[ruby/reline] Add a test for full-width scrollbar

https://github.com/ruby/reline/commit/cff83e68f8

test/reline/yamatanooroti/multiline_repl

@@ -74,8 +74,14 @@ opt.on('--dialog VAL') { |v|
     if v.include?('scrollbar')
       scrollbar = true
     end
+    if v.include?('alt-scrollbar')
+      scrollbar = true
+    end
     Reline::DialogRenderInfo.new(pos: cursor_pos, contents: contents, height: height, scrollbar: scrollbar)
   })
+  if v.include?('alt-scrollbar')
+    ENV['RELINE_ALT_SCROLLBAR'] = '1'
+  end
 }
 opt.on('--complete') {
   Reline.completion_proc = lambda { |target, preposing = nil, postposing = nil|

test/reline/yamatanooroti/test_rendering.rb

@@ -1114,6 +1114,19 @@ begin
       EOC
     end
 
+    def test_dialog_with_fullwidth_scrollbar
+      start_terminal(20, 40, %W{ruby -I#{@pwd}/lib #{@pwd}/test/reline/yamatanooroti/multiline_repl --dialog simple,scrollkey,alt-scrollbar}, startup_message: 'Multiline REPL.')
+      close
+      assert_screen(<<~'EOC')
+        Multiline REPL.
+        prompt>
+           Ruby is...                         ::
+           A dynamic, open source programming ::
+           language with a focus on simplicity''
+           and productivity. It has an elegant
+      EOC
+    end
+
     def test_rerender_argument_prompt_after_pasting
       start_terminal(20, 30, %W{ruby -I#{@pwd}/lib #{@pwd}/test/reline/yamatanooroti/multiline_repl}, startup_message: 'Multiline REPL.')
       write('abcdef')