Merge pull request #42220 from ghiculescu/rails-new-no-path-provided

Display a help message if `rails new` is called without a path

railties/lib/rails/command.rb

@@ -38,6 +38,7 @@ module Rails
         end
 
         command_name, namespace = "help", "help" if command_name.blank? || HELP_MAPPINGS.include?(command_name)
+        command_name, namespace, args = "application", "application", ["--help"] if rails_new_with_no_path?(args)
         command_name, namespace = "version", "version" if %w( -v --version ).include?(command_name)
 
         original_argv = ARGV.dup
@@ -92,6 +93,10 @@ module Rails
         COMMANDS_IN_USAGE = %w(generate console server test test:system dbconsole new)
         private_constant :COMMANDS_IN_USAGE
 
+        def rails_new_with_no_path?(args)
+          args == ["new"]
+        end
+
         def commands
           lookup!
 

railties/test/command/application_test.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "rails/command"
+
+class Rails::Command::ApplicationTest < ActiveSupport::TestCase
+  test "rails new without path prints help" do
+    output = capture(:stdout) do
+      Rails::Command.invoke(:application, %w[new])
+    end
+
+    # Doesn't include the default thor error message:
+    assert_not output.start_with?("No value provided for required arguments")
+
+    # Includes contents of ~/railties/lib/rails/generators/rails/app/USAGE:
+    assert output.include?("The 'rails new' command creates a new Rails application with a default
+    directory structure and configuration at the path you specify.")
+  end
+end