How to Generate and Analyze a Flutter Test Coverage Report

In today’s fast-paced world of app development, ensuring the quality of your Flutter application is more critical than ever. With a myriad of devices, screen sizes, and user expectations, developers face the daunting task of crafting apps that are not only functional but also reliable. This is where Flutter test coverage comes into play.

It is a vital aspect of any software development process, and when it comes to Flutter, it’s no different. In this blog, we will discuss Flutter test coverage, its significance, different techniques, and best practices to achieve high coverage. Let’s start with Flutter.

Flutter is the most popular cross-platform mobile framework used by developers globally. Statistics show that over 46% of software developers use Flutter. That is, roughly one-third of mobile developers use cross-platform technologies or frameworks.

What is Flutter Test Coverage?

Flutter test coverage measures the percentage of your app’s code that runs during automated or manual testing. It’s a key indicator of how thoroughly your tests validate your application. The higher the coverage percentage, the more parts of your code are being tested.

For example, if your Flutter test coverage is 80%, it means your tests execute 80% of your app’s source code. This helps you identify which parts of the code remain untested so you can focus your testing efforts there.

Note: Several coverage analysis techniques can help you measure and understand these metrics in detail.

A high coverage rate is generally considered a good practice. It increases the likelihood of detecting bugs early and ensures your app behaves as expected. However, remember that 100% coverage doesn’t guarantee a bug-free app. It’s one of several quality metrics that contribute to overall code health.

Tip: To learn more about Flutter testing and why it’s essential, check out our detailed guide on Flutter app testing.

You can test Flutter apps in two ways:

Leveraging a low-code test automation platform like Testsigma, which eliminates the need to write or manage test scripts manually.

Using Flutter’s built-in testing framework

Leveraging a low-code test automation platform like Testsigma, which eliminates the need to write or manage test scripts manually.

Pre-Requisite Required to Do Flutter Test Coverage

Before you can generate and analyze a Flutter test coverage report, you need to make sure your environment and test setup are ready. Here’s what you’ll need:

1. A Properly Configured Flutter Environment

Ensure Flutter and Dart are installed and configured on your system. You can verify this by running:

1
2flutter doctor
3

This command checks your system setup and confirms that all required components are installed and configured correctly.

2. Test Cases Written for Your App

You can’t measure test coverage without tests! Write clear and meaningful unit, widget, and integration tests that cover different layers of your application. Use descriptive test names and verify all core functionalities, edge cases, and user flows.

3. Automated Test Execution Setup

Automate your Flutter test runs using:

1
2flutter test –coverage
3

This command not only runs your tests but also generates a coverage report automatically.

4. Lcov Installed

To visualize the test coverage data, install LCOV, a coverage analysis tool that helps convert the raw coverage data into human-readable reports.
For macOS users:

1
2brew install lcov
3

After running your tests, you can generate an HTML report with:

1
2genhtml coverage/lcov.info -o coverage/html
3
4open coverage/html/index.html
5

How Do You Maximize Flutter Test Coverage?

Maximizing Flutter test coverage means ensuring that your tests exercise as much of your app’s codebase as possible, across logic, UI, and integrations. It’s not just about hitting a high percentage; it’s about testing the right parts of your code effectively. Here are the most effective strategies to achieve that:

1. Write Comprehensive Unit Tests

Unit tests validate the smallest units of your code, like  functions, classes, and methods in isolation. To boost coverage:

• Write tests for all critical business logic and edge cases.
• Use the test() function from Flutter’s test package to validate expected outcomes.
• Mock dependencies to isolate each function’s behavior using tools like mockito.

Tip: Aim for at least 70–80% coverage through unit tests, they’re fast, reliable, and easy to maintain.

2. Add Widget Tests for UI Validation

Widget tests (or component tests) verify how your widgets render and respond to user interactions. To maximize coverage here:

• Test both visual rendering and functional behavior of widgets.
• Use the testWidgets() function to simulate taps, scrolls, and input events.
• Ensure every major screen and custom widget has at least one test.

