Add tap file patch diff

[gaborbernat]

Resolves #15838

[MikeMcQuaid]

Thanks for the PR @gaborbernat, much appreciated, looking good so far.

Could you add another test to Library/Homebrew/test/patching_spec.rb so we can see the DSL in action?

[MikeMcQuaid]

Suggested change

	class TapFilePatch < EmbeddedPatch
	def initialize(strip, tap_file)
	super(strip)
	@str = File.open(tap_file).read
	end
	def contents
	@str
	end
	class TapFilePatch < EmbeddedPatch
	attr_reader :contents
	sig { params(strip: T.any(Symbol, String), tap_file: T.any(String, Pathname)).void }
	def initialize(strip, tap_file)
	super(strip)
	@contents = File.open(tap_file).read
	end

Note: I expect that the File.open may need to be a little more involved here to be able to find the patch in a suitable location. The ideal location in a tap would feel like a Patches/ subdirectory in the root. Thoughts?

[gaborbernat]

I personally would prefer to keep the patches alongside the formula in the filesystem/editor... so would prefer not too have a patches folder. Instead Perhaps we can have:

Formula.rb
Formula.patch_name.diff

?

[carlocab]

If that's all you need then you can probably already do something like

patch do
  url "file://#{__dir__}/Formula.patch_name.diff"
end

without having to make any changes to the formula DSL.

[gaborbernat]

Does #{__dir__} gets replaced with the formulas folder name?

[MikeMcQuaid]

yes

[gaborbernat]

Ah then never mind.

[MikeMcQuaid]

Some failing style checks (https://github.com/Homebrew/brew/actions/runs/5788904612/job/15688846613?pr=15841#step:6:12) but brew style --fix should sort these out easily enough.

[gaborbernat]

Could you add another test to Library/Homebrew/test/patching_spec.rb so we can see the DSL in action?

Would love to, but given I have no ruby experience can you point me towards where I can steal it from? 😆

[MikeMcQuaid]

Would love to, but given I have no ruby experience can you point me towards where I can steal it from? 😆

@gaborbernat go in that file, copy-paste an existing test and adjust it to use your new patch method instead of the existing one.