diff --git a/Gemfile b/Gemfile
index fd799238..723e6108 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ gemspec
 gem 'gettext', '>= 3.1.3', '< 4.0.0'
 
 group :test do
-  gem 'rake', '~> 10.1.0'
+  gem 'rake'
   gem 'thor'
   gem 'minitest', '4.7.4'
   gem 'minitest-spec-context'
diff --git a/Rakefile b/Rakefile
index b5a45a5b..7d88e9bd 100644
--- a/Rakefile
+++ b/Rakefile
@@ -11,6 +11,7 @@ Rake::TestTask.new do |t|
   t.libs.push "lib"
   t.test_files = Dir.glob('test/**/*_test.rb')
   t.verbose = true
+  t.warning = false unless ENV['RUBY_WARNINGS']
 end
 
 file "man/hammer.1.gz" => "man/hammer.1.asciidoc" do |t|
diff --git a/hammer_cli.gemspec b/hammer_cli.gemspec
index 5194f8fd..08d225e8 100644
--- a/hammer_cli.gemspec
+++ b/hammer_cli.gemspec
@@ -27,7 +27,7 @@ EOF
   s.require_paths = ["lib"]
   s.executables = ['hammer', 'hammer-complete']
 
-  s.add_dependency 'clamp', '>= 1.1', '< 1.2.0'
+  s.add_dependency 'clamp', '>= 1.1', '< 2.0.0'
   s.add_dependency 'logging'
   s.add_dependency 'unicode-display_width'
   s.add_dependency 'unicode'
diff --git a/lib/hammer_cli/abstract.rb b/lib/hammer_cli/abstract.rb
index 200410c3..877838fc 100644
--- a/lib/hammer_cli/abstract.rb
+++ b/lib/hammer_cli/abstract.rb
@@ -42,7 +42,7 @@ def help_extension_blocks
       end
 
       def command_extensions
-        @command_extensions = @command_extensions || inherited_command_extensions || []
+        @command_extensions ||= inherited_command_extensions || []
         @command_extensions
       end
 
@@ -192,7 +192,7 @@ def self.extend_output_definition(&block)
 
     def self.output(definition=nil, &block)
       dsl = HammerCLI::Output::Dsl.new
-      dsl.build &block if block_given?
+      dsl.build(&block) if block_given?
       output_definition.append definition.fields unless definition.nil?
       output_definition.append dsl.fields
     end
@@ -206,7 +206,7 @@ def output_definition
     end
 
     def self.output_definition
-      @output_definition = @output_definition || inherited_output_definition || HammerCLI::Output::Definition.new
+      @output_definition ||= inherited_output_definition || HammerCLI::Output::Definition.new
       @output_definition
     end
 
@@ -341,27 +341,27 @@ def exception_handler_class
     end
 
     def self.desc(desc=nil)
-      @desc = desc if desc
-      @desc
+      return @desc ||= nil unless desc
+
+      @desc = desc
     end
 
     def self.command_name(name=nil)
-      if @names && name
-        @names << name if !@names.include?(name)
-      else
-        @names = [name] if name
-      end
-      @names || (superclass.respond_to?(:command_names) ? superclass.command_names : nil)
+      command_names(name)
     end
 
     def self.command_names(*names)
-      @names = names unless names.empty?
-      @names || (superclass.respond_to?(:command_names) ? superclass.command_names : nil)
+      names = names.compact
+      return @names ||= (superclass.respond_to?(:command_names) ? superclass.command_names : nil) if names.empty?
+
+      @names ||= []
+      @names |= names
     end
 
     def self.warning(message = nil)
-      @warning_msg = message if message
-      @warning_msg
+      return @warning_msg ||= nil unless message
+
+      @warning_msg = message
     end
 
     def self.autoload_subcommands
diff --git a/lib/hammer_cli/apipie/resource.rb b/lib/hammer_cli/apipie/resource.rb
index 01e4a0da..57cd4427 100644
--- a/lib/hammer_cli/apipie/resource.rb
+++ b/lib/hammer_cli/apipie/resource.rb
@@ -37,7 +37,7 @@ def connection_name(resource_class)
       end
 
       def class_resource
-        return @api_resource if @api_resource
+        return @api_resource if @api_resource ||= nil
         return superclass.class_resource if superclass.respond_to? :class_resource
       end
 
