Guardfile
guard "minitest" do
# with Minitest::Spec
watch(%r|^test/(.*)_test\.rb$|)
watch(%r|^app/(.*)/(.*)\.rb$|) { |m| "test/#{m[1]}/#{m[2]}_test.rb" }
watch(%r|^lib/(.*)([^/]+)\.rb$|) { |m| "test/#{m[1]}#{m[2]}_test.rb" }
watch(%r|^test/test_helper\.rb$|) { "test" }
watch(%r|^test/support/|) { "test" }
end