ignore をつかって一時ファイルを監視対象から外す from: https://github.com/guard/guard/issues/316?utm_content=bufferc9b58&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer#issuecomment-7609099

Guardfile

# Ignore Vim swap files
ignore /~$/
ignore /^(?:.*[\\\/])?\.[^\\\/]+\.sw[p-z]$/

group :unit do
  guard 'minitest', test_folders: 'test/unit', test_file_patterns: '*_test.rb' do

    watch(%r'^lib/blah/(.+)\.rb$') {|m| "test/unit/#{m[1]}_test.rb"}
    watch(%r'^test/unit/.+_test\.rb$')

  end
end

group :spec do
  guard 'rspec', binstubs: true, spec_paths: ['test/spec'], all_on_start: false, all_after_pass: false do

    watch(%r'^lib/blah/(.+)\.rb$') {|m| "test/spec/#{m[1]}_spec.rb"}
    watch(%r'^test/spec/.+_spec\.rb$')

  end
end