@@ -68,7 +68,7 @@ def resource(resource=nil, action=nil)
 
       def action(action=nil)
         @api_action = action unless action.nil?
-        return @api_action if @api_action
+        return @api_action if @api_action ||= nil
         return superclass.action if superclass.respond_to? :action
       end
 
diff --git a/lib/hammer_cli/command_extensions.rb b/lib/hammer_cli/command_extensions.rb
index 03cd01a9..e26e8919 100644
--- a/lib/hammer_cli/command_extensions.rb
+++ b/lib/hammer_cli/command_extensions.rb
@@ -33,7 +33,7 @@ def inheritable?
     end
 
     def self.method_missing(message, *args, &block)
-      if @delegatee
+      if @delegatee ||= nil
         @delegatee.send(message, *args, &block)
       else
         super
@@ -121,7 +121,7 @@ def extend_output
       allowed = @only & %i[output]
       return if allowed.empty? || (allowed & @except).any?
 
-      self.class.extend_output(@command_class, @command_object)
+      self.class.extend_output(@command_class, @command_object ||= nil)
     end
 
     def extend_help
@@ -205,6 +205,7 @@ def self.extend_options(command_class)
     end
 
     def self.extend_predefined_options(command_class)
+      @predefined_option_names ||= nil
       command_class.send(:use_option, *@predefined_option_names)
       logger.debug("Added predefined options for #{command_class}: #{@predefined_option_names}")
     end
@@ -259,9 +260,7 @@ def self.extend_option_sources(sources, command_object, command_class)
     end
 
     def self.extend_option_family(command_class)
-      return if @option_family_extensions.nil?
-
-      @option_family_extensions.each do |extension|
+      (@option_family_extensions ||= []).each do |extension|
         extension[:options][:creator] = command_class
         command_class.send(:option_family, extension[:options], &extension[:block])
         logger.debug("Called option family block for #{command_class}:\n\t#{extension[:block]}")
diff --git a/lib/hammer_cli/defaults_commands.rb b/lib/hammer_cli/defaults_commands.rb
index cff5bf66..74df19b1 100644
--- a/lib/hammer_cli/defaults_commands.rb
+++ b/lib/hammer_cli/defaults_commands.rb
@@ -1,4 +1,3 @@
-require 'hammer_cli'
 require 'yaml'
 module HammerCLI
   class BaseDefaultsProvider
diff --git a/lib/hammer_cli/help/builder.rb b/lib/hammer_cli/help/builder.rb
index 544acd41..dbe9edc3 100644
--- a/lib/hammer_cli/help/builder.rb
+++ b/lib/hammer_cli/help/builder.rb
@@ -14,7 +14,7 @@ def initialize(richtext = false)
       def add_usage(invocation_path, usage_descriptions)
         heading(Clamp.message(:usage_heading))
         usage_descriptions.each do |usage|
-          puts "    #{HammerCLI.expand_invocation_path(invocation_path)} #{usage}".rstrip
+          line "    #{HammerCLI.expand_invocation_path(invocation_path)} #{usage}".rstrip
         end
       end
 
@@ -24,7 +24,7 @@ def add_list(heading, items)
         end
         items.reject! {|item| item.respond_to?(:hidden?) && item.hidden?}
 
-        puts
+        line
         heading(heading)
 
         label_width = DEFAULT_LABEL_INDENT
@@ -47,15 +47,15 @@ def add_list(heading, items)
                                  item.help
                                end
           description.gsub(/^(.)/) { Unicode.capitalize(Regexp.last_match(1)) }.wrap.each_line do |line|
-            puts " %-#{label_width}s %s" % [label, line]
+            line " %-#{label_width}s %s" % [label, line]
             label = ''
           end
         end
       end
 
       def add_text(content)
-        puts
-        puts content
+        line
+        line content
       end
 
       protected
@@ -63,7 +63,7 @@ def add_text(content)
       def heading(label)
         label = "#{label}:"
         label = HighLine.color(label, :bold) if @richtext
-        puts label
+        line label
       end
     end
   end
diff --git a/lib/hammer_cli/logger.rb b/lib/hammer_cli/logger.rb
index b6dc66a4..af7f459b 100644
--- a/lib/hammer_cli/logger.rb
+++ b/lib/hammer_cli/logger.rb
@@ -54,7 +54,7 @@ def self.initialize_logger(logger)
       log_dir = File.expand_path(HammerCLI::Settings.get(:log_dir) || DEFAULT_LOG_DIR)
       begin
         FileUtils.mkdir_p(log_dir, :mode => 0750)
-      rescue Errno::EACCES => e
+      rescue Errno::EACCES => _
         $stderr.puts _("No permissions to create log dir %s.") % log_dir
       end
 
