Tap: add untapped_official_taps method

Library/Homebrew/brew.rb

@@ -132,8 +132,7 @@ begin
     possible_tap = OFFICIAL_CMD_TAPS.find { |_, cmds| cmds.include?(cmd) }
     possible_tap = Tap.fetch(possible_tap.first) if possible_tap
 
-    untapped_official_taps = Homebrew::Settings.read(:untapped)&.split(";") || []
-    if !possible_tap || possible_tap.installed? || untapped_official_taps.include?(possible_tap.name)
+    if !possible_tap || possible_tap.installed? || Tap.untapped_official_taps.include?(possible_tap.name)
       odie "Unknown command: #{cmd}"
     end
 

Library/Homebrew/extend/os/mac/tap.rb

@@ -5,8 +5,7 @@ class Tap
   def self.install_default_cask_tap_if_necessary
     return false if default_cask_tap.installed?
 
-    untapped_official_taps = Homebrew::Settings.read(:untapped)&.split(";") || []
-    return false if untapped_official_taps.include?(default_cask_tap.name)
+    return false if Tap.untapped_official_taps.include?(default_cask_tap.name)
 
     default_cask_tap.install
     true

Library/Homebrew/tap.rb

@@ -327,7 +327,7 @@ class Tap
     end
 
     if official?
-      untapped = Homebrew::Settings.read(:untapped)&.split(";") || []
+      untapped = self.class.untapped_official_taps
       untapped -= [name]
 
       if untapped.empty?
@@ -388,8 +388,7 @@ class Tap
 
     return unless official?
 
-    untapped = Homebrew::Settings.read(:untapped)&.split(";") || []
-
+    untapped = self.class.untapped_official_taps
     return if untapped.include? name
 
     untapped << name
@@ -644,6 +643,12 @@ class Tap
     Pathname.glob TAP_DIRECTORY/"*/*/cmd"
   end
 
+  # An array of official taps that have been manually untapped
+  sig { returns(T::Array[String]) }
+  def self.untapped_official_taps
+    Homebrew::Settings.read(:untapped)&.split(";") || []
+  end
+
   # @private
   def formula_file_to_name(file)
     "#{name}/#{file.basename(".rb")}"