fix: use Redis#exists? for get boolean value

Appraisals

@@ -1,15 +1,7 @@
 if RUBY_VERSION < '2.4'
-  appraise 'rails3.2' do
-    gem 'rails', '~> 3.2.0'
-  end
-
   appraise 'rails4.0' do
     gem 'rails', '~> 4.0.13'
   end
-
-  appraise 'rails4.1' do
-    gem 'rails', '~> 4.1.16'
-  end
 end
 
 appraise 'rails4.2' do

lib/resque/integration/engine.rb

@@ -35,7 +35,7 @@ class Engine < Rails::Engine
     initializer 'resque-integration.redis' do
       redis = Resque.config.redis
 
-      if redis.any?
+      if redis.present?
         Resque.redis = Redis.new(redis)
         Resque.redis.namespace = redis[:namespace] if redis[:namespace]
       end

lib/resque/integration/unique.rb

@@ -165,8 +165,12 @@ def lock_timeout
       end
 
       # Returns true if resque job is in locked state
+      #
+      # Returns Boolean
       def locked?(*args)
-        ::Resque.redis.exists(lock_id(*args))
+        redis = ::Resque.redis
+
+        redis.respond_to?(:exists?) ? redis.exists?(lock_id(*args)) : redis.exists(lock_id(*args))
       end
 
       # Dequeue unique job

resque-integration.gemspec

@@ -28,6 +28,8 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency 'multi_json'
   gem.add_runtime_dependency 'rake'
 
+  gem.add_runtime_dependency 'redis'
+
   gem.add_development_dependency 'bundler'
   gem.add_development_dependency 'rspec', '~> 2.14'
   gem.add_development_dependency 'rspec-its'