@@ -68,7 +68,7 @@ def self.initialize_logger(logger)
                                                             :size     => (HammerCLI::Settings.get(:log_size) || 1)*1024*1024) # 1MB
         # set owner and group (it's ignored if attribute is nil)
         FileUtils.chown HammerCLI::Settings.get(:log_owner), HammerCLI::Settings.get(:log_group), filename
-      rescue ArgumentError => e
+      rescue ArgumentError => _
         $stderr.puts _("File %s not writeable, won't log anything to the file!") % filename
       end
 
diff --git a/lib/hammer_cli/modules.rb b/lib/hammer_cli/modules.rb
index 62465091..f5d6f8c8 100644
--- a/lib/hammer_cli/modules.rb
+++ b/lib/hammer_cli/modules.rb
@@ -67,7 +67,7 @@ def self.load!(name)
 
     def self.load(name)
       load! name
-    rescue Exception => e
+    rescue Exception => _
       false
     end
 
diff --git a/lib/hammer_cli/options/normalizers.rb b/lib/hammer_cli/options/normalizers.rb
index 70e795fc..9b498d97 100644
--- a/lib/hammer_cli/options/normalizers.rb
+++ b/lib/hammer_cli/options/normalizers.rb
@@ -298,7 +298,7 @@ def format(val)
           json_string = ::File.exist?(::File.expand_path(val)) ? super(val) : val
           ::JSON.parse(json_string)
 
-        rescue ::JSON::ParserError => e
+        rescue ::JSON::ParserError => _
           raise ArgumentError, _("Unable to parse JSON input.")
         end
 
diff --git a/lib/hammer_cli/options/option_family.rb b/lib/hammer_cli/options/option_family.rb
index 4f9f0993..17ff3b4b 100644
--- a/lib/hammer_cli/options/option_family.rb
+++ b/lib/hammer_cli/options/option_family.rb
@@ -19,6 +19,7 @@ def initialize(options = {})
         @children = []
         @options = options
         @creator = options[:creator] || self
+        @parent = nil
         @prefix = options[:prefix]
         @root = options[:root] || options[:aliased_resource] || options[:referenced_resource]
         @creator.family_registry.register(self) if @creator != self
diff --git a/lib/hammer_cli/options/validators/dsl.rb b/lib/hammer_cli/options/validators/dsl.rb
index eb4f6971..8c25d2d7 100644
--- a/lib/hammer_cli/options/validators/dsl.rb
+++ b/lib/hammer_cli/options/validators/dsl.rb
@@ -152,7 +152,7 @@ def one_of(*to_check)
         end
 
         def run(&block)
-          self.instance_eval &block
+          self.instance_eval(&block)
         end
       end
     end
diff --git a/lib/hammer_cli/output/adapter/csv.rb b/lib/hammer_cli/output/adapter/csv.rb
index 26f5269e..d6fadbc7 100644
--- a/lib/hammer_cli/output/adapter/csv.rb
+++ b/lib/hammer_cli/output/adapter/csv.rb
@@ -94,7 +94,6 @@ def initialize(field)
         @name = nil
         @prefixes = []
         @suffixes = []
-        @data
       end
 
       def append_suffix(suffix)
diff --git a/lib/hammer_cli/output/dsl.rb b/lib/hammer_cli/output/dsl.rb
index 1606e930..bc8ad225 100644
--- a/lib/hammer_cli/output/dsl.rb
+++ b/lib/hammer_cli/output/dsl.rb
@@ -12,7 +12,7 @@ def fields
     end
 
     def build(&block)
-      self.instance_eval &block
+      self.instance_eval(&block)
     end
 
