Widget testing is another form of software testing that focuses on how well all the different components of a UI function. For Flutter apps, Widgets play a significant role as they are needed to ensure that every element of the UI works as intended. Verifying the functionality and behavior of the individual user interface elements within the application tests a Flutter app's different interactive features or widgets. The ultimate goal of a widget test is to ensure that all the user interface elements of a Flutter app produce the desired output and behaves according to the user's expectations.
Widget testing is a form of software testing used to ensure that the user interface of an app works and functions correctly. Widgets are the building blocks that make up a Flutter application and are needed to ensure that every component of the UI works effectively.
Another name for Widget testing is Component testing. It is a critical part of the development process as it helps identify and address any issues early enough before an app is finally deployed. Testing a widget involves various classes and requires a test environment that provides the most suitable widget lifecycle context.
For example, when carrying out a Widget test on a newly created application at Fetchly, the Widget being tested has to receive and respond to user actions and events, render layouts, and initialize child widgets. A widget test is, therefore, more detailed than a
unit test. However, like a unit test, a widget test's environment is replaced with a more straightforward implementation than a full-blown UI system.
Also, the WidgetTester utility can be used for other things while testing, such as finding a part in the widget tree, sending input to a widget, and confirming values.
There is a lot to learn about widget testing for Flutter apps, and this article will provide an overview of the concept, why it is essential, and how to carry it out.
What is Widget Testing?
Widget testing is a type of software testing that focuses on the user interface of an app.
For Flutter apps, widget testing works by verifying the functionality and behavior of the individual user interface elements within the application.
It involves testing a Flutter app's various components or widgets, such as buttons, text fields, and other interactive elements. The goal is to ensure that all the user interface elements work as expected, producing the desired output and behaving according to the user's expectations.
The design team at
Fetchly Labs pays close attention to how the interface of a web or mobile app turns out and how it functions. Therefore UI and UX designers work with developers and QA to ensure that every user interface element within an application works as intended before deployment.
Why is Widget Testing Important For Flutter Apps?
User interface elements are integral to any app, and its user experience (UX) largely depends on them. By testing the widgets of a Flutter app, Fetchly developers can ensure that the user interface elements function correctly, providing the desired output and behaving according to the user's expectations.
For example, if a Text widget doesn't have the specific text, widget testing will highlight the error by stating that the Text widget doesn't contain the text. This helps to provide a seamless user experience and limits the risk of errors and bugs finding their way into the platform.
Widget testing is also helpful because it helps ensure the app is accessible, usable, and aesthetically pleasing.
How to Carry Out Widget Testing for Flutter Apps?
1. Create or select the Widget to Test;
The first step is creating or selecting the Widget to be tested. This could be a text box, a drop-down menu, a button, or a user interface element. Once the Widget has been selected, the next step is to write a test that will verify the functionality and behavior of the Widget.
2. Write the Test;
To write your test, you must create a dedicated test file such as <widget_name>_test.dart in the app's /test directory. When mocking your test, consider the different user scenarios and how the Widget should behave in each case. For example, if the Widget is a text box, the test should verify that the text can be entered, edited, and cleared. If the Widget is a button, the test should ascertain that clicking the button would perform the function it ought to.
You should be familiar with the following:
- Using the testWidgets function - where the bulk of your test assertions will be.
- The WidgetTester class is responsible for building the widget within the test code.
- The Finder class (for selecting your widget in the test code itself).
- Using Matchers functions that act as assertion verifiers within your code.
These are used within the expected clauses in your test file, and If you have ever used chai in a Javascript environment, they all have very similar objectives.
3. Run the Tests;
Once the tests have been written, the next step is to run them, and this can be done using the flutter command line with the following command:
flutter run test/<widget_name>_test.dart
When running the tests, confirm that your Flutter app passes all the tests and produces the expected outcome.
4. Analyze the Results;
After running the tests, analyze the results. The analysis involves reviewing the test results and identifying any issues or bugs to be reported and fixed immediately.
5. Debug the Widgets;
If any issues are encountered during testing, it is important to debug the widgets using
Flutter debugging tools. These tools allow developers to search through the code and identify any issues.
6. Refine the Widgets;
Many times after patching issues within a codebase, more efficient patterns might reveal themselves. This is usually a good moment to sit back and perform any refactoring that might be beneficial in the long run. Doing so will ensure your app grows sustainably and free of code debt.
Final Remarks
Widget testing is often beneficial to the development process for Flutter apps. It helps ensure the user interface works correctly and is accessible, usable, and visually correct.
Through the steps outlined in this article, Fetchly software engineers ensure that the user interface elements of their Flutter app function correctly and behave according to the user's expectations. Also, following the steps will help promote a seamless user experience and reduce the risk of errors and bugs in a Flutter app.
*This is not the official Fetchly opinion but the opinion of the writer who is employed by Fetchly*
