Use frozen string literals throughout the codebase in Ruby >= 2.3

Gemfile

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/adapters.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/adapters/adapter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms
@@ -97,10 +99,11 @@ module Rackstash
       # that ends in a newline character by mutating the object is required.
       #
       # @param line [#to_s] a log line
-      # @return [String] a string with a trailing newline character (`"\n"`)
+      # @return [String] `line` with a trailing newline character (`"\n"`)
+      #   appended if necessary
       def normalize_line(line)
         line = line.to_s
-        line << "\n".freeze unless line.end_with?("\n".freeze)
+        line = "#{line}\n" unless line.end_with?("\n".freeze)
         line
       end
     end

lib/rackstash/adapters/callable.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/adapters/file.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/adapters/io.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/buffer.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/buffer_stack.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/encoders.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/encoders/json.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms
@@ -21,7 +23,7 @@ module Rackstash
       # @param event [Hash] a log event as produced by the {Flow}
       # @return [String] the event as a single-line JSON string
       def encode(event)
-        event[FIELD_MESSAGE].strip!
+        event[FIELD_MESSAGE] = event[FIELD_MESSAGE].strip
         ::JSON.dump(event)
       end
     end

lib/rackstash/encoders/message.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/encoders/raw.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/fields.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/fields/abstract_collection.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms
@@ -156,7 +158,7 @@ module Rackstash
           return utf8_encode(value)
         when Exception
           exception = "#{value.message} (#{value.class})"
-          exception << "\n" << value.backtrace.join("\n") if value.backtrace
+          exception = [exception, *value.backtrace].join("\n") if value.backtrace
           return utf8_encode(exception)
         when ::Proc
           return normalize(value, scope: scope, wrap: wrap)

lib/rackstash/fields/array.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/fields/hash.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/fields/tags.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/flow.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/flows.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/formatter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/logger.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/message.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/sink.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

lib/rackstash/version.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

rackstash.gemspec

@@ -1,4 +1,5 @@
-# coding: utf-8
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/adapters/adapter_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/adapters/callable_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/adapters/file_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/adapters/io_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/adapters_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/buffer_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/buffer_stack_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/encoders/json_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/encoders/message_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/encoders/raw_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/fields/abstract_collection_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms
@@ -63,7 +65,7 @@ describe Rackstash::Fields::AbstractCollection do
 
   describe '#clone' do
     it 'clones the raw value' do
-      raw = 'hello'
+      raw = []
       collection.send(:raw=, raw)
       expect(collection.send(:raw)).to equal raw
 
@@ -71,14 +73,14 @@ describe Rackstash::Fields::AbstractCollection do
       cloned = collection.clone
 
       expect(cloned).not_to equal collection
-      expect(cloned.send(:raw)).to eql 'hello'
+      expect(cloned.send(:raw)).to eql raw
       expect(cloned.send(:raw)).not_to equal raw
     end
   end
 
   describe '#dup' do
     it 'dups the raw value' do
-      raw = 'hello'
+      raw = []
       collection.send(:raw=, raw)
       expect(collection.send(:raw)).to equal raw
 
@@ -86,7 +88,7 @@ describe Rackstash::Fields::AbstractCollection do
       duped = collection.dup
 
       expect(duped).not_to equal collection
-      expect(duped.send(:raw)).to eql 'hello'
+      expect(duped.send(:raw)).to eql raw
       expect(duped.send(:raw)).not_to equal raw
     end
   end

spec/rackstash/fields/array_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/fields/hash_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/fields/tags_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/flows_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/formatter_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/logger_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/message_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms
@@ -108,8 +110,8 @@ describe Rackstash::Message do
   end
 
   describe '#progname' do
-    it 'dups the progname' do
-      progname = 'a message'
+    it 'dup-freezes a mutable progname' do
+      progname = String.new('a message')
       message = Rackstash::Message.new('', progname: progname)
 
       expect(message.progname).to eql progname

spec/rackstash/sink_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash/version_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/rackstash_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms

spec/spec_helper.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright 2017 Holger Just
 #
 # This software may be modified and distributed under the terms