Optimize test suite duration by caching test infrastructure (#4004)

* Add autoresearch setup for test duration optimization

* Cache GlobalState and RuboCopFormatter in expectation tests

Reduces test_duration from ~454s to ~301s (33% improvement)

* Skip addon loading in Definition and Hover expectation tests

Addon loading (especially RuboCop addon) costs ~103ms per test.
Generated expectation tests don't need addons, only the hand-written
tests that explicitly test addon behavior do.

Reduces test_duration from ~301s to ~217s (28% improvement).

* Default load_addons: false for Definition and Hover test classes

Most hand-written tests in these classes don't need addons.
Only test_definition_addons and test_hover_addons explicitly enable
addon loading. Saves ~3s from avoiding ~79 addon activation cycles.

* Update autoresearch.md with latest findings

* Remove autoresearch scaffolding files

* Fix cspell: use 'add-on' in comments instead of 'addon'

Author: st0012

test/requests/definition_expectations_test.rb

@@ -7,6 +7,12 @@
 class DefinitionExpectationsTest < ExpectationsTestRunner
   expectations_tests RubyLsp::Requests::Definition, "definition"
 
+  # Skip add-on loading by default — only test_definition_addons needs it
+  def with_server(source = nil, uri = Kernel.URI("file:///fake.rb"), stub_no_typechecker: false, load_addons: false,
+    &block)
+    super
+  end
+
   def run_expectations(source)
     # We need to pretend that Sorbet is not a dependency or else we can't properly test
     with_server(source, stub_no_typechecker: true) do |server, uri|
@@ -229,7 +235,7 @@ def test_definition_addons
     begin
       create_definition_addon
 
-      with_server(source, stub_no_typechecker: true) do |server, uri|
+      with_server(source, stub_no_typechecker: true, load_addons: true) do |server, uri|
         server.global_state.index.index_file(
           URI::Generic.from_path(
             load_path_entry: "#{Dir.pwd}/lib",

test/requests/diagnostics_expectations_test.rb

@@ -14,7 +14,7 @@ def run_expectations(source)
     })
     @global_state.register_formatter(
       "rubocop_internal",
-      RubyLsp::Requests::Support::RuboCopFormatter.new,
+      self.class.cached_rubocop_formatter,
     )
 
     document = RubyLsp::RubyDocument.new(
@@ -81,4 +81,10 @@ def map_diagnostics(diagnostics)
       )
     end.to_json
   end
+
+  class << self
+    def cached_rubocop_formatter
+      @cached_rubocop_formatter ||= RubyLsp::Requests::Support::RuboCopFormatter.new
+    end
+  end
 end

test/requests/formatting_expectations_test.rb

@@ -11,7 +11,7 @@ def run_expectations(source)
     @global_state.formatter = "rubocop_internal"
     @global_state.register_formatter(
       "rubocop_internal",
-      RubyLsp::Requests::Support::RuboCopFormatter.new,
+      self.class.cached_rubocop_formatter,
     )
     document = RubyLsp::RubyDocument.new(
       source: source,
@@ -37,4 +37,10 @@ def assert_expectations(source, expected)
 
   def initialize_params(_expected)
   end
+
+  class << self
+    def cached_rubocop_formatter
+      @cached_rubocop_formatter ||= RubyLsp::Requests::Support::RuboCopFormatter.new
+    end
+  end
 end

test/requests/hover_expectations_test.rb

@@ -7,6 +7,12 @@
 class HoverExpectationsTest < ExpectationsTestRunner
   expectations_tests RubyLsp::Requests::Hover, "hover"
 
+  # Skip add-on loading by default — only test_hover_addons needs it
+  def with_server(source = nil, uri = Kernel.URI("file:///fake.rb"), stub_no_typechecker: false, load_addons: false,
+    &block)
+    super
+  end
+
   def run_expectations(source)
     position = @__params&.first || { character: 0, line: 0 }
 
@@ -356,7 +362,7 @@ class Post
     begin
       create_hover_addon
 
-      with_server(source, stub_no_typechecker: true) do |server, uri|
+      with_server(source, stub_no_typechecker: true, load_addons: true) do |server, uri|
         server.process_message(
           id: 1,
           method: "textDocument/hover",

test/requests/support/expectations_test_runner.rb

@@ -8,10 +8,14 @@ class ExpectationsTestRunner < Minitest::Test
   TEST_PRISM_FIXTURES = File.join(TEST_FIXTURES_DIR, "prism/test/prism/fixtures/**", "*.txt")
 
   def setup
-    @global_state = RubyLsp::GlobalState.new
+    @global_state = self.class.shared_global_state
   end
 
   class << self
+    def shared_global_state
+      @shared_global_state ||= RubyLsp::GlobalState.new
+    end
+
     def expectations_tests(handler_class, expectation_suffix)
       class_eval(<<~RB, __FILE__, __LINE__ + 1)
         module ExpectationsRunnerMethods