Introduce 'suspenders:lint` generator

Closes #1107
Closes #1143

Creates a holistic linting solution that covers JavaScript, CSS, Ruby
and ERB.

Introduces [scripts][] that leverage [@thoughtbot/eslint-config][],
[@thoughtbot/stylelint-config][] and [prettier][].

Also introduces `.prettierrc` based off of our [Guides][].

[scripts]: https://docs.npmjs.com/cli/v6/using-npm/scripts
[@thoughtbot/eslint-config]: https://github.com/thoughtbot/eslint-config
[@thoughtbot/stylelint-config]: https://github.com/thoughtbot/stylelint-config
[prettier]: https://prettier.io
[Guides]: https://github.com/thoughtbot/guides/blob/main/javascript/README.md#formatting

Introduces `rake standard` which also runs `erblint` to lint ERB files
via [better_html][], [erb_lint][] and [erblint-github][].

[better_html]: https://github.com/Shopify/better-html
[erb_lint]: https://github.com/Shopify/erb-lint
[erblint-github]: https://github.com/github/erblint-github

A future commit will ensure these linting rules are run during CI. In an
effort to support that future commit, we ensure to run `yarn run
fix:prettier` and `bundle exec standard:fix_unsafely` once the generator
is complete. Otherwise, CI would fail because of linting violations.

We call `standard:fix_unsafely` since `standard:fix` returns an error
status code on new Rails applications. Running `standard:fix_unsafely`
fixes this issue and returns a success status code.

It should be noted that we deliberately permit this generator to be
invoked on API only applications, because those applications can still
contain views, like ones used for mailers.

Also improves the developer experience by introducing `with_test_suite`
helper, allowing the caller to run the generator in an application using
minitest or RSpec.

NEWS.md

@@ -7,6 +7,7 @@ Unreleased
 * Introduce `suspenders:advisories` generator
 * Introduce `suspenders:styles` generator
 * Introduce `suspenders:jobs` generator
+* Introduce `suspenders:lint` generator
 
 20230113.0 (January, 13, 2023)
 

README.md

@@ -72,6 +72,26 @@ improvement for the viewer.
 
   [inline_svg]: https://github.com/jamesmartin/inline_svg
 
+### Lint
+
+Creates a holistic linting solution that covers JavaScript, CSS, Ruby and ERB.
+
+Introduces NPM commands that leverage [@thoughtbot/eslint-config][],
+[@thoughtbot/stylelint-config][] and [prettier][].
+
+Also introduces `.prettierrc` based off of our [Guides][].
+
+Introduces `rake standard` which also runs `erblint` to lint ERB files
+via [better_html][], [erb_lint][] and [erblint-github][].
+
+[@thoughtbot/eslint-config]: https://github.com/thoughtbot/eslint-config
+[@thoughtbot/stylelint-config]: https://github.com/thoughtbot/stylelint-config
+[prettier]: https://prettier.io
+[Guides]: https://github.com/thoughtbot/guides/blob/main/javascript/README.md#formatting
+[better_html]: https://github.com/Shopify/better-html
+[erb_lint]: https://github.com/Shopify/erb-lint
+[erblint-github]: https://github.com/github/erblint-github
+
 ### Styles
 
