]);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_prepend_message_different_day() {
@@ -683,7 +673,6 @@ test("merge_message_groups", () => {
         assert.deepEqual(result.prepend_groups, []);
         assert_message_groups_list_equal(result.rerender_groups, [message_group2]);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 
     (function test_prepend_message_historical() {
@@ -702,14 +691,9 @@ test("merge_message_groups", () => {
         assert_message_groups_list_equal(result.prepend_groups, [message_group2]);
         assert.deepEqual(result.rerender_groups, []);
         assert.deepEqual(result.append_messages, []);
-        assert.deepEqual(result.rerender_messages_next_same_sender, []);
     })();
 });
 
-// TODO: Add a test suite for rerender_messages_next_same_sender() that includes cases
-// where new messages added via local echo have a different date from
-// the older messages.
-
 test("render_windows", () => {
     // We only render up to 400 messages at a time in our message list,
     // and we only change the window (which is a range, really, with

static/js/message_list_view.js

@@ -426,9 +426,6 @@ export class MessageListView {
         let prev;
 
         const add_message_container_to_group = (message_container) => {
-            if (same_sender(prev, message_container)) {
-                prev.next_is_same_sender = true;
-            }
             current_group.message_containers.push(message_container);
         };
 
@@ -530,9 +527,6 @@ export class MessageListView {
             ) {
                 first_msg_container.include_sender = false;
             }
-            if (same_sender(last_msg_container, first_msg_container)) {
-                last_msg_container.next_is_same_sender = true;
-            }
             first_group.message_containers = first_group.message_containers.concat(
                 second_group.message_containers,
             );
@@ -563,7 +557,6 @@ export class MessageListView {
             prepend_groups: [],
             rerender_groups: [],
             append_messages: [],
-            rerender_messages_next_same_sender: [],
         };
         let first_group;
         let second_group;
@@ -623,7 +616,6 @@ export class MessageListView {
         } else {
             if (was_joined) {
                 // rerender the last message
-                message_actions.rerender_messages_next_same_sender.push(prev_msg_container);
                 message_actions.append_messages = new_message_groups[0].message_containers;
                 new_message_groups = new_message_groups.slice(1);
             } else if (first_group !== undefined && second_group !== undefined) {
@@ -837,25 +829,6 @@ export class MessageListView {
             }
         }
 
-        // Update the rendering for message rows which used to be last
-        // and now know whether the following message has the same
-        // sender.
-        //
-        // It is likely the case that we can just remove the block
-        // entirely, since it appears the next_is_same_sender CSS
-        // class doesn't do anything.
-        if (message_actions.rerender_messages_next_same_sender.length > 0) {
-            const targets = message_actions.rerender_messages_next_same_sender;
-
-            for (const message_container of targets) {
-                const $row = this.get_row(message_container.msg.id);
-                $row.find("div.messagebox").toggleClass(
-                    "next_is_same_sender",
-                    message_container.next_is_same_sender,
-                );
-            }
-        }
-
         // Insert new messages in to the last message group
         if (message_actions.append_messages.length > 0) {
             $last_message_row = $table.find(".message_row").last().expectOne();

static/styles/zulip.css

@@ -1711,11 +1711,6 @@ div.focused_table {
     background-color: transparent;
 }
 
-.next_is_same_sender {
-    border-bottom: 0;
-    padding-bottom: 0;
-}
-
 .inline_profile_picture {
     display: inline-block;
     width: 35px;

static/templates/single_message.hbs

@@ -5,7 +5,7 @@
     {{#if want_date_divider}}
     <div class="date_row no-select" {{#if msg/is_stream}}style="box-shadow: inset 3px 0px 0px -1px {{background_color}}, -1px 0px 0px 0px {{background_color}};"{{/if}}>{{{date_divider_html}}}</div>
     {{/if}}
-    <div class="messagebox {{#if next_is_same_sender}}next_is_same_sender{{/if}}"
+    <div class="messagebox"
       {{#if msg/is_stream}}style="box-shadow: inset 3px 0px 0px -1px {{background_color}}, -1px 0px 0px 0px {{background_color}};"{{/if}}>
         <div class="messagebox-content">
             {{> message_body}}