Get tests passing with frozen-string-literals enabled.

.travis.yml

@@ -7,6 +7,7 @@ rvm:
   - 2.1
   - 2.2
   - 2.3.0
+  - 2.4.1
   - jruby-18mode
   - jruby-19mode
   - jruby-9.0.5.0
@@ -16,6 +17,9 @@ gemfile: ".travis/Gemfile"
 
 sudo: false
 
+before_script:
+- if (ruby -e "exit RUBY_VERSION.to_f >= 2.4"); then export RUBYOPT="--enable-frozen-string-literal"; fi; echo $RUBYOPT
+
 env:
   global:
     - VERBOSE=true

.travis/Gemfile

@@ -9,3 +9,9 @@ when "synchrony"
   gem "hiredis"
   gem "em-synchrony"
 end
+
+if RUBY_VERSION.to_f < 1.9
+  gem 'test-unit', '3.1.5'
+else
+  gem 'test-unit', '>= 3.2.5'
+end

Gemfile

@@ -2,3 +2,9 @@
 source 'https://rubygems.org'
 
 gemspec
+
+if RUBY_VERSION.to_f < 1.9
+  gem 'test-unit', '3.1.5'
+else
+  gem 'test-unit', '>= 3.2.5'
+end

lib/redis/connection/ruby.rb

@@ -39,7 +39,7 @@ def initialize(*args)
         super(*args)
 
         @timeout = @write_timeout = nil
-        @buffer = ""
+        @buffer = "".dup
       end
 
       def timeout=(timeout)

redis.gemspec

@@ -40,5 +40,5 @@ Gem::Specification.new do |s|
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
 
   s.add_development_dependency("rake", "<11.0.0")
-  s.add_development_dependency("test-unit", "3.1.5")
+  s.add_development_dependency("test-unit", ">= 3.1.5")
 end