utils: add `git_repository`

Library/Homebrew/.rubocop_todo.yml

@@ -20,6 +20,7 @@ Style/Documentation:
     - 'utils.rb'
     - 'utils/fork.rb'
     - 'utils/gems.rb'
+    - 'utils/git_repository.rb'
     - 'utils/popen.rb'
     - 'utils/shell.rb'
     - 'version.rb'

Library/Homebrew/extend/git_repository.rb

@@ -40,11 +40,12 @@ module GitRepositoryExtension
   end
 
   # Gets a short commit hash of the HEAD commit.
-  sig { returns(T.nilable(String)) }
-  def git_short_head
+  sig { params(length: T.nilable(Integer)).returns(T.nilable(String)) }
+  def git_short_head(length: 4)
     return unless git? && Utils::Git.available?
 
-    Utils.popen_read("git", "rev-parse", "--short=4", "--verify", "-q", "HEAD", chdir: self).chomp.presence
+    Utils.popen_read("git", "rev-parse", "--short#{length&.to_s&.prepend("=")}",
+                     "--verify", "-q", "HEAD", chdir: self).chomp.presence
   end
 
   # Gets the relative date of the last commit, e.g. "1 hour ago"

Library/Homebrew/test/utils/git_repository_spec.rb

+# typed: false
+# frozen_string_literal: true
+
+require "utils/git_repository"
+
+describe Utils do
+  before do
+    HOMEBREW_CACHE.cd do
+      system "git", "init"
+      Pathname("README.md").write("README")
+      system "git", "add", "README.md"
+      system "git", "commit", "-m", "File added"
+    end
+  end
+
+  let(:head_revision) { HOMEBREW_CACHE.cd { `git rev-parse HEAD`.chomp } }
+  let(:short_head_revision) { HOMEBREW_CACHE.cd { `git rev-parse --short HEAD`.chomp } }
+
+  describe ".git_head" do
+    it "returns the revision at HEAD" do
+      expect(described_class.git_head(HOMEBREW_CACHE)).to eq(head_revision)
+      expect(described_class.git_head(HOMEBREW_CACHE, length: 5)).to eq(head_revision[0...5])
+    end
+  end
+
+  describe ".git_short_head" do
+    it "returns the short revision at HEAD" do
+      expect(described_class.git_short_head(HOMEBREW_CACHE)).to eq(short_head_revision)
+      expect(described_class.git_short_head(HOMEBREW_CACHE, length: 5)).to eq(head_revision[0...5])
+    end
+  end
+end

Library/Homebrew/utils.rb

@@ -7,6 +7,7 @@ require "utils/fork"
 require "utils/formatter"
 require "utils/gems"
 require "utils/git"
+require "utils/git_repository"
 require "utils/github"
 require "utils/inreplace"
 require "utils/link"

Library/Homebrew/utils/git_repository.rb

+# typed: strict
+# frozen_string_literal: true
+
+module Utils
+  extend T::Sig
+
+  sig { params(repo: T.any(String, Pathname), length: T.nilable(Integer)).returns(T.nilable(String)) }
+  def self.git_head(repo, length: nil)
+    return git_short_head(repo, length: length) if length.present?
+
+    repo = Pathname(repo).extend(GitRepositoryExtension)
+    repo.git_head
+  end
+
+  sig { params(repo: T.any(String, Pathname), length: T.nilable(Integer)).returns(T.nilable(String)) }
+  def self.git_short_head(repo, length: nil)
+    repo = Pathname(repo).extend(GitRepositoryExtension)
+    repo.git_short_head(length: length)
+  end
+end