dropdown_list_widget: Add basic tests.

frontend_tests/node_tests/dropdown_list_widget.js

@@ -0,0 +1,47 @@
+zrequire('dropdown_list_widget');
+zrequire('scroll_util');
+set_global('$', global.make_zjquery());
+
+const noop = () => {};
+const _list_render = {
+    create: () => {
+        return { init: noop };
+    },
+};
+set_global('list_render', _list_render);
+
+run_test('basic_functions', () => {
+    let updated_value;
+    const opts = {
+        setting_name: 'my_setting',
+        data: ['one', 'two', 'three'].map(x => ({name: x, value: x})),
+        value: 'one',
+        on_update: (val) => { updated_value = val; },
+        default_text: i18n.t("not set"),
+        render_text: (text) => `rendered: ${text}`,
+    };
+
+    const input_group = $(".input_group");
+    const reset_button = $('.dropdown_list_reset_button');
+    input_group.set_find_results('.dropdown_list_reset_button', reset_button);
+    $("#my_setting_widget #my_setting_name").closest = () => input_group;
+    const $widget = $("#my_setting_widget #my_setting_name");
+
+    const widget = dropdown_list_widget(opts);
+
+    assert.equal(widget.value(), 'one');
+    assert.equal(updated_value, undefined);  // We haven't 'updated' the widget yet.
+    assert(reset_button.visible());
+
+    widget.update('two');
+    assert.equal($widget.text(), 'rendered: two');
+    assert.equal(widget.value(), 'two');
+    assert.equal(updated_value, 'two');
+    assert(reset_button.visible());
+
+    widget.update(null);
+    assert.equal($widget.text(), 'translated: not set');
+    assert.equal(widget.value(), '');
+    assert.equal(updated_value, null);
+    assert(!reset_button.visible());
+});