     protected
diff --git a/lib/hammer_cli/output/fields.rb b/lib/hammer_cli/output/fields.rb
index 98671ab6..44bb0fdb 100644
--- a/lib/hammer_cli/output/fields.rb
+++ b/lib/hammer_cli/output/fields.rb
@@ -13,6 +13,7 @@ def initialize(options={})
       @label = options[:label]
       @sets = options[:sets]
       @options = options
+      @parent = nil
     end
 
     def id
@@ -57,8 +58,7 @@ def parameters
     protected
 
     def inherited_sets
-      return nil if @parent.nil?
-      @parent.sets
+      @parent&.sets
     end
 
     def default_sets
@@ -72,7 +72,7 @@ class ContainerField < Field
     def initialize(options={}, &block)
       super(options)
       dsl = HammerCLI::Output::Dsl.new
-      dsl.build &block if block_given?
+      dsl.build(&block) if block_given?
       dsl.fields.each { |f| f.parent = self }
       self.output_definition.append dsl.fields
     end
diff --git a/lib/hammer_cli/output/formatters.rb b/lib/hammer_cli/output/formatters.rb
index 5b659d9e..40915d6f 100644
--- a/lib/hammer_cli/output/formatters.rb
+++ b/lib/hammer_cli/output/formatters.rb
@@ -13,7 +13,7 @@ def initialize(formatter_map={})
 
       def register_formatter(type, *formatters)
         if @_formatters[type].nil?
-          @_formatters[type] = FormatterContainer.new *formatters
+          @_formatters[type] = FormatterContainer.new(*formatters)
         else
           formatters.each { |f| @_formatters[type].add_formatter(f) }
         end
@@ -84,8 +84,8 @@ def required_features
         tags.map { |t| HammerCLI::Output::Utils.tag_to_feature(t) }
       end
 
-      def format(data, field_params={})
-        c = HighLine.color(data.to_s, @color)
+      def format(data, _={})
+        HighLine.color(data.to_s, @color)
       end
     end
 
@@ -97,7 +97,7 @@ def required_features
         tags.map { |t| HammerCLI::Output::Utils.tag_to_feature(t) }
       end
 
-      def format(string_date, field_params={})
+      def format(string_date, _={})
         t = DateTime.parse(string_date.to_s)
         t.strftime("%Y/%m/%d %H:%M:%S")
       rescue ArgumentError
diff --git a/lib/hammer_cli/output/record_collection.rb b/lib/hammer_cli/output/record_collection.rb
index e3396edc..757165d5 100644
--- a/lib/hammer_cli/output/record_collection.rb
+++ b/lib/hammer_cli/output/record_collection.rb
@@ -6,10 +6,10 @@ class MetaData
     attr_accessor :total, :subtotal, :page, :per_page, :search, :sort_by, :sort_order, :pagination_verbosity
 
     def initialize(options={})
-      @total = options[:total].to_i if options[:total]
-      @subtotal = options[:subtotal].to_i if options[:subtotal]
-      @page = options[:page].to_i if options[:page]
-      @per_page = options[:per_page].to_i if options[:per_page]
+      @total = options[:total]&.to_i
+      @subtotal = options[:subtotal]&.to_i
+      @page = options[:page]&.to_i
+      @per_page = options[:per_page]&.to_i
       @search = options[:search]
       @sort_by = options[:sort_by]
       @sort_order = options[:sort_order]
diff --git a/lib/hammer_cli/ssloptions.rb b/lib/hammer_cli/ssloptions.rb
index bf0fad60..8799f0dc 100644
--- a/lib/hammer_cli/ssloptions.rb
+++ b/lib/hammer_cli/ssloptions.rb
@@ -68,13 +68,13 @@ def cert_key_options
 
     def read_certificate(path)
       OpenSSL::X509::Certificate.new(File.read(path)) unless path.nil?
-    rescue SystemCallError => e
+    rescue SystemCallError => _
       warn _("Could't read SSL client certificate %s.") % path
     end
 
