mbeditor

Mbeditor (Mini Browser Editor) is a mountable Rails engine that adds a browser-based editor UI to a Rails app.

• Two-pane tabbed editor with drag-to-move tabs
• File tree and project search
• Git panel with working tree changes, unpushed file changes, and branch commit titles
• Optional RuboCop lint and format endpoints (uses host app RuboCop)
• Optional test runner with inline failure markers and a dedicated results panel (Minitest and RSpec)

Mbeditor exposes read and write access to your Rails application directory over HTTP. It is intended only for local development.

• Never install mbeditor in production or staging.
• Never run it on infrastructure accessible to untrusted users.
• Always keep it in the development group in your Gemfile.
• The engine enforces environment restrictions at runtime, and Gemfile scoping is a second line of defense that keeps the gem out of deploy builds.

1. Add the gem to the host app Gemfile in development only:

gem 'mbeditor', group: :development

2. Install dependencies:

bundle install

3. Mount the engine in host app routes:

mount Mbeditor::Engine, at: "/mbeditor"

4. Create config/initializers/mbeditor.rb using the configuration options below.

5. Boot your app and open /mbeditor.

Use a single initializer to set the engine options you need:

Mbeditor.configure do |config|
  config.allowed_environments = [:development]
  # config.workspace_root = Rails.root
  config.excluded_paths = %w[.git tmp log node_modules .bundle coverage vendor/bundle]
  config.rubocop_command = "bundle exec rubocop"

  # Optional authentication (runs as a before_action in the engine controllers)
  # config.authenticate_with = proc { redirect_to login_path unless UserSession.find }

  # Optional test runner (Minitest or RSpec)
  # config.test_framework = :minitest   # :minitest or :rspec — auto-detected when nil
  # config.test_command   = "bundle exec rails test"  # defaults to bin/rails test or bundle exec ruby -Itest
  # config.test_timeout   = 60

  # Optional Redmine integration
  # config.redmine_enabled = true
  # config.redmine_url = "https://redmine.example.com/"
  # config.redmine_api_key = "optional_api_key_override"
  # config.redmine_ticket_source = :commit  # :commit (scan recent commit messages for #123) or :branch (leading digits of branch name)
end

Available options:

• allowed_environments controls which Rails environments can access the engine. Default: [:development].
• authenticate_with accepts a proc that runs as a before_action in all engine controllers. Use it to plug in the host app's authentication. The proc executes via instance_exec inside the engine controller, so it has access to session, cookies, redirect_to, and auth library class methods (e.g. Authlogic's UserSession.find), but not helper methods defined in the host app's ApplicationController. Default: nil (no authentication).
• workspace_root sets the root directory exposed by Mbeditor. Default: Rails.root from the host app.
• excluded_paths hides files and directories from the tree and path-based operations. Entries without / match names anywhere in the workspace path; entries with / match relative paths and their descendants. Default: %w[.git tmp log node_modules .bundle coverage vendor/bundle].
• rubocop_command sets the command used for inline Ruby linting and formatting. Default: "rubocop".
• test_framework sets the test framework. :minitest or :rspec. Auto-detected from file suffix, .rspec, or test/spec directory when nil. Default: nil.
• test_command overrides the full command used to run a test file. When nil, the engine picks bin/rails test (Minitest) or bin/rspec / bundle exec rspec (RSpec). Default: nil.
• test_timeout sets the maximum seconds a test run may take before being killed. Default: 60.
• redmine_enabled enables issue lookup integration. Default: false.
• redmine_url sets the Redmine base URL. Required when redmine_enabled is true.
• redmine_api_key sets the Redmine API key. Required when redmine_enabled is true.
• redmine_ticket_source controls how the current Redmine ticket is identified. :commit scans the 100 most recent branch commits for a #123 reference in the commit message. :branch reads the leading digits from the branch name (e.g. 123-my-feature → ticket 123). Default: :commit.

The Test button appears in the editor toolbar for any .rb file when a test/ or spec/ directory exists in the workspace root. Clicking it:

1. Resolves the active source file to its matching test file using standard Rails conventions (app/models/user.rb → test/models/user_test.rb). If the open file is already a test file, it runs that file directly.
2. Runs the test file using the configured command in a subprocess with a timeout.
3. Shows a Test Results panel with pass/fail counts, per-test status icons, and error messages.
4. Optionally overlays inline failure markers in the Monaco editor (separate from RuboCop markers — the two never interfere). Use the marker icon in the panel header to toggle them.

Framework auto-detection order:

1. File suffix: _spec.rb → RSpec, _test.rb → Minitest
2. .rspec file present → RSpec
3. spec/ directory present → RSpec
4. test/ directory present → Minitest

Default commands (when test_command is not set):

• Minitest: bin/rails test <file> if bin/rails exists, otherwise bundle exec ruby -Itest <file>
• RSpec: bin/rspec <file> if bin/rspec exists, otherwise bundle exec rspec --format json <file>

The gem keeps host/tooling responsibilities in the host app:

• rubocop and rubocop-rails gems (optional, required for Ruby lint/format endpoints)
• haml_lint gem (optional, required for HAML lint — add to your app's Gemfile if needed)
• git installed in environment (for Git panel data)
• minitest or rspec in the host app's bundle (required for the test runner)

All lint and test tools are auto-detected at runtime. The engine gracefully disables features if the tools are not available. Neither rubocop, haml_lint, nor any test framework are runtime dependencies of the gem itself — they are discovered from the host app's environment.

Monaco runtime assets are served from the engine route namespace (/mbeditor/monaco-editor/* and /mbeditor/monaco_worker.js). The gem includes syntax highlighting for common Rails and React development file types:

Web & Template Languages:

• Ruby (.rb, Gemfile, gemspec, Rakefile)
• HTML
• ERB (.html.erb, .erb) — Handlebars-based template syntax
• HAML (.haml) — plaintext syntax highlighting (no dedicated HAML grammar in Monaco; haml-lint provides inline error markers when available)
• CSS and SCSS stylesheets

JavaScript & React:

• JavaScript (.js, .jsx)
• TypeScript for JSX with full language server support

Configuration & Documentation:

• YAML (.yml, .yaml)
• Markdown (.md)

These language modules are packaged locally with the gem for true offline operation. No network fallback is needed—all highlighting works without internet connectivity.

Mbeditor requires Sprockets (sprockets-rails >= 3.4). Host apps using Propshaft as their asset pipeline are not supported — the engine depends on Sprockets directives to load its JavaScript and CSS assets.

A minimal dummy Rails app is included for local development and testing:

cd test/dummy && rails server

Then visit http://localhost:3000/mbeditor.

The test suite uses Minitest via the dummy Rails app. Run all tests from the project root:

bundle exec rake test

Run a single test file:

bundle exec ruby -Itest test/controllers/mbeditor/editors_controller_test.rb

Run a single test by name:

bundle exec ruby -Itest test/controllers/mbeditor/editors_controller_test.rb -n test_ping_returns_ok