 Configures applications to use [PostCSS][] or [Tailwind][] via

lib/generators/suspenders/lint_generator.rb

@@ -0,0 +1,77 @@
+module Suspenders
+  module Generators
+    class LintGenerator < Rails::Generators::Base
+      include Suspenders::Generators::Helpers
+
+      source_root File.expand_path("../../templates/lint", __FILE__)
+      desc "Creates a holistic linting solution that covers JavaScript, CSS, Ruby and ERB."
+
+      def install_dependencies
+        run "yarn add stylelint@^15.10.1 eslint @thoughtbot/[email protected] @thoughtbot/eslint-config npm-run-all prettier --dev"
+      end
+
+      def install_gems
+        gem_group :development, :test do
+          gem "better_html", require: false
+          gem "erb_lint", require: false
+          gem "erblint-github", require: false
+          gem "standard"
+        end
+        Bundler.with_unbundled_env { run "bundle install" }
+      end
+
+      def configure_stylelint
+        copy_file "stylelintrc.json", ".stylelintrc.json"
+      end
+
+      def configure_eslint
+        copy_file "eslintrc.json", ".eslintrc.json"
+      end
+
+      def configure_prettier
+        copy_file "prettierrc", ".prettierrc"
+      end
+
+      def configure_erb_lint
+        copy_file "erb-lint.yml", ".erb-lint.yml"
+        copy_file "config_better_html.yml", "config/better_html.yml"
+        copy_file "config_initializers_better_html.rb", "config/initializers/better_html.rb"
+        copy_file "erblint.rake", "lib/tasks/erblint.rake"
+        template "rubocop.yml.tt", ".rubocop.yml"
+
+        if default_test_suite?
+          copy_file "better_html_test.rb", "test/views/better_html_test.rb"
+        elsif rspec_test_suite?
+          copy_file "better_html_spec.rb", "spec/views/better_html_spec.rb"
+        end
+      end
+
+      def update_package_json
+        content = File.read package_json
+        json = JSON.parse content
+        json["scripts"] ||= {}
+
+        json["scripts"]["lint"] = "run-p lint:eslint lint:stylelint lint:prettier"
+        json["scripts"]["lint:eslint"] = "eslint --max-warnings=0 --no-error-on-unmatched-pattern 'app/javascript/**/*.js'"
+        json["scripts"]["lint:stylelint"] = "stylelint 'app/assets/stylesheets/**/*.css'"
+        json["scripts"]["lint:prettier"] = "prettier --check '**/*' --ignore-unknown"
+        json["scripts"]["fix:prettier"] = "prettier --write '**/*' --ignore-unknown"
+
+        File.write package_json, JSON.pretty_generate(json)
+      end
+
+      # This needs to be the last method definition to ensure everything is
+      # properly configured
+      def fix_violations
+        run "yarn run fix:prettier"
+        run "bundle exec rake standard:fix_unsafely"
+      end
+
+      private
+
+      def package_json
+        Rails.root.join("package.json")
+      end
+    end
+  end
+end

lib/generators/templates/lint/better_html_spec.rb

@@ -0,0 +1,17 @@
+require "spec_helper"
+
+describe "ERB Implementation" do
+  def self.erb_lint
+    configuration = ActiveSupport::ConfigurationFile.parse(".erb-lint.yml")
+
+    ActiveSupport::OrderedOptions.new.merge!(configuration.deep_symbolize_keys!)
+  end
+
+  Rails.root.glob(erb_lint.glob).each do |template|
+    it "raises no html errors in #{template.relative_path_from(Rails.root)}" do
+      validator = BetterHtml::BetterErb::ErubiImplementation.new(template.read)
+
+      validator.validate!
+    end
+  end
+end

lib/generators/templates/lint/better_html_test.rb

@@ -0,0 +1,17 @@
+require "test_helper"
+
+class ErbImplementationTest < ActiveSupport::TestCase
+  def self.erb_lint
+    configuration = ActiveSupport::ConfigurationFile.parse(".erb-lint.yml")
+
+    ActiveSupport::OrderedOptions.new.merge!(configuration.deep_symbolize_keys!)
+  end
+
+  Rails.root.glob(erb_lint.glob).each do |template|
+    test "html errors in #{template.relative_path_from(Rails.root)}" do
+      validator = BetterHtml::BetterErb::ErubiImplementation.new(template.read)
+
+      validator.validate!
+    end
+  end
+end

lib/generators/templates/lint/config_better_html.yml

@@ -0,0 +1,2 @@
+---
+allow_single_quoted_attributes: false

lib/generators/templates/lint/config_initializers_better_html.rb

@@ -0,0 +1,9 @@
+Rails.configuration.to_prepare do
+  if Rails.env.test?
+    require "better_html"
+
+    BetterHtml.config = BetterHtml::Config.new(Rails.configuration.x.better_html)
+
+    BetterHtml.config.template_exclusion_filter = proc { |filename| !filename.start_with?(Rails.root.to_s) }
+  end
+end

