Merge pull request #18012 from apainintheneck/verify-more-constants-n…

…ot-loaded-at-startup

Verify more constants are not loaded at startup

Library/Homebrew/test/global_spec.rb

@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
 RSpec.describe Homebrew, :integration_test do
-  it "does not invoke `require \"formula\"` at startup" do
-    expect { brew "verify-formula-undefined" }
+  it "does not require slow dependencies at startup" do
+    expect { brew "verify-undefined" }
       .to not_to_output.to_stdout
       .and not_to_output.to_stderr
       .and be_a_success

Library/Homebrew/test/support/helper/cmd/brew-verify-undefined.rb

@@ -0,0 +1,40 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "cli/parser"
+
+UNDEFINED_CONSTANTS = %w[
+  Cask::Cask
+  Formula
+  Formulary
+  Homebrew::API
+  Tap
+].freeze
+
+module Homebrew
+  module Cmd
+    class VerifyUndefined < AbstractCommand
+    end
+  end
+end
+
+parser = Homebrew::CLI::Parser.new(Homebrew::Cmd::VerifyUndefined) do
+  usage_banner <<~EOS
+    `verify-undefined`
+
+    Verifies that the following constants have not been defined
+    at startup to make sure that startup times stay consistent.
+
+    Contants:
+    #{UNDEFINED_CONSTANTS.join("\n")}
+  EOS
+end
+
+parser.parse
+
+UNDEFINED_CONSTANTS.each do |constant_name|
+  Object.const_get(constant_name)
+  ofail "#{constant_name} should not be defined at startup"
+rescue NameError
+  # We expect this to error as it should not be defined.
+end