[FIX] web: correctly display nocontent helper if create='0'

When the root node of the arch has attribute 'create' set to '0',
the generated DOM element must have classname 'o_cannot_create'.
This is used to correctly display the nocontent helper (when there
is no record).

Before this rev., the helper indicated that the user can click on
'Create' to create a new record, even if the create action was
disabled. This was for example the case in Point of Sale > Orders.

addons/web/static/src/js/views/basic/basic_controller.js

@@ -46,6 +46,9 @@ var BasicController = AbstractController.extend(FieldManagerMixin, {
      * @returns {Deferred}
      */
     start: function () {
+        // add classname to reflect the (absence of) access rights (used to
+        // correctly display the nocontent helper)
+        this.$el.toggleClass('o_cannot_create', !this.activeActions.create);
         return this._super.apply(this, arguments)
                           .then(this._updateEnv.bind(this));
     },

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

@@ -84,7 +84,7 @@ QUnit.module('Views', {
     QUnit.module('ListView');
 
     QUnit.test('simple readonly list', function (assert) {
-        assert.expect(9);
+        assert.expect(10);
 
         var list = createView({
             View: ListView,
@@ -93,6 +93,9 @@ QUnit.module('Views', {
             arch: '<tree><field name="foo"/><field name="int_field"/></tree>',
         });
 
+        assert.notOk(list.$el.hasClass('o_cannot_create'),
+            "should not have className 'o_cannot_create'");
+
         // 3 th (1 for checkbox, 2 for columns)
         assert.strictEqual(list.$('th').length, 3, "should have 3 columns");
 
@@ -114,6 +117,24 @@ QUnit.module('Views', {
         list.destroy();
     });
 
+    QUnit.test('list with create="0"', function (assert) {
+        assert.expect(2);
+
+        var list = createView({
+            View: ListView,
+            model: 'foo',
+            data: this.data,
+            arch: '<tree create="0"><field name="foo"/></tree>',
+        });
+
+        assert.ok(list.$el.hasClass('o_cannot_create'),
+            "should have className 'o_cannot_create'");
+        assert.strictEqual(list.$buttons.find('.o_list_button_add').length, 0,
+            "should not have the 'Create' button");
+
+        list.destroy();
+    });
+
     QUnit.test('simple editable rendering', function (assert) {
         assert.expect(9);