Get tests passing with frozen-string-literals enabled.

Gemfile

@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 source 'http://rubygems.org'
 
 group :development do
   gem 'rake'
-  gem 'rspec', '~> 3.0'
+  gem 'rspec', '~> 3.7'
 
   # Use same version as Code Climate for consistency with CI
   # https://github.com/codeclimate/codeclimate-rubocop/blob/master/Gemfile.lock

Rakefile

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'bundler'
 require 'rspec/core/rake_task'
 require 'rubocop/rake_task'

lib/websocket.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # WebSocket protocol implementation in Ruby
 # This module does not provide a WebSocket server or client, but is made for using
 # in http servers or clients to provide WebSocket support.

lib/websocket/error.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   class Error < RuntimeError
     class Frame < ::WebSocket::Error

lib/websocket/exception_handler.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module ExceptionHandler
     attr_accessor :error

lib/websocket/frame.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     autoload :Base,     "#{::WebSocket::ROOT}/websocket/frame/base"

lib/websocket/frame/base.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     # @abstract Subclass and override to implement custom frames

lib/websocket/frame/data.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     class Data < String
@@ -11,7 +13,7 @@ def <<(*args)
 
       # Convert all arguments to ASCII-8BIT for easier traversing
       def convert_args(args)
-        args.each { |arg| arg.force_encoding('ASCII-8BIT') }
+        args.collect { |arg| arg.dup.force_encoding('ASCII-8BIT') }
       end
 
       # Extract mask from 4 first bytes according to spec

lib/websocket/frame/handler.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     module Handler

lib/websocket/frame/handler/base.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     module Handler

lib/websocket/frame/handler/handler03.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'securerandom'
 
@@ -89,14 +90,14 @@ def opcode_to_type(opcode)
         def encode_header
           mask = @frame.outgoing_masking? ? 0b10000000 : 0b00000000
 
-          output = ''
+          output = String.new('')
           output << (type_to_opcode(@frame.type) | (fin ? 0b10000000 : 0b00000000)) # since more, rsv1-3 are 0 and 0x80 for Draft 4
           output << encode_payload_length(@frame.data.size, mask)
           output
         end
 
         def encode_payload_length(length, mask)
-          output = ''
+          output = String.new('')
           if length <= 125
             output << (length | mask) # since rsv4 is 0
           elsif length < 65_536 # write 2 byte length
@@ -197,7 +198,7 @@ def decode_payload(payload_length, mask)
         end
 
         def decode_continuation_frame(application_data, frame_type)
-          @application_data_buffer ||= ''
+          @application_data_buffer ||= String.new('')
           @application_data_buffer << application_data
           @frame_type ||= frame_type
         end

lib/websocket/frame/handler/handler04.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 module WebSocket
   module Frame

lib/websocket/frame/handler/handler05.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 module WebSocket
   module Frame

lib/websocket/frame/handler/handler07.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 module WebSocket
   module Frame

lib/websocket/frame/handler/handler75.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 module WebSocket
   module Frame

lib/websocket/frame/incoming.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     # Construct or parse incoming WebSocket Frame.

lib/websocket/frame/incoming/client.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     class Incoming

lib/websocket/frame/incoming/server.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     class Incoming

lib/websocket/frame/outgoing.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     # Construct or parse incoming WebSocket Frame.

lib/websocket/frame/outgoing/client.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     class Outgoing

lib/websocket/frame/outgoing/server.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Frame
     class Outgoing

lib/websocket/handshake.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     autoload :Base,    "#{::WebSocket::ROOT}/websocket/handshake/base"

lib/websocket/handshake/base.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     # @abstract Subclass and override to implement custom handshakes
@@ -16,7 +18,7 @@ def initialize(args = {})
         @state = :new
         @handler = nil
 
-        @data = ''
+        @data = String.new('')
         @headers ||= {}
         @protocols ||= []
       end
@@ -62,7 +64,7 @@ def leftovers
       # @example
       #   @handshake.uri #=> "ws://example.com/path?query=true"
       def uri
-        uri =  secure ? 'wss://' : 'ws://'
+        uri =  String.new(secure ? 'wss://' : 'ws://')
         uri << host
         uri << ":#{port}" if port
         uri << path

lib/websocket/handshake/client.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'uri'
 
 module WebSocket

lib/websocket/handshake/handler.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/base.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/client.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/client01.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'digest/md5'
 
 module WebSocket

lib/websocket/handshake/handler/client04.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'digest/sha1'
 require 'base64'
 

lib/websocket/handshake/handler/client11.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/client75.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/client76.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'digest/md5'
 
 module WebSocket

lib/websocket/handshake/handler/server.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/server04.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'digest/sha1'
 require 'base64'
 

lib/websocket/handshake/handler/server75.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     module Handler

lib/websocket/handshake/handler/server76.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'digest/md5'
 
 module WebSocket

lib/websocket/handshake/server.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module Handshake
     # Construct or parse a server WebSocket handshake.

lib/websocket/nice_inspect.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   module NiceInspect
     # Recreate inspect as #to_s will be overwritten

lib/websocket/version.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WebSocket
   VERSION = '1.2.5'.freeze
 end

spec/frame/incoming_03_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/incoming_04_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/incoming_05_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/incoming_07_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/incoming_75_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/incoming_common_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/masking_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/outgoing_03_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/outgoing_04_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/outgoing_05_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/outgoing_07_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/outgoing_75_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/frame/outgoing_common_spec.rb

@@ -1,4 +1,5 @@
 # encoding: binary
+# frozen_string_literal: true
 
 require 'spec_helper'
 

spec/handshake/client_04_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 RSpec.describe 'Client draft 4 handshake' do

spec/handshake/client_11_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 RSpec.describe 'Client draft 11 handshake' do

spec/handshake/client_75_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 RSpec.describe 'Client draft 75 handshake' do

spec/handshake/client_76_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 RSpec.describe 'Client draft 76 handshake' do