Move SimulateSystem check to extend/os

Library/Homebrew/extend/os/linux/simulate_system.rb

@@ -0,0 +1,29 @@
+# typed: true
+# frozen_string_literal: true
+
+module Homebrew
+  class SimulateSystem
+    class << self
+      undef os
+      undef simulating_or_running_on_linux?
+      undef current_os
+
+      sig { returns(T.nilable(Symbol)) }
+      def os
+        return :macos if @os.blank? && Homebrew::EnvConfig.simulate_macos_on_linux?
+
+        @os
+      end
+
+      sig { returns(T::Boolean) }
+      def simulating_or_running_on_linux?
+        os.blank? || os == :linux
+      end
+
+      sig { returns(Symbol) }
+      def current_os
+        os || :linux
+      end
+    end
+  end
+end

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

@@ -0,0 +1,21 @@
+# typed: true
+# frozen_string_literal: true
+
+module Homebrew
+  class SimulateSystem
+    class << self
+      undef simulating_or_running_on_macos?
+      undef current_os
+
+      sig { returns(T::Boolean) }
+      def simulating_or_running_on_macos?
+        os.blank? || [:macos, *MacOSVersions::SYMBOLS.keys].include?(os)
+      end
+
+      sig { returns(Symbol) }
+      def current_os
+        os || MacOS.version.to_sym
+      end
+    end
+  end
+end

Library/Homebrew/extend/os/simulate_system.rb

@@ -0,0 +1,8 @@
+# typed: strict
+# frozen_string_literal: true
+
+if OS.mac?
+  require "extend/os/mac/simulate_system"
+elsif OS.linux?
+  require "extend/os/linux/simulate_system"
+end

Library/Homebrew/simulate_system.rb

@@ -9,14 +9,7 @@ module Homebrew
     class << self
       extend T::Sig
 
-      attr_reader :arch
+      attr_reader :arch, :os
-
-      sig { returns(T.nilable(Symbol)) }
-      def os
-        return :macos if @os.blank? && !OS.mac? && Homebrew::EnvConfig.simulate_macos_on_linux?
-
-        @os
-      end
 
       sig { params(new_os: Symbol).void }
       def os=(new_os)
@@ -40,15 +33,11 @@ module Homebrew
 
       sig { returns(T::Boolean) }
       def simulating_or_running_on_macos?
-        return OS.mac? if os.blank?
-
         [:macos, *MacOSVersions::SYMBOLS.keys].include?(os)
       end
 
       sig { returns(T::Boolean) }
       def simulating_or_running_on_linux?
-        return OS.linux? if os.blank?
-
         os == :linux
       end
 
@@ -59,11 +48,10 @@ module Homebrew
 
       sig { returns(Symbol) }
       def current_os
-        return T.must(os) if os.present?
+        os || :generic
-        return :linux if OS.linux?
+      end
+    end
+  end
+end
 
-        MacOS.version.to_sym
+require "extend/os/simulate_system"
-      end
-    end
-  end
-end