Railsチュートリアル　第三章　rails test でminitest を認識しない

前提・実現したいこと

rails test のエラー解決をしたい。

Ruby on Rails チュートリアル第4版第3章3.6.1 minitest reporters

発生している問題・エラーメッセージ

ec2-user:~/environment/sample_app (master) $ rails test
Running via Spring preloader in process 9810
Traceback (most recent call last):
        46: from -e:1:in `<main>'
        45: from /home/ec2-user/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        44: from /home/ec2-user/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        43: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:286:in `load'
        42: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
        41: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:286:in `block in load'
        40: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:286:in `load'
        39: from /home/ec2-user/environment/sample_app/bin/rails:9:in `<top (required)>'
        38: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        37: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
        36: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
        35: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        34: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/commands.rb:16:in `<top (required)>'
        33: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/command.rb:44:in `invoke'
        32: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/command/base.rb:63:in `perform'
        31: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/thor-1.0.1/lib/thor.rb:392:in `dispatch'
        30: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/thor-1.0.1/lib/thor/invocation.rb:127:in `invoke_command'
        29: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/thor-1.0.1/lib/thor/command.rb:27:in `run'
        28: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/commands/test/test_command.rb:38:in `perform'
        27: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/test_unit/runner.rb:39:in `run'
        26: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/test_unit/runner.rb:50:in `load_tests'
        25: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/test_unit/runner.rb:50:in `each'
        24: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/test_unit/runner.rb:50:in `block in load_tests'
        23: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        22: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
        21: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
        20: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        19: from /home/ec2-user/environment/sample_app/test/controllers/static_pages_controller_test.rb:1:in `<top (required)>'
        18: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        17: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
        16: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
        15: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        14: from /home/ec2-user/environment/sample_app/test/test_helper.rb:3:in `<top (required)>'
        13: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
        12: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
        11: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
        10: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
         9: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/railties-5.1.6/lib/rails/test_help.rb:5:in `<top (required)>'
         8: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
         7: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
         6: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
         5: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
         4: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/test_case.rb:2:in `<top (required)>'
         3: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
         2: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
         1: from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
/home/ec2-user/.rvm/gems/ruby-2.6.3/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require': cannot load such file -- minitest (LoadError)
ec2-user:~/environment/sample_app (master) $

ここに言語名を入力
Ruby on Rails
cloud9

Gemfileは下記の通り

source 'https://rubygems.org'

gem 'rails',        '5.1.6'
gem 'puma',         '3.9.1'
gem 'sass-rails',   '5.0.6'
gem 'uglifier',     '3.2.0'
gem 'coffee-rails', '4.2.2'
gem 'jquery-rails', '4.3.1'
gem 'turbolinks',   '5.0.1'
gem 'jbuilder',     '2.7.0'

group :development, :test do
  gem 'sqlite3',      '~> 1.3.6'
  gem 'byebug', '9.0.6', platform: :mri
end

group :development do
  gem 'web-console',           '3.5.1'
  gem 'listen',                '3.1.5'
  gem 'spring',                '2.0.2'
  gem 'spring-watcher-listen', '2.0.1'
end

group :test do
  gem 'rails-controller-testing', '1.0.2'
  gem 'minitest',                 '5.10.3'
  gem 'minitest-reporters',       '1.1.14'
  gem 'guard',                    '2.16.2'
  gem 'guard-minitest',           '2.4.4'
end

group :production do
  gem 'pg', '0.20.0'
end

# Windows環境ではtzinfo-dataというgemを含める必要があります
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]