Fix Cask artifact rename operation on Linux by making xattr metadata no-op

Co-authored-by: MikeMcQuaid <125011+MikeMcQuaid@users.noreply.github.com>

Library/Homebrew/cask/artifact/relocated.rb

@@ -79,8 +79,9 @@ module Cask
       # Try to make the asset searchable under the target name. Spotlight
       # respects this attribute for many filetypes, but ignores it for App
       # bundles. Alfred 2.2 respects it even for App bundles.
-      def add_altname_metadata(file, altname, command: nil)
+      sig { params(file: Pathname, altname: Pathname, command: T.class_of(SystemCommand)).returns(T.nilable(SystemCommand::Result)) }
-        return if altname.to_s.casecmp(file.basename.to_s).zero?
+      def add_altname_metadata(file, altname, command:)
+        return if altname.to_s.casecmp(file.basename.to_s)&.zero?
 
         odebug "Adding #{ALT_NAME_ATTRIBUTE} metadata"
         altnames = command.run("/usr/bin/xattr",
@@ -108,3 +109,5 @@ module Cask
     end
   end
 end
+
+require "extend/os/cask/artifact/relocated"

Library/Homebrew/extend/os/cask/artifact/relocated.rb

@@ -0,0 +1,4 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "extend/os/linux/cask/artifact/relocated" if OS.linux?

Library/Homebrew/extend/os/linux/cask/artifact/relocated.rb

@@ -0,0 +1,23 @@
+# typed: strict
+# frozen_string_literal: true
+
+module OS
+  module Linux
+    module Cask
+      module Artifact
+        module Relocated
+          extend T::Helpers
+
+          requires_ancestor { ::Cask::Artifact::Relocated }
+
+          sig { params(file: Pathname, altname: Pathname, command: T.class_of(SystemCommand)).returns(T.nilable(SystemCommand::Result)) }
+          def add_altname_metadata(file, altname, command:)
+            # no-op on Linux: /usr/bin/xattr for setting extended attributes is not available there.
+          end
+        end
+      end
+    end
+  end
+end
+
+Cask::Artifact::Relocated.prepend(OS::Linux::Cask::Artifact::Relocated)

Library/Homebrew/test/cask/artifact/relocated_spec.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require "cask/artifact/relocated"
+
+RSpec.describe Cask::Artifact::Relocated, :cask do
+  let(:cask) do
+    Cask::Cask.new("test-cask") do
+      url "file://#{TEST_FIXTURE_DIR}/cask/caffeine.zip"
+      homepage "https://brew.sh/"
+      version "1.0"
+      sha256 "67cdb8a02803ef37fdbf7e0be205863172e41a561ca446cd84f0d7ab35a99d94"
+    end
+  end
+
+  let(:command) { NeverSudoSystemCommand }
+  let(:artifact) { described_class.new(cask, "test_file.txt") }
+
+  describe "#add_altname_metadata" do
+    let(:file) { Pathname("/tmp/test_file.txt") }
+    let(:altname) { Pathname("alternate_name.txt") }
+
+    before do
+      allow(file).to receive_messages(basename: Pathname("test_file.txt"), writable?: true, realpath: file)
+    end
+
+    context "when running on Linux", :needs_linux do
+      it "is a no-op and does not call xattr commands" do
+        expect(command).not_to receive(:run)
+        expect(command).not_to receive(:run!)
+
+        artifact.send(:add_altname_metadata, file, altname, command: command)
+      end
+    end
+
+    context "when running on macOS", :needs_macos do
+      before do
+        stdout_double = instance_double(SystemCommand::Result, stdout: "")
+        allow(command).to receive(:run).and_return(stdout_double)
+        allow(command).to receive(:run!)
+      end
+
+      it "calls xattr commands to set metadata" do
+        expect(command).to receive(:run).with("/usr/bin/xattr",
+                                              args:         ["-p", "com.apple.metadata:kMDItemAlternateNames", file],
+                                              print_stderr: false)
+        expect(command).to receive(:run!).twice
+
+        artifact.send(:add_altname_metadata, file, altname, command: command)
+      end
+    end
+  end
+end