FreezingArchRule generates file missing newline

[pkubowicz]

To reproduce:

1. use FreezingArchRule
2. run ArchUnit test to let the rule generate file in archunit_store/
3. commit the file to Git repository
4. see the diff using git show
5. open the file in IntelliJ, make any change (remove a random line), save, commit
6. see the diff using git show

• Expected: nice Git diff
• Actual: FreezingArchRule generates a file that shows in Git diff as \ No newline at end of file (step 4)

Additionally, well-behaving editors like vim or IntelliJ put newline character at the end of text files. This is because a file without final newline is not a proper text file. Anyway, as result, if you manually edit generated file (step 5), you generate a fake change in the last line by inserting the missing newline (step 6). Run ArchUnit test again, and you will play ping-pong with Git, doing nonsense changes to the last line.

Suggested solution: Change com.tngtech.archunit.library.freeze.ViolationStoreFactory.TextFileBasedViolationStore#write and stop join ing violations with "\n". Just append \n after each violation and all will be fine.

I can open a PR if you don't have time to fix, just let me know you're fine with the solution.

[codecholeric]

I agree, I've also stumbled over this several times and was annoyed 😒 Originally the file wasn't thought to be public API so I didn't put too much thought into the concrete layout, since I thought it would only be read programmatically anyway. I'd be happy to accept a PR, or I can also do it in time for the next release 🙂

[codecholeric]

And yeah, your solution sounds reasonable 👍 Don't see any pitfalls as long as reading the lines again accounts for it (which it might already do anyway 🤷‍♂️)