Parameterize tests in AuthorTest and AuthorListTest

[YizhangCao]

Refs JabRef#676

This PR parameterizes tests in AuthorTest and AuthorListTest to reduce code duplication and improve test maintainability.

My classmates are also contributing to the same issue.

@espertusnu

Testing

   ./gradlew test --tests AuthorTest
   ./gradlew test --tests AuthorListTest

[calixtus]

There seems to be something wrong with either github or your local configuration:

[calixtus]

Binaries

[espertusnu]

@YizhangCao seems to have saved the files with the wrong encoding.

@Siedlerchr I see you closed the PR. Should he not fix this?

[calixtus]

We got a few low-quality and ai generated prs the last days. Looks like @Siedlerchr overlooked that this pr was from one of the students of your course, when he closed it. Sorry.

Yes, please have the student update the branch with files in the correct encoding.

[YizhangCao]

Thank you @calixtus and @espertusnu for catching this encoding issue! I apologize for the problem.

I've now fixed the file encoding to UTF-8. The issue occurred because I used PowerShell's redirection operator which saved the files as UTF-16 instead of UTF-8.

After pushing I saw all tests are passed, right now I will fix [Source Code Tests / Checkstyle (pull_request)] and [Source Code Tests / Unit tests – jablib (pull_request)

[koppor]

Please refactor using the knowledge provided at https://devdocs.jabref.org/code-howtos/testing.html#use-paramterizedtests

[YizhangCao]

Thank you @koppor and @calixtus for the review!

I've made the following fixes:

1. Fixed all EMPTY_AUTHOR test cases in AuthorListTest.java to expect empty string ('') instead of null
2. Reformatted all @CsvSource annotations in AuthorTest.java to have one test case per line for better readability, following the guidelines at https://devdocs.jabref.org/code-howtos/testing.html#use-paramterizedtests