Скачать или смотреть Resolving java.lang.NoClassDefFoundError in Android Espresso Testing: A Simple Fix

Discover a straightforward solution to the `NoClassDefFoundError` in Android Espresso UI tests that might be causing frustration during development.
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This video is based on the question https://stackoverflow.com/q/70104210/ asked by the user 'thebluepandabear' ( https://stackoverflow.com/u/15073157/ ) and on the answer https://stackoverflow.com/a/70149039/ provided by the user 'thebluepandabear' ( https://stackoverflow.com/u/15073157/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

If you're developing an Android application and making use of UI testing with Espresso, you may have encountered a frustrating error: java.lang.NoClassDefFoundError: Failed resolution of: Landroidx/test/platform/io/FileTestStorage;. This issue can arise when you attempt to run your UI tests, causing your progress to come to a halt.

In this guide, we will explore what triggers this error in Android Espresso and provide a simple, straightforward solution that you can apply to rectify the problem.

Understanding the Problem

When you see the error NoClassDefFoundError, it means the Android runtime was not able to find a specific class that it expected to use while executing your tests. In this case, it's looking for the FileTestStorage class provided by the AndroidX Testing library.

This specific error often stems from issues like:

Incompatibility between different versions of your dependencies.

Misconfigured Gradle build files.

Incorrectly simplified build configurations.

Scenario

In your case, the issue occurred while executing a UI test with the following code snippet:

[[See Video to Reveal this Text or Code Snippet]]

When you tried to execute this test, you encountered the NoClassDefFoundError related to FileTestStorage.

Solution to the Problem

Step-by-Step Fix

After exploring various avenues, it was found that the error could be resolved by modifying the build.gradle file. Specifically, the fix involves removing the following line from the dependencies section:

[[See Video to Reveal this Text or Code Snippet]]

By commenting out or deleting this line, the issue was resolved, and the tests were able to run successfully without throwing the NoClassDefFoundError.

Reasons Behind This Fix

Dependency Conflict: The presence of androidx.test:core-ktx:1.4.0 was conflicting with other testing libraries you were using.

Centralization of Test Dependencies: By simplifying and reducing the number of test dependencies, your build configuration can become more stable and less prone to conflicts.

Best Practices for Managing Dependencies

Regularly Update Dependencies: Ensure that your dependencies are up-to-date but compatible with each other. Use the latest stable releases or verify that specific versions work together correctly.

Avoid Unnecessary Dependencies: Only import libraries that are essential for your project's functionality to prevent unforeseen compatibility issues.

Test After Dependency Changes: Whenever you add or remove dependencies, run your tests to ensure everything is functioning as expected.

Conclusion

Running into a NoClassDefFoundError in Android Espresso can be frustrating, but it is often a solvable issue with a little attention to your build.gradle file. By simply removing the androidx.test:core-ktx dependency, you can restore the functionality of your UI tests.

Remember, effective dependency management is key to minimizing issues and keeping your development process smooth. Always keep an eye on version compatibility and be proactive about cleaning up your dependencies. Happy testing!