May 18, 2021

Your Guide to the Flutter Framework

Mobile Application Testing

Flutter is the newest framework to make a splash in the world of mobile app development. Here, we dive into the Flutter framework, its benefits and drawbacks, and the different ways to test a Flutter application. 

Read along or skip to the content that interests you the most. 

Table of Contents: 

What Is the Flutter Framework? 

Flutter is a free and open-source UI framework for creating native mobile applications from Google. Released in 2017, Flutter allows developers to build mobile applications with a single codebase and programming language. This capability makes building both iOS and Android apps simpler and faster. 

The Flutter framework consists of both a software development kit (SDK) and their widget-based UI library. This library consists of various reusable UI elements, such as sliders, buttons, and text inputs. 

Developers building mobile applications with the Flutter framework will do so using a programming language called Dart. With a syntax like JavaScript, Dart is a typed object programming language that focuses on front-end development. 

Related Reading: How to Do Flutter Integration Testing With Perfecto >>

Flutter Framework Architecture

Flutter is comprised of three architectural layers. Here is a quick breakdown of each one:

  1. Framework. This is the more “visible” part of Flutter’s technology. As already mentioned, this layer of Flutter’s architecture in based on Dart. The rich set of libraries in this layer can be divided into multiple layers, such as the basic foundational classes, the widget layer, and the rendering layer.
  2. Engine. This layer is written in C/C++. The engine provides a low-level implementation of the Flutter framework, as well as other core APIs, e.g. graphics, accessibility support, text layout, and plugin architecture.
  3. Embedder. The embedded is a platform-specific layer that allows the Flutter app to run on any OS. 
Flutter architecture

Let us understand the purpose of each type of testing with the following overview.: 

Unit Testing 

Unit tests for a Flutter app validate the behavior of a single method, function, or class. In other words, unit tests ensure that the method under test provides the expected result based on a given input. They help users write more testable and maintainable code. 

Users can run automated unit tests through the Flutter plugins for IntelliJ and VSCode. In addition to their support for running tests, IntelliJ and VSCode also provide the fastest feedback loop and allow users to set breakpoints.  

Widget Testing 

Widget tests, also known as component tests in other UI frameworks, verify that the widget’s UI looks and behaves as expected when responding to certain interactions. It is much more comprehensive than a unit test, as it involves multiple classes and requires a test environment that provides the appropriate widget lifecycle context. 

Yet at the same time, the widget’s test environment is a much simpler implementation than a more developed UI system. Flutter users should write widget tests for all common widgets being used for their applications. 

Integration Testing 

Integration tests test either the entire app or a large portion of the app. These tests verify application performance and ensure that all the widgets and services under test work together properly.  

Flutter users perform integration tests on either real devices or virtual devices, such as simulators and emulators. These tests run in two parts: deploying the application under test to the device (real or virtual) and then driving the application from a separate test suite. This checks to make sure that everything is working together as expected.  

Bottom Line 

The Flutter framework presents exciting opportunities for mobile app developers and businesses alike. Building iOS and Android applications with the same codebase on a highly user-friendly interface makes mobile app development fast and cost-effective.  

Combined with Perfecto, organizations can release high-quality Flutter applications quickly and easily. Learn more about our platform to learn about our Flutter testing capabilities in more detail. 

But wait, there's more! Now users can get the most out of Flutter with Perfecto's newly added integration testing capability. 

With Perfecto, you can enjoy Flutter integration support for both iOS and Android apps. That means testing to your heart’s desire on real devices (with virtual device testing to come) to ensure your app is of the highest quality. Flutter integration testing with Perfecto is a seamless, end-to-end process that allows you to feel confident that what you are building will be up to the task required of it.

See Perfecto in action by trying a free 14-day trial today.