lib/generators/templates/lint/erb-lint.yml

@@ -0,0 +1,63 @@
+---
+glob: "app/views/**/*.{html,turbo_stream}{+*,}.erb"
+
+linters:
+  AllowedScriptType:
+    enabled: true
+    allowed_types:
+      - "module"
+      - "text/javascript"
+  ErbSafety:
+    enabled: true
+    better_html_config: "config/better_html.yml"
+  GitHub::Accessibility::AvoidBothDisabledAndAriaDisabledCounter:
+    enabled: true
+  GitHub::Accessibility::AvoidGenericLinkTextCounter:
+    enabled: true
+  GitHub::Accessibility::DisabledAttributeCounter:
+    enabled: true
+  GitHub::Accessibility::IframeHasTitleCounter:
+    enabled: true
+  GitHub::Accessibility::ImageHasAltCounter:
+    enabled: true
+  GitHub::Accessibility::LandmarkHasLabelCounter:
+    enabled: true
+  GitHub::Accessibility::LinkHasHrefCounter:
+    enabled: true
+  GitHub::Accessibility::NestedInteractiveElementsCounter:
+    enabled: true
+  GitHub::Accessibility::NoAriaLabelMisuseCounter:
+    enabled: true
+  GitHub::Accessibility::NoPositiveTabIndexCounter:
+    enabled: true
+  GitHub::Accessibility::NoRedundantImageAltCounter:
+    enabled: true
+  GitHub::Accessibility::NoTitleAttributeCounter:
+    enabled: true
+  GitHub::Accessibility::SvgHasAccessibleTextCounter:
+    enabled: true
+  Rubocop:
+    enabled: true
+    rubocop_config:
+      inherit_from:
+        - .rubocop.yml
+
+      Lint/EmptyBlock:
+        Enabled: false
+      Layout/InitialIndentation:
+        Enabled: false
+      Layout/TrailingEmptyLines:
+        Enabled: false
+      Layout/TrailingWhitespace:
+        Enabled: false
+      Layout/LeadingEmptyLines:
+        Enabled: false
+      Style/FrozenStringLiteralComment:
+        Enabled: false
+      Style/MultilineTernaryOperator:
+        Enabled: false
+      Lint/UselessAssignment:
+        Exclude:
+          - "app/views/**/*"
+
+EnableDefaultLinters: true

lib/generators/templates/lint/erblint.rake

@@ -0,0 +1,47 @@
+module ERBLint
+  module RakeSupport
+    # Allow command line flags set in STANDARDOPTS (like MiniTest's TESTOPTS)
+    def self.argvify
+      if ENV["ERBLINTOPTS"]
+        ENV["ERBLINTOPTS"].split(/\s+/)
+      else
+        []
+      end
+    end
+
+    # DELETE THIS FILE AFTER MERGE:
+    #
+    #   * https://github.com/Shopify/better-html/pull/95
+    #
+    def self.backport!
+      BetterHtml::TestHelper::SafeErb::AllowedScriptType::VALID_JAVASCRIPT_TAG_TYPES.push("module")
+    end
+  end
+end
+
+desc "Lint templates with erb_lint"
+task "erblint" do
+  require "erb_lint/cli"
+  require "erblint-github/linters"
+
+  ERBLint::RakeSupport.backport!
+
+  cli = ERBLint::CLI.new
+  success = cli.run(ERBLint::RakeSupport.argvify + ["--lint-all", "--format=compact"])
+  fail unless success
+end
+
+desc "Lint and automatically fix templates with erb_lint"
+task "erblint:autocorrect" do
+  require "erb_lint/cli"
+  require "erblint-github/linters"
+
+  ERBLint::RakeSupport.backport!
+
+  cli = ERBLint::CLI.new
+  success = cli.run(ERBLint::RakeSupport.argvify + ["--lint-all", "--autocorrect"])
+  fail unless success
+end
+
+task "standard" => "erblint"
+task "standard:fix" => "erblint:autocorrect"

lib/generators/templates/lint/eslintrc.json

@@ -0,0 +1,7 @@
+{
+  "extends": ["@thoughtbot/eslint-config/prettier"],
+  "parserOptions": {
+    "ecmaVersion": "latest",
+    "sourceType": "module"
+  }
+}

lib/generators/templates/lint/prettierrc

@@ -0,0 +1,11 @@
+{
+  "singleQuote": true,
+  "overrides": [
+    {
+      "files": ["**/*.css", "**/*.scss", "**/*.html"],
+      "options": {
+        "singleQuote": false
+      }
+    }
+  ]
+}

lib/generators/templates/lint/rubocop.yml.tt

@@ -0,0 +1,7 @@
+AllCops:
+  TargetRubyVersion: <%= RUBY_VERSION %>
+
+require: standard
+
+inherit_gem:
+  standard: config/base.yml

lib/generators/templates/lint/stylelintrc.json

@@ -0,0 +1,3 @@
+{
+  "extends": "@thoughtbot/stylelint-config"
+}