     def read_key(path)
       OpenSSL::PKey.read(File.read(path)) unless path.nil?
-    rescue SystemCallError => e
+    rescue SystemCallError => _
       warn _("Could't read SSL client key %s.") % path
     end
   end
diff --git a/lib/hammer_cli/subcommand.rb b/lib/hammer_cli/subcommand.rb
index 9598bb8a..85b47a22 100644
--- a/lib/hammer_cli/subcommand.rb
+++ b/lib/hammer_cli/subcommand.rb
@@ -11,6 +11,7 @@ def initialize(names, description, subcommand_class, options = {})
         @subcommand_class = subcommand_class
         @hidden = options[:hidden]
         @warning = options[:warning]
+        super(@names, @description, @subcommand_class)
       end
 
       def hidden?
diff --git a/lib/hammer_cli/testing/command_assertions.rb b/lib/hammer_cli/testing/command_assertions.rb
index 10089e33..40d74002 100644
--- a/lib/hammer_cli/testing/command_assertions.rb
+++ b/lib/hammer_cli/testing/command_assertions.rb
@@ -35,7 +35,7 @@ def run_cmd(options, context={}, cmd_class=HammerCLI::MainCommand)
       end
 
       def exit_code_map
-        return @exit_code_map unless @exit_code_map.nil?
+        return @exit_code_map if @exit_code_map ||= nil
 
         hammer_exit_codes = HammerCLI.constants.select{|c| c.to_s.start_with?('EX_')}
         @exit_code_map = hammer_exit_codes.inject({}) do |code_map, code|
diff --git a/lib/hammer_cli/utils.rb b/lib/hammer_cli/utils.rb
index bd40112a..dcb94010 100644
--- a/lib/hammer_cli/utils.rb
+++ b/lib/hammer_cli/utils.rb
@@ -48,18 +48,6 @@ def wrap(line_width: 80, break_sequence: "\n")
   end
 end
 
-class Hash
-  # for ruby < 2.5.0
-  def transform_keys
-    result = {}
-    each do |key, value|
-      new_key = yield key
-      result[new_key] = value
-    end
-    result
-  end
-end
-
 module HammerCLI
 
   def self.tty?
diff --git a/test/functional/defaults_test.rb b/test/functional/defaults_test.rb
index bf90353b..d5b046bf 100644
--- a/test/functional/defaults_test.rb
+++ b/test/functional/defaults_test.rb
@@ -24,7 +24,6 @@ def self.get_defaults(param)
     let(:cmd) { ['defaults', 'list'] }
 
     it 'prints all defaults' do
-      header = 'Parameter,Value'
       default_values = {
         :organization_id => {
           :value => 3,
diff --git a/test/unit/apipie/command_test.rb b/test/unit/apipie/command_test.rb
index 10a2eb0c..c0ceab24 100644
--- a/test/unit/apipie/command_test.rb
+++ b/test/unit/apipie/command_test.rb
@@ -42,7 +42,7 @@ class CommandUnsupp < HammerCLI::Apipie::Command
     let(:cmd_class) { CommandUnsupp.dup }
     let(:cmd) { cmd_class.new("unsupported", ctx) }
     it "should print help for unsupported command" do
-      assert_match /.*Unfortunately the server does not support such operation.*/, cmd.help
+      assert_match(/.*Unfortunately the server does not support such operation.*/, cmd.help)
     end
 
   end
diff --git a/test/unit/apipie/option_definition_test.rb b/test/unit/apipie/option_definition_test.rb
index 5ce02264..2c614bf8 100644
--- a/test/unit/apipie/option_definition_test.rb
+++ b/test/unit/apipie/option_definition_test.rb
@@ -4,7 +4,7 @@
 
 describe HammerCLI::Apipie::OptionDefinition do
 
-  let(:opt) { HammerCLI::Apipie::OptionDefinition.new("--opt", "OPT", "", :referenced_resource => @referenced_resource) }
+  let(:opt) { HammerCLI::Apipie::OptionDefinition.new("--opt", "OPT", "", :referenced_resource => @referenced_resource ||= nil) }
 
   describe "referenced resource" do
     it "should be nil by default" do
@@ -23,7 +23,7 @@
 
   end
 
-  let(:opt2) { HammerCLI::Apipie::OptionDefinition.new("--opt2", "OPT2", "&#39;OPT2&#39;", :referenced_resource => @referenced_resource) }
+  let(:opt2) { HammerCLI::Apipie::OptionDefinition.new("--opt2", "OPT2", "&#39;OPT2&#39;") }
 