Example:

1
2
3testWidgets(‘Login button navigates to dashboard’, (tester) async {
4
5  await tester.pumpWidget(MyApp());
6
7  await tester.tap(find.text(‘Login’));
8
9  await tester.pumpAndSettle();
10
11  expect(find.text(‘Dashboard’), findsOneWidget);
12
13});
14
15

3. Perform Integration Tests

Integration tests confirm that different parts of your app work seamlessly together, from the UI to backend services.

• Use Flutter’s integration_test package to automate end-to-end user flows.
• Simulate real-world interactions like form submissions, navigation, or API responses.
• Automate these tests regularly to track coverage trends over time.

4. Leverage Low-Code Test Automation

Manually maintaining test scripts can slow you down. Tools like Testsigma simplify this process by allowing you to:

• Automate Flutter app testing without writing code.
• Run tests across multiple devices, browsers, and OS versions.
• Use parallel testing to execute multiple test cases simultaneously — covering more ground in less time.

This approach accelerates test creation and boosts coverage across platforms.

5. Include Black-Box and Exploratory Tests

Don’t limit testing to code-level checks. Perform black-box testing to validate user-facing behavior and real-world interactions. Low-code automation tools like Testsigma can run black-box tests at scale, helping ensure your app performs as expected under varied scenarios.

Automated Flutter Testing with Testsigma for High Coverage

Testsigma is a robust, low-code, cloud-based test automation platform that lets you automate web, mobile, desktop, and API tests in one place. With Testsigma, you can automate Flutter tests as well. 

Also, you can create Flutter tests using NLPs or the record feature (That is, you can interact with the application and run them as automated tests on the cloud).

Let me show you how you can automate Flutter tests without writing any line of code.

Step 1: Log in to the application. Create a new project or use an existing project. To do so, go to Create – New Project.

Step 2: Now, you need to upload the APK file to start creating test cases. You can upload APK files in two ways.

• Go to Test Data – Upload and upload your APK file to create test cases.

 

 

• Once you’ve created a project, you will be redirected to create test cases, and when you click on Record, you will prompted to the below screen. You can upload your APK files here, too.

 

Step 3: Once the APK file is uploaded, you can choose the Test Lab – Testsigma Lab or your local device to create test cases. 

In this instance, I have chosen the Testsigma Lab. Here, I have chosen a device from the list of devices supported. For example, Google Pixel 7.

Also, when you choose your Test Lab as Local Devices, you will be allowed to connect your local device to Testsigma. And, as you interact with the app, Testsigma can run them as automated tests later on the cloud.

Step 4: On clicking Record, your application will load on a mobile device on the cloud, where you can start creating your test cases by using our intuitive interface. 

Step 5: Once the test cases have been created, click on Run to execute tests.

Also, with Testsigma, you can scan and test advanced features, including QR codes, using the Camera image injection feature. When will it be helpful? Suppose your application has a QR code, and you want to test if users are able to scan and do permitted actions. That’s when this feature will help.

Here are some of the benefits of automating Flutter testing with Testsigma,

Scriptless Test Automation: Testsigma allows you to create and manage tests without writing any code. This makes testing accessible for both technical and non-technical teams.

Cross-Browser Testing: Testsigma supports testing across multiple browsers, platforms, versions, and devices, ensuring that your Flutter application works consistently across different environments. This is especially crucial for Flutter because it is a cross-platform framework.

Parallel Testing: You can execute tests in parallel, significantly reducing the overall test execution time.

AI-Powered Testing: Testsigma uses AI to help identify elements on the screen, making it easier to create and maintain tests, even as the application evolves.

Third-party Integrations: Testsigma can integrate with popular CI/CD, product management, collaboration, and bug-tracking tools, allowing you to incorporate automated testing into your development workflow seamlessly.

Best Practices to Maximize Flutter Test Coverage

Here are some of the best practices to maximize Flutter test coverage,

• Regularly review and update your tests as your application evolves.
• Make sure to cover edge cases and boundary conditions in your tests. This includes testing for valid and invalid inputs as well.
• As your codebase evolves, make sure to update your tests to reflect any changes in behavior or functionality.
• Integrate tests into your DevOps and CI/CD pipeline.
• Perform thorough unit tests to ensure the code works as expected. This will help catch bugs, if any, in the early stages and can be fixed to avoid serious damage in the later stages.
• Use automated testing tools to get high coverage as it helps streamline the testing process and reduce manual testing efforts.

