Ruby Flog Flay Setup

Overview

Install flog/flay Rake tasks with env-configurable thresholds and a pre-commit hook that runs bundle exec rake.

Workflow

1) Inspect existing setup

• Check Gemfile for flog and flay entries.
• Search for existing :flog or :flay rake tasks in Rakefile and rakelib/ to avoid duplicates.
• Check git config core.hooksPath to determine the hooks directory (default is .git/hooks when unset).

2) Ensure dependencies

• Add gem "flay" and gem "flog" to Gemfile if missing (no version pinning).
• Run bundle install if needed.

3) Define tasks in Rakefile

• Define :flog and :flay tasks directly in Rakefile.
• Use env-configurable thresholds with defaults.
• Use bundle exec for both tools.
• Log only on failure using puts and exit non-zero; stay silent on success.
• Do not filter out any files or paths.
• Allow flay duplication when Total score <= FLAY_THRESHOLD.

Example task definitions:

desc "Run flog"
task :flog do
  output = `bundle exec flog -a lib`
  threshold = (ENV["FLOG_THRESHOLD"] || 25).to_i
  method_scores = []

  output.each_line do |line|
    if line =~ /^\s*(\d+\.\d+):\s+(.+#.+)\s+(.+\.rb)/
      score = $1.to_f
      method_name = $2.strip
      file_path = $3.strip
      method_scores << [score, "#{method_name} #{file_path}"]
    end
  end

  failing_methods = method_scores.select { |score, _| score > threshold }
  if failing_methods.any?
    puts "\nFlog failed: Methods with complexity score > #{threshold}:"
    failing_methods.each { |score, method_name| puts "  #{score}: #{method_name}" }
    exit 1
  end
end

desc "Run flay"
task :flay do
  output = `bundle exec flay lib`
  threshold = (ENV["FLAY_THRESHOLD"] || 0).to_i

  if (match = output.match(/Total score \(lower is better\) = (\d+)/))
    score = match[1].to_i
    if score > threshold
      puts "\nFlay failed: Total duplication score is #{score}, must be <= #{threshold}"
      puts output
      exit 1
    end
  end
end

• Remove or update any conflicting :flog/:flay tasks in rakelib/ to avoid duplicate definitions.
• Ensure the default task includes flog and flay if the project expects them to run in CI.

4) Install pre-commit hook

• Create or update pre-commit in the hooks directory from core.hooksPath (or .git/hooks).
• Use bash and run bundle exec rake unconditionally.
• Exit non-zero if rake fails.

Example hook:

#!/usr/bin/env bash
bundle exec rake
result=$?
if [ $result -ne 0 ]; then
  echo "bundle exec rake failed. Commit aborted."
  exit $result
fi

• Ensure the hook is executable.

5) Verify

• Run bundle exec rake and confirm it succeeds.
• Make a test commit if needed to confirm the hook blocks failing builds.