exe/benchmark-driver in benchmark_driver-0.4.5 vs exe/benchmark-driver in benchmark_driver-0.5.0

@@ -1,24 +1,27 @@
 #!/usr/bin/env ruby
 $:.unshift File.expand_path('../lib', __dir__)
 
 require 'benchmark/driver'
+require 'benchmark/driver/bundle_installer'
 require 'benchmark/driver/yaml_parser'
 require 'optparse'
 require 'yaml'
 
 options = {}
-args = OptionParser.new do |o|
+parser = OptionParser.new do |o|
   o.banner = "Usage: #{File.basename($0, '.*')} [options] [YAML]"
   o.on('-e', '--executables [EXECS]', 'Ruby executables (e1::path1,arg1,...; e2::path2,arg2;...)') do |e|
+    abort '-e, --executable must take argument but not given' if e.nil?
     options[:execs] ||= []
     e.split(';').each do |name_path|
       name, path = name_path.split('::', 2)
       options[:execs] << Benchmark::Driver::Configuration::Executable.new(name, path ? path.split(',') : [name])
     end
   end
   o.on('--rbenv [VERSIONS]', 'Ruby executables in rbenv (x.x.x,arg1,...;y.y.y,arg2,...;...)') do |r|
+    abort '--rbenv must take argument but not given' if r.nil?
     options[:execs] ||= []
     r.split(';').each do |spec|
       version, *args = spec.split(',')
       path = `RBENV_VERSION='#{version}' rbenv which ruby`.rstrip
       abort "Failed to execute 'rbenv which ruby'" unless $?.success?
@@ -37,18 +40,21 @@
   end
   o.on('--filter [REGEXP]', 'Filter out benchmarks with given regexp') do |v|
     abort '--filter can be used only once' if options.key?(:filter)
     options[:filter] = v
   end
-  o.on('--bundler', 'Use gems specified in Gemfile (append -rbundler/setup)') do |v|
+  o.on('--bundler', 'Install and use gems specified in Gemfile') do |v|
     options[:bundler] = v
   end
   o.on('--dir', 'Override __dir__ from "/tmp" to actual directory of YAML') do |v|
     options[:dir] = v
   end
-end.parse!(ARGV)
-abort "No YAML file is specified" if args.empty?
+end
+args = parser.parse!(ARGV)
+if args.empty?
+  abort "No YAML file is specified!\n\n#{parser.help}"
+end
 
 args.each do |path|
   yaml = YAML.load(File.read(path))
   Benchmark::Driver::Configuration.symbolize_keys!(yaml)
 
@@ -68,9 +74,10 @@
 
   options.each do |key, value|
     case key
     when :bundler
       config.runner_options.executables.each do |executable|
+        Benchmark::Driver::BundleInstaller.bundle_install_for(executable)
         executable.command << '-rbundler/setup'
       end
     when :compare
       config.output_options.compare = value
     when :dir