[ruby/irb] Improve help message for no meta commands

(https://github.com/ruby/irb/pull/948)

* Remove unnecessary code from command tests

* Improve help message for no meta commands

1. Add placeholder values for both command category and description
2. Update help command's output to give different types of categories
   more explicit ordering

https://github.com/ruby/irb/commit/b1ef58aeff

lib/irb/command/base.rb

@@ -18,12 +18,12 @@ module IRB
       class << self
         def category(category = nil)
           @category = category if category
-          @category
+          @category || "No category"
         end
 
         def description(description = nil)
           @description = description if description
-          @description
+          @description || "No description provided."
         end
 
         def help_message(help_message = nil)

lib/irb/command/help.rb

@@ -12,7 +12,7 @@ module IRB
             help_message
           else
             if command_class = Command.load_command(command_name)
-              command_class.help_message || command_class.description || ""
+              command_class.help_message || command_class.description
             else
               "Can't find command `#{command_name}`. Please check the command name and try again.\n\n"
             end
@@ -28,17 +28,9 @@ module IRB
         commands_grouped_by_categories = commands_info.group_by { |cmd| cmd[:category] }
         commands_grouped_by_categories["Helper methods"] = helper_methods_info
 
-        user_aliases = irb_context.instance_variable_get(:@user_aliases)
-
-        commands_grouped_by_categories["Aliases"] = user_aliases.map do |alias_name, target|
-          { display_name: alias_name, description: "Alias for `#{target}`" }
-        end
-
         if irb_context.with_debugger
           # Remove the original "Debugging" category
           commands_grouped_by_categories.delete("Debugging")
-          # Add an empty "Debugging (from debug.gem)" category at the end
-          commands_grouped_by_categories["Debugging (from debug.gem)"] = []
         end
 
         longest_cmd_name_length = commands_info.map { |c| c[:display_name].length }.max
@@ -46,15 +38,31 @@ module IRB
         output = StringIO.new
 
         help_cmds = commands_grouped_by_categories.delete("Help")
+        no_category_cmds = commands_grouped_by_categories.delete("No category")
+        aliases = irb_context.instance_variable_get(:@user_aliases).map do |alias_name, target|
+          { display_name: alias_name, description: "Alias for `#{target}`" }
+        end
 
+        # Display help commands first
         add_category_to_output("Help", help_cmds, output, longest_cmd_name_length)
 
+        # Display the rest of the commands grouped by categories
         commands_grouped_by_categories.each do |category, cmds|
           add_category_to_output(category, cmds, output, longest_cmd_name_length)
         end
 
+        # Display commands without a category
+        if no_category_cmds
+          add_category_to_output("No category", no_category_cmds, output, longest_cmd_name_length)
+        end
+
+        # Display aliases
+        add_category_to_output("Aliases", aliases, output, longest_cmd_name_length)
+
         # Append the debugger help at the end
         if irb_context.with_debugger
+          # Add "Debugging (from debug.gem)" category as title
+          add_category_to_output("Debugging (from debug.gem)", [], output, longest_cmd_name_length)
           output.puts DEBUGGER__.help
         end
 

test/irb/command/test_custom_command.rb

@@ -15,7 +15,6 @@ module TestIRB
           description 'print_command'
           def execute(*)
             puts "Hello from PrintCommand"
-            nil
           end
         end
 
@@ -25,7 +24,7 @@ module TestIRB
       RUBY
 
       output = run_ruby_file do
-        type "print!\n"
+        type "print!"
         type "exit"
       end
 
@@ -41,7 +40,6 @@ module TestIRB
           description 'print_command'
           def execute(*)
             puts "Hello from PrintCommand"
-            nil
           end
         end
 
@@ -51,7 +49,7 @@ module TestIRB
       RUBY
 
       output = run_ruby_file do
-        type "print!\n"
+        type "print!"
         type "exit"
       end
 
@@ -69,7 +67,6 @@ module TestIRB
             $nth_execution ||= 0
             puts "\#{$nth_execution} arg=\#{arg.inspect}"
             $nth_execution += 1
-            nil
           end
         end
 
@@ -79,9 +76,9 @@ module TestIRB
       RUBY
 
       output = run_ruby_file do
-        type "print_arg\n"
+        type "print_arg"
         type "print_arg  \n"
-        type "print_arg a r  g\n"
+        type "print_arg a r  g"
         type "print_arg  a r  g  \n"
         type "exit"
       end
@@ -103,7 +100,6 @@ module TestIRB
             $nth_execution ||= 1
             puts "\#{$nth_execution} FooBar executed"
             $nth_execution += 1
-            nil
           end
         end
 
@@ -131,7 +127,6 @@ module TestIRB
         class NoMetaCommand < IRB::Command::Base
           def execute(*)
             puts "This command does not override meta attributes"
-            nil
           end
         end
 
@@ -141,12 +136,13 @@ module TestIRB
       RUBY
 
       output = run_ruby_file do
-        type "no_meta\n"
-        type "help no_meta\n"
+        type "no_meta"
+        type "help no_meta"
         type "exit"
       end
 
       assert_include(output, "This command does not override meta attributes")
+      assert_include(output, "No description provided.")
       assert_not_include(output, "Maybe IRB bug")
     end
   end