Explicitly close files to prevent resource leak

[Stephen0512]

This pull request fixes a file-handling issue in the tests. The current implementation uses open() without explicitly closing the file for EXPECT_DATA, which can potentially lead to resource leaks. While Python's garbage collector will eventually close the file once it is no longer referenced, it is generally better practice to explicitly close files or use a context manager.

This change replaces the direct open() call with a with statement to ensure proper file closure and follow Python best practices. The issue was identified during an ongoing research project.

[wyapx]

Although it only runs on pytest to identify potential unexpected error, but that is a good point.

A good patch, thanks