[FIX] web: add record in list with sample data: no flickering

Have an editable list view with sample data (sample="1" and no
record). Before this commit, there was a flickering when the user
clicked on "New" to add a record. Indeed, the list was first
re-rendered without the sample mode (i.e. without the opacity style
and no content helper), but still with the sample records. With
this commit, we wait for the reload to be done before leaving the
sample mode, s.t. when the list is re-rendered, we don't have
sample records anymore.

Part-of: odoo/odoo#132802

addons/web/static/src/model/relational_model/dynamic_list.js

@@ -210,10 +210,10 @@ export class DynamicList extends DataPoint {
         return unlinked;
     }
 
-    _leaveSampleMode() {
+    async _leaveSampleMode() {
         if (this.model.useSampleModel) {
+            await this._load(this.offset, this.limit, this.orderBy, this.domain);
             this.model.useSampleModel = false;
-            return this._load(this.offset, this.limit, this.orderBy, this.domain);
         }
     }
 

addons/web/static/tests/views/list_view_tests.js

@@ -19407,6 +19407,7 @@ QUnit.module("Views", (hooks) => {
         assert.strictEqual(input, document.activeElement);
         assert.strictEqual(input.value, "Value 1");
     });
+
     QUnit.test("monetary field display for rtl languages", async function (assert) {
         patchWithCleanup(localization, {
             direction: "rtl",
@@ -19442,4 +19443,40 @@ QUnit.module("Views", (hooks) => {
             "Monetary cells should have ltr direction"
         );
     });
+
+    QUnit.test("add record in editable list view with sample data", async function (assert) {
+        serverData.models.foo.records = [];
+        let def;
+        await makeView({
+            type: "list",
+            resModel: "foo",
+            serverData,
+            arch: '<tree sample="1" editable="top"><field name="int_field"/></tree>',
+            noContentHelp: "click to add a record",
+            mockRPC(route, args) {
+                if (args.method === "unity_web_search_read") {
+                    return def;
+                }
+            },
+        });
+
+        assert.containsOnce(target, ".o_view_sample_data");
+        assert.containsOnce(target, ".o_view_nocontent");
+        assert.containsN(target, ".o_data_row", 10);
+
+        def = makeDeferred();
+        await clickAdd();
+
+        assert.containsOnce(target, ".o_view_sample_data");
+        assert.containsOnce(target, ".o_view_nocontent");
+        assert.containsN(target, ".o_data_row", 10);
+
+        def.resolve();
+        await nextTick();
+
+        assert.containsNone(target, ".o_view_sample_data");
+        assert.containsNone(target, ".o_view_nocontent");
+        assert.containsOnce(target, ".o_data_row");
+        assert.containsOnce(target, ".o_data_row.o_selected_row");
+    });
 });