Add tree flag

This allows you to run `app --tree` to see a tree of all available commands.

Author: hlascelles

lib/thor.rb

@@ -671,4 +671,37 @@ def help(command = nil, subcommand = false)
       self.class.help(shell, subcommand)
     end
   end
+
+  map TREE_MAPPINGS => :tree
+
+  desc "tree", "Print a tree of all available commands"
+  def tree
+    build_command_tree(self.class, "")
+  end
+
+private
+
+  def build_command_tree(klass, indent)
+    # Print current class name if it's not the root Thor class
+    unless klass == Thor
+      say "#{indent}#{klass.namespace || 'default'}", :blue
+      indent = "#{indent}  "
+    end
+
+    # Print all commands for this class
+    visible_commands = klass.commands.reject { |_, cmd| cmd.hidden? || cmd.name == "help" }
+    commands_count = visible_commands.count
+    visible_commands.sort.each_with_index do |(command_name, command), i|
+      description = command.description.split("\n").first || ""
+      icon = i == (commands_count - 1) ? "└─" : "├─"
+      say "#{indent}#{icon} ", nil, false
+      say command_name, :green, false
+      say " (#{description})" unless description.empty?
+    end
+
+    # Print all subcommands (from registered Thor subclasses)
+    klass.subcommand_classes.each do |_, subclass|
+      build_command_tree(subclass, indent)
+    end
+  end
 end

lib/thor/base.rb

@@ -13,8 +13,9 @@ class Thor
   autoload :RakeCompat, File.expand_path("rake_compat", __dir__)
   autoload :Group,      File.expand_path("group", __dir__)
 
-  # Shortcuts for help.
+  # Shortcuts for help and tree commands.
   HELP_MAPPINGS       = %w(-h -? --help -D)
+  TREE_MAPPINGS       = %w(-t --tree)
 
   # Thor methods that should not be overwritten by the user.
   THOR_RESERVED_WORDS = %w(invoke shell options behavior root destination_root relative_root

spec/tree_spec.rb

@@ -0,0 +1,49 @@
+require "helper"
+require "thor"
+
+class TreeApp < Thor
+  desc "command1", "A top level command"
+
+  def command1
+  end
+
+  desc "command2", "Another top level command"
+
+  def command2
+  end
+
+  class SubApp < Thor
+    desc "subcommand1", "A subcommand"
+
+    def subcommand1
+    end
+  end
+
+  desc "sub", "Subcommands"
+  subcommand "sub", SubApp
+end
+
+RSpec.describe "Thor tree command" do
+  let(:shell) { Thor::Shell::Basic.new }
+
+  it "prints a tree of all commands" do
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/├─ command1/)
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/├─ command2/)
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/└─ sub/)
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/subcommand1/)
+  end
+
+  it "includes command descriptions" do
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/A top level command/)
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/Another top level command/)
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).to match(/A subcommand/)
+  end
+
+  it "doesn't show hidden commands" do
+    expect(capture(:stdout) { TreeApp.start(["tree"]) }).not_to match(/help/)
+  end
+
+  it "shows tree command in help" do
+    expect(capture(:stdout) { TreeApp.start(["help"]) }).to match(/tree.*Print a tree of all available commands/)
+  end
+end