Bisect class to decompose the diff history to be per-file

bisect_test.rb

# Ruby class for automating 'git bisect' with Rails tests
class BisectTest
  def initialize(files_to_test: , last_good_commit: )
    @files_to_test = files_to_test.is_a?(Array) ? files_to_test : [files_to_test]
    @last_good_commit = last_good_commit
  end

  # Function to run the test suite and return true if the test passed, false if it failed
  def test_command
    "bundle exec rails test #{@files_to_test.join(' ')}"
  end

  def run_test(commit)
    results = @files_to_test.map { |file| `git checkout #{commit} && bundle exec rails test #{file}` }
    rr = results.select { |res| res.include?("0 failures, 0 errors") }
    rr.empty? ? nil : rr
  end

  # Start the 'git bisect' process
  def start_bisect
    system("git bisect start")
    system("git bisect bad HEAD")
    system("git bisect good #{@last_good_commit}")
  end

  # Run the 'git bisect' process
  def run_bisect
    start_bisect

    # system("git bisect run") do |commit|
    #   exit 1 if run_test(commit)
    #   exit 0
    # end
    system("git bisect run #{test_command}")
  end

  def create_bisect_prism_branch
    # system("git checkout #{@branch_name} #{@last_good_commit}")
    system("git checkout -b #{bisecting_branch_name}")
  end

  def changed_files
    # `git diff --name-only HEAD #{@last_good_commit}`.split("\n").map(&:strip)
    `git diff --name-only`.split("\n").map(&:strip)
  end

  def bisecting_branch_name(branch_name: @branch_name, prefix: 'bisecting')
    bp = branch_name.split('/')
    bp = bp.size > 1 ? branch_name.tap{|ps| ps[0] = prefix } : bp.unshift(prefix)
    bp.join('/')
  end

  def bisect_prism
    `git reset #{@last_good_commit}`
    create_bisect_prism_branch

    changed_files.map do |file|
      # staged_chunks = `git diff -U0 --staged -- #{file} | grep -e '^\@' | sed 's/^\@.*\\+\([0-9]\\+\\),\\([0-9]\\+\\)/\\1,\\2/'`.split("\n")
      # staged_chunks.each_with_index do |chunk, index|
      puts "🗂️  #{file}"
      end
      [
        `git add #{file}`,
        `git commit -m "git bisect prism: #{file}"`
      ]
    end
  end
end

__END__
# Example usage:
files_to_test = "test/models/files_to_test.rb"
last_good_commit = "abcdef123"  # Replace with a specific commit hash

bisect = BisectTest.new(files_to_test, last_good_commit)
bisect.run_bisect