update: Don't report formulae that are moved within a tap but not renamed

[jawshooah]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew tests with your changes locally?

---

It's misleading to report a formula as "new" when it's only been moved from one directory to another within the same tap.

Ref: caskroom/homebrew-cask#22669 (comment)

[UniqMartin]

There's a very subtle problem with these two lines. If formulae happen to be moved within a tap and a formula gets renamed before or afterwards (thus src_full_name != dst_full_name) and the update covers both operations, then the report will look something like this (I experimented a bit with my local copy of the homebrew/gui tap):

Updated 1 tap (homebrew/gui).
==> New Formulae
homebrew/gui/xchat2

But it should have looked something like this:

Updated 1 tap (homebrew/gui).
==> Renamed Formulae
homebrew/gui/xchat -> homebrew/gui/xchat2

The reason is that if tap.formula_file?(src) will always be false as it checks against the current Tap#formula_dir. It's admittedly a rare corner case, but this should solve it:

if tap.formula_file?(dst)
  @report[:D] << src_full_name
  @report[:A] << dst_full_name
end

[jawshooah]

Nice catch! Fixed in f1a7eb6

[UniqMartin]

Thanks for finding an even more elegant solution and particularly for adding a nice test case!

[UniqMartin]

Thanks for taking a look and for this PR! I commented on a corner case, but otherwise it's looking good.

Unfortunately, other parts of Homebrew also assume that Tap#formula_dir never changes during the lifetime of a tap and thus break if formulae are relocated within a tap. See issue #87 for details. Do you maybe see yourself tackling these as well? (Would be awesome, but I certainly don't expect you to.)

[UniqMartin]

I just realized this check can be dropped completely, as there's a check preceding the case statement that already makes sure that at least one of the modified paths is a formula file:

next unless paths.any? { |p| tap.formula_file?(p) }

[jawshooah]

Got it, removed in 7195878.

[UniqMartin]

Merged in 4abdeb7. Thank you for this contribution to Homebrew, @jawshooah! 🎉

Sorry for the long delay! I'd be still interested in your answer to the following question:

Unfortunately, other parts of Homebrew also assume that Tap#formula_dir never changes during the lifetime of a tap and thus break if formulae are relocated within a tap. See issue #87 for details. Do you maybe see yourself tackling these as well?

[jawshooah]

@UniqMartin No worries! Sorry for the delay in getting back to you. I haven't looked too deeply into FormulaVersions but it seems like a proper fix might require a deep dive into Git plumbing commands. I'll see about giving it a shot later this evening, but I can't make any promises.