tap_auditor: add comprehensive validation for formula and cask renames

Library/Homebrew/tap_auditor.rb

@@ -4,7 +4,7 @@
 module Homebrew
   # Auditor for checking common violations in {Tap}s.
   class TapAuditor
-    attr_reader :name, :path, :formula_names, :formula_aliases, :formula_renames, :cask_tokens,
+    attr_reader :name, :path, :formula_names, :formula_aliases, :formula_renames, :cask_tokens, :cask_renames,
                 :tap_audit_exceptions, :tap_style_exceptions, :problems
 
     sig { params(tap: Tap, strict: T.nilable(T::Boolean)).void }
@@ -27,6 +27,7 @@ def initialize(tap, strict:)
           formula_alias.split("/").last
         end
         @formula_renames = tap.formula_renames
+        @cask_renames = tap.cask_renames
         @formula_names = tap.formula_names.map do |formula_name|
           formula_name.split("/").last
         end
@@ -54,7 +55,8 @@ def audit_json_files
     def audit_tap_formula_lists
       check_formula_list_directory "audit_exceptions", @tap_audit_exceptions
       check_formula_list_directory "style_exceptions", @tap_style_exceptions
-      check_formula_list "formula_renames", @formula_renames.values
+      check_renames "formula_renames.json", @formula_renames, @formula_names, @formula_aliases
+      check_renames "cask_renames.json", @cask_renames, @cask_tokens
       check_formula_list ".github/autobump.txt", @tap_autobump unless @tap_official
       check_formula_list "synced_versions_formulae", @tap_synced_versions_formulae.flatten
     end
@@ -107,5 +109,78 @@ def check_formula_list_directory(directory_name, lists)
         check_formula_list "#{directory_name}/#{list_name}", list
       end
     end
+
+    sig {
+      params(list_file: String, renames_hash: T::Hash[String, String], valid_tokens: T::Array[String],
+             valid_aliases: T::Array[String]).void
+    }
+    def check_renames(list_file, renames_hash, valid_tokens, valid_aliases = [])
+      item_type = list_file.include?("cask") ? "casks" : "formulae"
+
+      # Collect all validation issues in a single pass
+      invalid_format_entries = []
+      invalid_targets = []
+      chained_rename_suggestions = []
+      conflicts = []
+
+      renames_hash.each do |old_name, new_name|
+        # Check for .rb extensions
+        if old_name.end_with?(".rb") || new_name.end_with?(".rb")
+          invalid_format_entries << "\"#{old_name}\": \"#{new_name}\""
+        end
+
+        # Check that new name exists
+        if valid_tokens.exclude?(new_name) && valid_aliases.exclude?(new_name) && !renames_hash.key?(new_name)
+          invalid_targets << new_name
+        end
+
+        # Check for chained renames and follow to final target
+        if renames_hash.key?(new_name)
+          final = new_name
+          seen = Set.new([old_name, new_name])
+          while renames_hash.key?(final)
+            next_name = renames_hash[final]
+            break if next_name.nil? || seen.include?(next_name)
+
+            final = next_name
+            seen << final
+          end
+          chained_rename_suggestions << "  \"#{old_name}\": \"#{final}\" (instead of chained rename)"
+        end
+
+        # Check for conflicts
+        conflicts << old_name if valid_tokens.include?(old_name)
+      end
+
+      if invalid_format_entries.any?
+        problem <<~EOS
+          #{list_file} contains entries with '.rb' file extensions.
+          Rename entries should use formula/cask names only, without '.rb' extensions.
+          Invalid entries: #{invalid_format_entries.join(", ")}
+        EOS
+      end
+
+      if invalid_targets.any?
+        problem <<~EOS
+          #{list_file} contains renames to #{item_type} that do not exist in the #{@name} tap.
+          Invalid targets: #{invalid_targets.join(", ")}
+        EOS
+      end
+
+      if chained_rename_suggestions.any?
+        problem <<~EOS
+          #{list_file} contains chained renames that should be collapsed.
+          Chained renames don't work automatically; each old name should point directly to the final target:
+          #{chained_rename_suggestions.join("\n")}
+        EOS
+      end
+
+      return if conflicts.none?
+
+      problem <<~EOS
+        #{list_file} contains old names that conflict with existing #{item_type} in the #{@name} tap.
+        Renames only work after the old #{item_type} are deleted. Conflicting names: #{conflicts.join(", ")}
+      EOS
+    end
   end
 end