Consolidate RuboCop feature loading

Closes #2604
Alternative to #2605

This moves the two command CI checks into the test suite.
They would have cought this error, _expect_ rubocop is available to these.
So, create a seperate Gemfile that contains only the gem itself.

.github/workflows/ci.yml

@@ -43,9 +43,6 @@ jobs:
 
       - name: Run tests
         run: bundle exec rake
-
-      - name: Run index troubleshooting tool
-        run: bundle exec ruby-lsp --doctor
   lint_node:
     runs-on: ubuntu-latest
     steps:

lib/ruby_lsp/internal.rb

@@ -47,15 +47,13 @@
 require "ruby_lsp/response_builders/signature_help"
 
 # Request support
-require "ruby_lsp/requests/support/rubocop_diagnostic"
 require "ruby_lsp/requests/support/selection_range"
 require "ruby_lsp/requests/support/annotation"
 require "ruby_lsp/requests/support/sorbet"
 require "ruby_lsp/requests/support/common"
 require "ruby_lsp/requests/support/formatter"
-require "ruby_lsp/requests/support/rubocop_runner"
-require "ruby_lsp/requests/support/rubocop_formatter"
 require "ruby_lsp/requests/support/syntax_tree_formatter"
+require "ruby_lsp/requests/support/rubocop"
 
 # Requests
 require "ruby_lsp/requests/request"

lib/ruby_lsp/requests/support/rubocop.rb

@@ -0,0 +1,22 @@
+# typed: strict
+# frozen_string_literal: true
+
+begin
+  require "rubocop"
+rescue LoadError
+  return
+end
+
+begin
+  gem("rubocop", ">= 1.4.0")
+rescue LoadError
+  raise StandardError, "Incompatible RuboCop version. Ruby LSP requires >= 1.4.0"
+end
+
+if RuboCop.const_defined?(:LSP) # This condition will be removed when requiring RuboCop >= 1.61.
+  RuboCop::LSP.enable
+end
+
+require "ruby_lsp/requests/support/rubocop_diagnostic"
+require "ruby_lsp/requests/support/rubocop_runner"
+require "ruby_lsp/requests/support/rubocop_formatter"

lib/ruby_lsp/requests/support/rubocop_formatter.rb

@@ -1,8 +1,6 @@
 # typed: strict
 # frozen_string_literal: true
 
-return unless defined?(RubyLsp::Requests::Support::RuboCopRunner)
-
 module RubyLsp
   module Requests
     module Support

lib/ruby_lsp/requests/support/rubocop_runner.rb

@@ -1,22 +1,6 @@
 # typed: strict
 # frozen_string_literal: true
 
-begin
-  require "rubocop"
-rescue LoadError
-  return
-end
-
-begin
-  gem("rubocop", ">= 1.4.0")
-rescue LoadError
-  raise StandardError, "Incompatible RuboCop version. Ruby LSP requires >= 1.4.0"
-end
-
-if RuboCop.const_defined?(:LSP) # This condition will be removed when requiring RuboCop >= 1.61.
-  RuboCop::LSP.enable
-end
-
 module RubyLsp
   module Requests
     module Support

test/integration_test.rb

@@ -0,0 +1,44 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+
+class IntegrationTest < Minitest::Test
+  def test_ruby_lsp_doctor_works
+    skip("CI only") unless ENV["CI"]
+    in_isolation do
+      system("bundle exec ruby-lsp --doctor")
+      assert_equal(0, $CHILD_STATUS)
+    end
+  end
+
+  def test_ruby_lsp_check_works
+    skip("CI only") unless ENV["CI"]
+    in_isolation do
+      system("bundle exec ruby-lsp-check")
+      assert_equal(0, $CHILD_STATUS)
+    end
+  end
+
+  private
+
+  def in_isolation(&block)
+    gem_path = T.must(__dir__) + "/../"
+    Dir.mktmpdir do |dir|
+      Dir.chdir(dir) do
+        File.write(File.join(dir, "Gemfile"), <<~GEMFILE)
+          source "https://rubygems.org"
+          gem "ruby-lsp", path: "#{gem_path}"
+
+          # This causes ruby-lsp to run in its own directory without
+          # all the supplementary gems like rubocop
+          Dir.chdir("#{gem_path}")
+        GEMFILE
+
+        capture_subprocess_io do
+          Bundler.with_unbundled_env(&block)
+        end
+      end
+    end
+  end
+end