Extract latest_version string to a constant

Library/Homebrew/formula.rb

@@ -3278,6 +3278,7 @@ class Formula
     def livecheck(&block)
       return @livecheck unless block
 
+      include Homebrew::Livecheck::Constants
       @livecheckable = true
       @livecheck.instance_eval(&block)
     end

Library/Homebrew/livecheck.rb

@@ -1,6 +1,8 @@
 # typed: true
 # frozen_string_literal: true
 
+require "livecheck/constants"
+
 # The {Livecheck} class implements the DSL methods used in a formula's, cask's
 # or resource's `livecheck` block and stores related instance variables. Most
 # of these methods also return the related instance variable when no argument
@@ -142,13 +144,6 @@ class Livecheck
     end
   end
 
-  # Returns a placeholder string that will be replaced with a formula's latest
-  # version in livecheck URLs for its resources.
-  # @return String
-  def latest_version
-    "<FORMULA_LATEST_VERSION>"
-  end
-
   delegate version: :@package_or_resource
   delegate arch: :@package_or_resource
   private :version, :arch

Library/Homebrew/livecheck/constants.rb

@@ -0,0 +1,14 @@
+# typed: true
+# frozen_string_literal: true
+
+module Homebrew
+  module Livecheck
+    # The {Constants} module provides constants that are intended to be used
+    # in `livecheck` block values (e.g. `url`, `regex`).
+    module Constants
+      # A placeholder string used in resource `livecheck` block URLs that will
+      # be replaced with the latest version from the main formula check.
+      LATEST_VERSION = "<FORMULA_LATEST_VERSION>"
+    end
+  end
+end

Library/Homebrew/livecheck/livecheck.rb

@@ -1,6 +1,7 @@
 # typed: true
 # frozen_string_literal: true
 
+require "livecheck/constants"
 require "livecheck/error"
 require "livecheck/livecheck_version"
 require "livecheck/skip_conditions"
@@ -877,7 +878,7 @@ module Homebrew
       checked_urls = []
       # rubocop:disable Metrics/BlockLength
       urls.each_with_index do |original_url, i|
-        url = original_url.gsub(/<FORMULA_LATEST_VERSION>/, formula_latest)
+        url = original_url.gsub(Constants::LATEST_VERSION, formula_latest)
 
         # Only preprocess the URL when it's appropriate
         url = preprocess_url(url) unless STRATEGY_SYMBOLS_TO_SKIP_PREPROCESS_URL.include?(livecheck_strategy)