compose: Use a placeholder when quoting and replying.

Use the placeholder `[Quoting…]` when quoting and replying before the
quote has been added to the message. Also, add tests to the
`compose_actions` Node tests for the new behavior.

Fix #10705.

frontend_tests/node_tests/compose_actions.js

@@ -29,6 +29,7 @@ var cancel = compose_actions.cancel;
 var get_focus_area = compose_actions._get_focus_area;
 var respond_to_message = compose_actions.respond_to_message;
 var reply_with_mention = compose_actions.reply_with_mention;
+var quote_and_reply = compose_actions.quote_and_reply;
 
 var compose_state = global.compose_state;
 
@@ -84,6 +85,14 @@ function stub_selected_message(msg) {
     });
 }
 
+function stub_channel_get(success_value) {
+    set_global('channel', {
+        get: function (opts) {
+            opts.success(success_value);
+        },
+    });
+}
+
 function assert_visible(sel) {
     assert($(sel).visible());
 }
@@ -244,6 +253,38 @@ run_test('reply_with_mention', () => {
     assert(compose_state.has_message_content());
 });
 
+run_test('quote_and_reply', () => {
+    var msg = {
+        type: 'stream',
+        stream: 'devel',
+        subject: 'python',
+        reply_to: 'bob',
+        sender_full_name: 'Bob Roberts',
+        sender_id: 40,
+    };
+    stub_selected_message(msg);
+    stub_channel_get({ raw_content: 'Testing.' });
+
+    current_msg_list.selected_id = function () {
+        return 100;
+    };
+
+    compose_ui.insert_syntax_and_focus = function (syntax) {
+        assert.equal(syntax, '[Quoting…]\n');
+    };
+
+    compose_ui.replace_syntax = function (syntax, replacement) {
+        assert.equal(syntax, '[Quoting…]');
+        assert.equal(replacement, 'Testing.');
+    };
+
+    var opts = {
+        reply_type: 'personal',
+    };
+
+    quote_and_reply(opts);
+});
+
 run_test('get_focus_area', () => {
     assert.equal(get_focus_area('private', {}), 'private_message_recipient');
     assert.equal(get_focus_area('private', {

static/js/compose_actions.js

@@ -390,15 +390,13 @@ exports.quote_and_reply = function (opts) {
     var message_id = current_msg_list.selected_id();
 
     exports.respond_to_message(opts);
+    compose_ui.insert_syntax_and_focus("[Quoting…]\n", textarea);
+
     channel.get({
         url: '/json/messages/' + message_id,
         idempotent: true,
         success: function (data) {
-            if (textarea.val() === "") {
+            compose_ui.replace_syntax('[Quoting…]', '```quote\n' + data.raw_content + '\n```', textarea);
-                textarea.val("```quote\n" + data.raw_content + "\n```\n");
-            } else {
-                textarea.val(textarea.val() + "\n```quote\n" + data.raw_content + "\n```\n");
-            }
             $("#compose-textarea").trigger("autosize.resize");
         },
     });