By combining a mix of unit tests, widget tests, and integration tests, along with automation tools like Testsigma, you can achieve high coverage for your Flutter applications.

Flutter Test Coverage Command

Once the developer completes writing unit tests, they can check the code coverage locally using the below Flutter code test coverage command,

Here’s a breakdown of the Flutter command,

• flutter test: This command is used to run Flutter unit tests.
• –coverage: This is used to generate a code coverage report. When you include this option in the Flutter test command, Flutter collects information about the parts of your code that are executed during the tests.

After running the tests with –coverage, it generates a Flutter test coverage report, typically in the coverage/lcov-report directory. This Flutter test coverage report can be opened in a web browser to visualize the coverage details.

Take a look at the snippet to understand how the Flutter unit test coverage command works,

This is how the Flutter test coverage report will look like when opened in a web browser.

Flutter Test Coverage Extension

After installing the Flutter Coverage extension, it will be available in your testing tab, providing the coverage information for all files and folders. Also, you will see three different icons indicating areas of your code that require further testing,

• ✅ more than 70% coverage
• ⚠️ between 50% – 70% coverage
• ❌ less than 50% coverage

An alternate way to perform Flutter testing is to use a test automation platform like Testsigma, where testers can easily automate mobile app testing along with web, desktop, and API tests in one platform. Also, by automating tests, testers can focus on other critical tasks, such as exploratory testing. 

Automate your black box tests for flutter apps, 10x faster, with Testsigma

How Testsigma Can Increase Your Flutter Test Coverage?

Low-code test automation is a valuable way to increase coverage in Flutter app development. Here’s how low-code test automation can increase the Flutter test coverage

• Low-code test automation platforms allow testers to create automated tests using NLPs, record-and-play features, etc. It accelerates the test creation, allowing testers to cover more test scenarios in less time.
• Also, low-code platforms do not require much coding skills, which makes Flutter testing accessible to both technical and non-technical users. It expands the pool of individuals who can contribute to testing efforts.
• Testsigma,  a low-code test automation tool, supports over 3000+ real devices/tablets and 1000+ browser/OS combo. This means that you can easily create tests that cover multiple OS, browsers, versions, and devices, increasing the scope of your coverage.
• Parallel testing is another benefit. Parallel test execution allows you to run multiple tests simultaneously. This significantly speeds up the testing process, enabling you to cover more ground in less time.
• Makes your Flutter testing 10x faster and ship products at a 10x faster rate. So, you can save time, resources, and efforts. This way, you can test and cover more codebase.

Conclusion

Achieving 100% coverage may not always be feasible or necessary, but striving for a high level of coverage is essential for building reliable and resilient applications. It’s a crucial part of the development process that pays off in the long run, saving time and resources in debugging and maintenance.

As discussed above, automated testing tools can help you achieve higher coverage. Automation helps you save time, resources, and effort. Sign up to Testsigma and start automating your tests in less than 2 minutes.

Frequently Asked Questions

How Can the Code Coverage DATA From Flutter Tests Be Displayed?

You can view the code coverage data from Flutter tests using the following steps,

1. Install lcov in Mac
2. Run tests, generate coverage files, and convert to HTML
3. Open coverage report in the browser

What Are the Three Types of Testing Supported by Flutter?

The three types of testing supported by Flutter,

• Unit tests
• Widget tests
• Integration tests

What is the Purpose of Coverage?

Increasing coverage means creating more test cases, resulting in fewer defects and less work in later stages, ultimately leading to higher customer satisfaction with a better product.

What is Flutter Test Coverage Vs Code?

The difference between code coverage and test coverage is simple. Flutter test coverage refers to the extent to which a set of tests covers the codebase of a program. In contrast, code coverage refers to the percentage of code that has been executed by the test suite.