gemspec: Add mocha as a development dependency

Author: avgerin0s

redis.gemspec

@@ -37,6 +37,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = '>= 2.2.2'
 
   s.add_development_dependency("test-unit", ">= 3.1.5")
+  s.add_development_dependency("mocha")
   s.add_development_dependency("hiredis")
   s.add_development_dependency("em-synchrony")
 end

test/helper.rb

@@ -1,4 +1,5 @@
 require "test/unit"
+require "mocha/test_unit"
 require "logger"
 require "stringio"