Test installer

This commit adds test coverage for the installer Rake task and application template. The installer is run against a freshly generated Rails app using the version of Rails that is currently loaded. Thus the installer can be tested with different versions of Rails in CI.

Similar to hotwired/stimulus-rails#136.

The motivation is to be able to move these tests from railties, see: rails/rails#49679

Co-authored-by: Jonathan Hefner <jonathan@hefner.pro>

.github/workflows/ci.yml

@@ -29,6 +29,7 @@ jobs:
           rubygems: latest
           bundler-cache: true
 
+      - uses: oven-sh/setup-bun@v1
       - name: Run tests
         id: test
         run: bundle exec rake TESTOPT=-vdc

test/app_helper.rb

@@ -0,0 +1,44 @@
+require "rails"
+require "rails/test_help"
+require "fileutils"
+
+module RailsAppHelpers
+  private
+  def create_new_rails_app(app_dir, options=[])
+    require "rails/generators/rails/app/app_generator"
+    Rails::Generators::AppGenerator.start([app_dir, *options, "--skip-bundle", "--skip-bootsnap", "--quiet"])
+
+    Dir.chdir(app_dir) do
+      gemfile = File.read("Gemfile")
+
+      gemfile.gsub!(/^gem ["']turbo-rails["'].*/, "")
+      gemfile << %(gem "turbo-rails", path: #{File.expand_path("..", __dir__).inspect}\n)
+
+      if Rails::VERSION::PRE == "alpha"
+        gemfile.gsub!(/^gem ["']rails["'].*/, "")
+        gemfile << %(gem "rails", path: #{Gem.loaded_specs["rails"].full_gem_path.inspect}\n)
+      end
+
+      File.write("Gemfile", gemfile)
+
+      run_command("bundle", "install")
+    end
+  end
+
+  def with_new_rails_app(options=[], &block)
+    require "digest/sha1"
+    variant = [RUBY_VERSION, Gem.loaded_specs["rails"].full_gem_path,]
+    app_name = "turbo_test_app_#{Digest::SHA1.hexdigest(variant.to_s)}"
+
+    Dir.mktmpdir do |tmpdir|
+      create_new_rails_app("#{tmpdir}/#{app_name}", *options)
+      Dir.chdir("#{tmpdir}/#{app_name}", &block)
+    end
+  end
+
+  def run_command(*command)
+    Bundler.with_unbundled_env do
+      capture_subprocess_io { system(*command, exception: true) }
+    end
+  end
+end

test/installer_test.rb

@@ -0,0 +1,57 @@
+require 'app_helper'
+
+class InstallerTest < ActiveSupport::TestCase
+  include RailsAppHelpers
+  include ActiveSupport::Testing::Isolation
+
+  test "installer" do
+    with_new_rails_app do
+      if Rails::VERSION::MAJOR >= 7 && File.read("Gemfile").match?(/importmap-rails/)
+        run_command("bin/rails", "importmap:install")
+      end
+      run_command("bin/rails", "turbo:install")
+
+      assert_match %(import "@hotwired/turbo-rails"\n), File.read("app/javascript/application.js")
+
+      if Rails::VERSION::MAJOR >= 7
+        assert_match %(pin "@hotwired/turbo-rails", to: "turbo.min.js"), File.read("config/importmap.rb")
+      else
+        assert_match "@hotwired/turbo-rails", File.read("package.json")
+        assert_match "@hotwired/turbo-rails", File.read("yarn.lock")
+      end
+    end
+  end
+
+  test "installer with no javascript" do
+    with_new_rails_app %w[--skip-javascript] do
+      out, = run_command("bin/rails", "turbo:install")
+
+      assert_match "You must either be running with node (package.json) or importmap-rails (config/importmap.rb) to use this gem.", out
+    end
+  end
+
+  test "installer with pre-existing application.js" do
+    with_new_rails_app do
+      if Rails::VERSION::MAJOR >= 7 && File.read("Gemfile").match?(/importmap-rails/)
+        run_command("bin/rails", "importmap:install")
+      end
+      File.write("app/javascript/application.js", "// pre-existing")
+      run_command("bin/rails", "turbo:install")
+
+      assert_match "// pre-existing", File.read("app/javascript/application.js")
+    end
+  end
+
+  if Gem::Version.new(Rails.version) >= Gem::Version.new("7.1")
+    test "installer with bun" do
+      with_new_rails_app %w[--javascript=bun] do
+        run_command("bin/rails", "javascript:install:bun")
+        run_command("bin/rails", "turbo:install")
+
+        assert_match %(import "@hotwired/turbo-rails"\n), File.read("app/javascript/application.js")
+
+        assert_match "@hotwired/turbo-rails", File.read("package.json")
+      end
+    end
+  end
+end