   describe "Option Description should be converted" do
     it "should be converted" do
diff --git a/test/unit/exception_handler_test.rb b/test/unit/exception_handler_test.rb
index c6a55ee8..87e9843e 100644
--- a/test/unit/exception_handler_test.rb
+++ b/test/unit/exception_handler_test.rb
@@ -30,7 +30,7 @@
   end
 
   it "should handle help request" do
-    output.expects(:print_message).with(cmd.help, {}, verbosity: HammerCLI::V_QUIET)
+    output.expects(:print_message).with(cmd.help, {}, { verbosity: HammerCLI::V_QUIET })
     handler.handle_exception(Clamp::HelpWanted.new(cmd), :heading => heading)
 
   end
@@ -51,8 +51,8 @@
     ex = RestClient::ResourceNotFound.new
     output.default_adapter = :silent
     handler.handle_exception(ex)
-    assert_match /Using exception handler HammerCLI::ExceptionHandler#handle_not_found/, @log_output.readline.strip
-    assert_match /ERROR  Exception : (Resource )?Not Found/, @log_output.readline.strip
+    assert_match(/Using exception handler HammerCLI::ExceptionHandler#handle_not_found/, @log_output.readline.strip)
+    assert_match(/ERROR  Exception : (Resource )?Not Found/, @log_output.readline.strip)
   end
 
   it "should print default prompts for standard missing arguments" do
diff --git a/test/unit/history_test.rb b/test/unit/history_test.rb
index ce22d4fb..5a3aa5e9 100644
--- a/test/unit/history_test.rb
+++ b/test/unit/history_test.rb
@@ -20,13 +20,13 @@
   describe "loading old history" do
 
     it "skips loading if the file does not exist" do
-      history = HammerCLI::ShellHistory.new(new_file.path)
+      HammerCLI::ShellHistory.new(new_file.path)
 
       Readline::HISTORY.to_a.must_equal []
     end
 
     it "preseeds readline's history" do
-      history = HammerCLI::ShellHistory.new(history_file.path)
+      HammerCLI::ShellHistory.new(history_file.path)
 
       Readline::HISTORY.to_a.must_equal ["line 1", "line 2"]
     end
diff --git a/test/unit/logger_test.rb b/test/unit/logger_test.rb
index 8dff9d15..9385fb66 100644
--- a/test/unit/logger_test.rb
+++ b/test/unit/logger_test.rb
@@ -12,7 +12,7 @@
 
         HammerCLI::Settings.load({:log_dir => log_dir})
 
-        out, err = capture_io do
+        _, err = capture_io do
           HammerCLI::Logger::initialize_logger(logger)
         end
 
diff --git a/test/unit/options/option_definition_test.rb b/test/unit/options/option_definition_test.rb
index e18233ae..f45dff3e 100644
--- a/test/unit/options/option_definition_test.rb
+++ b/test/unit/options/option_definition_test.rb
@@ -63,8 +63,8 @@ def opt_with_deprecation(deprecation)
       context = {}
       cmd = TestDeprecatedOptionCmd.new("", context)
 
-      out, err = capture_io { cmd.run(["--another-deprecated=VALUE"]) }
-      err.must_match /Warning: Option --another-deprecated is deprecated. It is going to be removed/
+      _, err = capture_io { cmd.run(["--another-deprecated=VALUE"]) }
+      err.must_match(/Warning: Option --another-deprecated is deprecated. It is going to be removed/)
       context[:old_option].must_equal "VALUE"
     end
 
@@ -72,8 +72,8 @@ def opt_with_deprecation(deprecation)
       context = {}
       cmd = TestDeprecatedOptionCmd.new("", context)
 
