Load Rake tasks only once for command suggestions

railties/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   `bin/rails --help` will now list only framework and plugin commands. Rake
+    tasks defined in `lib/tasks/*.rake` files will no longer be included. For a
+    list of those tasks, use `rake -T`.
+
+    *Jonathan Hefner*
+
 *   Allow calling `bin/rails restart` outside of app directory.
 
     The following would previously fail with a "No Rakefile found" error.

railties/lib/rails/commands/rake/rake_command.rb

@@ -9,46 +9,45 @@ class RakeCommand < Base # :nodoc:
 
       class << self
         def printing_commands
-          formatted_rake_tasks
+          rake_tasks.filter_map do |task|
+            if task.comment && task.locations.any?(non_app_file_pattern)
+              [task.name_with_args, task.comment]
+            end
+          end
         end
 
         def perform(task, args, config)
-          require_rake
-
-          Rake.with_application do |rake|
-            rake.init("bin/rails", [task, *args])
-            rake.load_rakefile
+          with_rake(task, *args) do |rake|
             if unrecognized_task = rake.top_level_tasks.find { |task| !rake.lookup(task[/[^\[]+/]) }
+              @rake_tasks = rake.tasks
               raise UnrecognizedCommandError.new(unrecognized_task)
             end
 
-            if Rails.respond_to?(:root)
-              rake.options.suppress_backtrace_pattern = /\A(?!#{Regexp.quote(Rails.root.to_s)})/
-            end
+            rake.options.suppress_backtrace_pattern = non_app_file_pattern
             rake.standard_exception_handling { rake.top_level }
           end
         end
 
         private
-          def rake_tasks
-            require_rake
-
-            return @rake_tasks if defined?(@rake_tasks)
-
-            require_application!
+          def non_app_file_pattern
+            /\A(?!#{Regexp.quote Rails::Command.root.to_s})/
+          end
 
+          def with_rake(*args, &block)
+            require "rake"
             Rake::TaskManager.record_task_metadata = true
-            Rake.application.instance_variable_set(:@name, "rails")
-            load_tasks
-            @rake_tasks = Rake.application.tasks.select(&:comment)
-          end
 
-          def formatted_rake_tasks
-            rake_tasks.map { |t| [ t.name_with_args, t.comment ] }
+            result = nil
+            Rake.with_application do |rake|
+              rake.init(bin, args) unless args.empty?
+              rake.load_rakefile
+              result = block.call(rake)
+            end
+            result
           end
 
-          def require_rake
-            require "rake" # Defer booting Rake until we know it's needed.
+          def rake_tasks
+            @rake_tasks ||= with_rake(&:tasks)
           end
       end
     end

railties/test/command/help_integration_test.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require "isolation/abstract_unit"
+require "rails/command"
+
+class Rails::Command::HelpIntegrationTest < ActiveSupport::TestCase
+  setup :build_app
+  teardown :teardown_app
+
+  test "prints helpful error on unrecognized command" do
+    output = rails "vershen", allow_failure: true
+
+    assert_match %(Unrecognized command "vershen"), output
+    assert_match "Did you mean?  version", output
+  end
+
+  test "loads Rake tasks only once on unrecognized command" do
+    app_file "lib/tasks/my_task.rake", <<~RUBY
+      puts "MY_TASK already defined? => \#{!!defined?(MY_TASK)}"
+      MY_TASK = true
+    RUBY
+
+    output = rails "vershen", allow_failure: true
+
+    assert_match "MY_TASK already defined? => false", output
+    assert_no_match "MY_TASK already defined? => true", output
+  end
+
+  test "prints help via `X:help` command when running `X` and `X:X` command is not defined" do
+    help = rails "dev:help"
+    output = rails "dev", allow_failure: true
+
+    assert_equal help, output
+  end
+
+  test "excludes application Rake tasks from command listing" do
+    app_file "Rakefile", <<~RUBY, "a"
+      desc "my_task"
+      task :my_task_1
+    RUBY
+
+    app_file "lib/tasks/my_task.rake", <<~RUBY
+      desc "my_task"
+      task :my_task_2
+    RUBY
+
+    assert_no_match "my_task", rails("--help")
+  end
+end

railties/test/commands/application_test.rb

@@ -0,0 +1,22 @@
+# 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 = run_application_command "new"
+
+    # 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
+
+  private
+    def run_application_command(*args)
+      capture(:stdout) { Rails::Command.invoke(:application, args) }
+    end
+end