Port test_warn_dash_gem.rb to RSpec example

spec/bundler/bundled_gems_spec.rb

@@ -22,4 +22,20 @@ RSpec.describe "bundled_gems.rb" do
     expect(err).to include(/csv was loaded from (.*) from Ruby 3.4.0/)
     expect(err).to include(/ostruct was loaded from (.*) from Ruby 3.5.0/)
   end
+
+  it "Show warning dash gem like net/smtp" do
+    script <<-RUBY
+      gemfile do
+        source "https://rubygems.org"
+      end
+
+      begin
+        require "net/smtp"
+      rescue LoadError
+      end
+    RUBY
+
+    expect(err).to include(/net\/smtp was loaded from (.*) from Ruby 3.1.0/)
+    expect(err).to include("You can add net-smtp")
+  end
 end

tool/test_for_warn_bundled_gems/test.sh

@@ -8,10 +8,6 @@ echo "* Show warning sub-feature like bigdecimal/util"
 ruby test_warn_sub_feature.rb
 echo
 
-echo "* Show warning dash gem like net/smtp"
-ruby test_warn_dash_gem.rb
-echo
-
 echo "* Show warning when bundle exec with ruby and script"
 bundle exec ruby test_warn_bundle_exec.rb
 echo

tool/test_for_warn_bundled_gems/test_warn_dash_gem.rb

@@ -1,10 +0,0 @@
-require "bundler"
-Bundler::Definition.no_lock = true
-
-require "bundler/inline"
-
-gemfile do
-  source "https://rubygems.org"
-end
-
-require "net/smtp"