-      out, err = capture_io { cmd.run(["--deprecated=VALUE"]) }
-      err.must_match /Warning: Option --deprecated is deprecated. Use --test-option instead/
+      _, err = capture_io { cmd.run(["--deprecated=VALUE"]) }
+      err.must_match(/Warning: Option --deprecated is deprecated. Use --test-option instead/)
       context[:test_option].must_equal "VALUE"
     end
 
diff --git a/test/unit/options/sources/saved_defaults_test.rb b/test/unit/options/sources/saved_defaults_test.rb
index 1a63b531..9830f920 100644
--- a/test/unit/options/sources/saved_defaults_test.rb
+++ b/test/unit/options/sources/saved_defaults_test.rb
@@ -20,10 +20,6 @@
       @defaults.expects(:get_defaults).with('--test-multi1').returns(:first_value)
 
       current_result = {}
-      expected_result = {
-        :different_attr_name => 1,
-        :multiple_switches_option => :first_value
-      }
 
       @logger.expects(:info).with('Custom default value 1 was used for attribute --test')
       @logger.expects(:info).with('Custom default value first_value was used for attribute --test-multi1')
diff --git a/test/unit/output/adapter/abstract_test.rb b/test/unit/output/adapter/abstract_test.rb
index f4cd357b..ba3266a7 100644
--- a/test/unit/output/adapter/abstract_test.rb
+++ b/test/unit/output/adapter/abstract_test.rb
@@ -27,7 +27,7 @@ def required_features
   it "should filter formatters with incompatible features" do
 
     HammerCLI::Output::Formatters::FormatterLibrary.expects(:new).with({ :type => [] })
-    adapter = adapter_class.new({}, {:type => [UnknownTestFormatter.new]})
+    adapter_class.new({}, {:type => [UnknownTestFormatter.new]})
   end
 
   it "should keep compatible formatters" do
@@ -35,7 +35,7 @@ def required_features
     HammerCLI::Output::Formatters::FormatterLibrary.expects(:new).with({ :type => [formatter] })
     # set :unknown tag to abstract
     adapter_class.any_instance.stubs(:features).returns([:unknown])
-    adapter = adapter_class.new({}, {:type => [formatter]})
+    adapter_class.new({}, {:type => [formatter]})
   end
 
   it "should put serializers first" do
@@ -46,7 +46,7 @@ def required_features
     HammerCLI::Output::Formatters::FormatterLibrary.expects(:new).with({ :type => [formatter2, formatter1] })
     # set :unknown tag to abstract
     adapter_class.any_instance.stubs(:features).returns([:serialized])
-    adapter = adapter_class.new({}, {:type => [formatter1, formatter2]})
+    adapter_class.new({}, {:type => [formatter1, formatter2]})
   end
 
 
diff --git a/test/unit/output/adapter/csv_test.rb b/test/unit/output/adapter/csv_test.rb
index b1f56598..db07d999 100644
--- a/test/unit/output/adapter/csv_test.rb
+++ b/test/unit/output/adapter/csv_test.rb
@@ -24,28 +24,28 @@
 
     it "should print column name" do
       out, err = capture_io { adapter.print_collection(fields, data) }
-      out.must_match /.*Name,Started At.*/
-      err.must_match //
+      out.must_match(/.*Name,Started At.*/)
+      err.must_match(//)
     end
 
     it "should print field value" do
       out, err = capture_io { adapter.print_collection(fields, data) }
-      out.must_match /.*John Doe.*/
-      err.must_match //
+      out.must_match(/.*John Doe.*/)
+      err.must_match(//)
     end
 
     it "does not print fields which data are missing from api by default" do
       fields << field_login
       out, err = capture_io { adapter.print_collection(fields, data) }
-      out.wont_match /.*Login.*/
-      err.must_match //
+      out.wont_match(/.*Login.*/)
+      err.must_match(//)
     end
 
     it "prints fields which data are missing from api when field has hide_missing flag set to false" do
       fields << field_missing
       out, err = capture_io { adapter.print_collection(fields, data) }
-      out.must_match /.*Missing.*/
-      err.must_match //
+      out.must_match(/.*Missing.*/)
+      err.must_match(//)
     end
 
     context "handle ids" do
@@ -59,14 +59,14 @@
       }]}
 
       it "should ommit column of type Id by default" do
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.wont_match(/.*Id.*/)
         out.wont_match(/.*2000,.*/)
       end
 
       it "should print column of type Id when --show-ids is set" do
         adapter = HammerCLI::Output::Adapter::CSValues.new( { :show_ids => true } )
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.must_match(/.*Id.*/)
       end
     end
@@ -75,12 +75,12 @@
       let(:empty_data) { HammerCLI::Output::RecordCollection.new [] }
 
       it "should print headers by default" do
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.must_match(/.*Name.*/)
       end
 
       it "should print headers by default even if there is no data" do
-        out, err = capture_io { adapter.print_collection(fields, empty_data) }
+        out, _ = capture_io { adapter.print_collection(fields, empty_data) }
         out.must_match(/.*Name.*/)
       end
 
