public async Task ToDoHelperTest_GetAll_Success() { List <ToDo> to = new List <ToDo>(); Mock <IToDoService> mockTodoService = new Mock <IToDoService>(); mockTodoService.Setup(t => t.GetAll()).ReturnsAsync(to).Verifiable(); ToDoHelper todo = new ToDoHelper(mockTodoService.Object); var result = await todo.GetAll(); Assert.IsInstanceOfType(result, typeof(List <ToDo>)); }