DRY Guardfile with defined groups for running in focused mode or default mode. Switch at the Guard prompt using scope focus, or scope default.

Guardfile

# Run Guard normally. This Guardfile defines 2 groups:
# 1) default: This is the default group and will run all appropriate specs when anything changes.
# 2) focus: This is the group you want when you are focusing on a specific spec or context of specs. When in this
# scope Guard will only run specs tagged with :focus.
#
# Example:
#  context "GET on :index, /", focus: true do
#    ...
#  end
#
# Change scope at the guard prompt:
# > scope focus
# > scope default

guard 'bundler' do
  watch('Gemfile')
end

# Newer versions of guard-rspec require the actual 'rspec' to be in the CLI
# TODO: Determine the version that switched this command and switch it automatically
# based on version of guard-rspec, appropriately
CLI = 'rspec --format doc'
# If on an older version you may want this one:
#CLI = '--format doc'

def watchers
  watch(%r{^spec/.+_spec\.rb$})
  watch(%r{^lib/(.+)\.rb$})               { |m| "spec/lib/#{m[1]}_spec.rb" }
  watch(%r{spec/support/.+\.rb})          { "spec" }
  watch('spec/spec_helper.rb')            { "spec" }
  watch('config/boot.rb')                 { 'spec' }

  # for Padrino
  watch(%r{^app/controllers/(.+).rb$})    { |m| ["spec/app/controllers/#{m[1]}_controller_spec.rb"] }
  watch(%r{^app/models/(.+).rb$})         { |m| ["spec/app/models/#{m[1]}_spec.rb"] }
  watch(%r{^app/app\.rb$})                { "spec" }
  
  # Factories
  watch(%r{^spec/factories/(.+)\.rb$}) do |m|
    %W[
      spec/models/#{m[1].singularize}_spec.rb
      spec/controllers/#{m[1]}_controller_spec.rb
    ]
  end

  # Rabl templates
  watch(%r{^app/views/(.+)/(.+)\.rabl$}) do |m|
    %W[
      spec/models/#{m[1].singularize}_spec.rb
      spec/controllers/#{m[1]}_controller_spec.rb
    ]
  end

  # Whatever else...
end

def rubocop_watchers
  watch(%r{.+\.rb$})
  watch(%r{.+\.rake$})
  watch(%r{(?:.+/)?\.rubocop\.yml$}) { |m| File.dirname(m[0]) }
end

group :default do
  guard :rspec, :cmd => CLI do
    watchers
  end

  guard :rubocop, cli: ['-D'] do
    rubocop_watchers
  end
  
  guard 'yard', port: '8000', cli: '--plugin activerecord --readme README.md' do
    watch(%r{README.md})
    watch(%r{app/.+\.rb})
    watch(%r{lib/.+\.rb})
    watch(%r{ext/.+\.c})
  end
end

group :focus do
  guard :rspec, :cmd => "#{CLI} --tag focus" do
    watchers
  end
end

scope group: :default

At the Guard prompt, run

scope focus

to switch to focus mode, and:

scope default

to switch back to default mode.