@@ -127,14 +127,14 @@
 
       it "should print column names" do
         out, err = capture_io { adapter.print_collection(fields, data) }
-        out.must_match /.*Demographics::Age,Demographics::Gender,Biometrics::Weight,Biometrics::Height*/
-        err.must_match //
+        out.must_match(/.*Demographics::Age,Demographics::Gender,Biometrics::Weight,Biometrics::Height*/)
+        err.must_match(//)
       end
 
       it "should print data" do
         out, err = capture_io { adapter.print_collection(fields, data) }
-        out.must_match /.*2000,22,m,123,155*/
-        err.must_match //
+        out.must_match(/.*2000,22,m,123,155*/)
+        err.must_match(//)
       end
     end
 
@@ -169,7 +169,7 @@
         lines = out.split("\n")
         lines[0].must_equal 'Name,Started At,Items::Item Name::1,Items::Item Quantity::1,Items::Item Name::2,Items::Item Quantity::2'
 
-        err.must_match //
+        err.must_match(//)
       end
 
       it "should print collection data" do
@@ -179,7 +179,7 @@
         lines[1].must_equal 'John Doe,2000,hammer,100,"",""'
         lines[2].must_equal 'Jane Roe,2001,cleaver,1,sledge,50'
 
-        err.must_match //
+        err.must_match(//)
       end
 
       it "should handle empty collection" do
@@ -188,7 +188,7 @@
 
         lines[0].must_equal 'Name,Started At,Items'
 
-        err.must_match //
+        err.must_match(//)
       end
 
     end
@@ -202,7 +202,7 @@ def format(data, field_params={})
         end
 
         adapter = HammerCLI::Output::Adapter::CSValues.new({}, { :Field => [ DotFormatter.new ]})
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.must_match(/.*-DOT-.*/)
       end
 
@@ -215,7 +215,7 @@ def format(data, field_params={})
 
         adapter = HammerCLI::Output::Adapter::CSValues.new({}, { :Field => [ NilFormatter.new ]})
         nil_data = HammerCLI::Output::RecordCollection.new [{ :name => nil }]
-        out, err = capture_io { adapter.print_collection([field_name], nil_data) }
+        out, _ = capture_io { adapter.print_collection([field_name], nil_data) }
         out.must_match(/.*NIL.*/)
       end
     end
diff --git a/test/unit/output/adapter/table_test.rb b/test/unit/output/adapter/table_test.rb
index 85313165..260d2263 100644
--- a/test/unit/output/adapter/table_test.rb
+++ b/test/unit/output/adapter/table_test.rb
@@ -94,7 +94,7 @@
       }
 
       it "should ommit column of type Id by default" do
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.wont_match(/.*ID.*/)
       end
 
@@ -110,7 +110,7 @@
 
       it "should print column of type Id when --show-ids is set" do
         adapter = HammerCLI::Output::Adapter::Table.new( { :show_ids => true } )
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.must_match(/.*ID.*/)
       end
 
@@ -128,12 +128,12 @@
 
     context "handle headers" do
       it "should print headers by default" do
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.must_match(/.*NAME.*/)
       end
 
       it "should print headers by default even if there is no data" do
-        out, err = capture_io { adapter.print_collection(fields, empty_data) }
+        out, _ = capture_io { adapter.print_collection(fields, empty_data) }
         out.must_match(/.*NAME.*/)
       end
 
@@ -353,7 +353,7 @@ def format(data, field_params={})
         end
 
         adapter = HammerCLI::Output::Adapter::Table.new({}, { :Field => [ DotFormatter.new ]})
-        out, err = capture_io { adapter.print_collection(fields, data) }
+        out, _ = capture_io { adapter.print_collection(fields, data) }
         out.must_match(/.*-DOT-.*/)
       end