const Endless = imports.gi.Endless; const Gtk = imports.gi.Gtk; const Lang = imports.lang; const TestContainer = new Lang.Class({ Name: 'TestContainer', Extends: Endless.CustomContainer, _init: function (params) { this.parent(params); }, vfunc_size_allocate: function (alloc) { this.parent(alloc); } }); Gtk.init(null); describe("CustomContainer", function () { it("Instantiates a CustomContainer subclass to make sure no exceptions/segfaults", function () { let createContainer = function () { let container = new TestContainer(); }; expect(createContainer).not.toThrow(); }); });