Enhancements and Modernization of Test Classes

[ogzugru]

Hello,

I've submitted a pull request with some improvements to enhance the code quality of project. Here’s a quick summary:

JUnit5 Tests to Default Visibility: Removed "public" keyword from test classes and methods for cleaner, more idiomatic JUnit5 code. Assertion Argument Order: Corrected the order of arguments in assertions for consistency. Removed Unused Imports: Cleaned up the codebase by removing unnecessary imports. Java 11 String Handling: Updated file handling with Files.readString() and Files.writeString() for better efficiency and readability.

These changes are fully tested and aim to contribute to the project’s maintainability. Looking forward to any feedback and hoping for a smooth merge.

Thanks for your consideration!

Best regards,