Use extend/os pattern.

Library/Homebrew/cmd/search.rb

@@ -18,7 +18,6 @@ require "missing_formula"
 require "descriptions"
 require "cli_parser"
 require "search"
-require "hbc/cask_loader"
 
 module Homebrew
   module_function
@@ -63,38 +62,13 @@ module Homebrew
       query = args.remaining.join(" ")
       string_or_regex = query_regexp(query)
 
-      remote_results = if query.match?(HOMEBREW_TAP_FORMULA_REGEX) || query.match?(HOMEBREW_TAP_CASK_REGEX)
-        _, _, name = query.split("/", 3)
-        search_taps(name, silent: true)
-      else
-        search_taps(query, silent: true)
-      end
-
-      local_formulae = if query.match?(HOMEBREW_TAP_FORMULA_REGEX)
-        begin
-          [Formulary.factory(query).name]
-        rescue FormulaUnavailableError
-          []
-        end
-      else
-        search_formulae(string_or_regex)
-      end
+      remote_results = search_taps(query, silent: true)
 
+      local_formulae = search_formulae(string_or_regex)
       remote_formulae = remote_results[:formulae]
       all_formulae = local_formulae + remote_formulae
 
-      local_casks = if !OS.mac?
-        []
-      elsif query.match?(HOMEBREW_TAP_CASK_REGEX)
-        begin
-          [Hbc::CaskLoader.load(query).token]
-        rescue Hbc::CaskUnavailableError
-          []
-        end
-      else
-        search_casks(string_or_regex)
-      end
-
+      local_casks = search_casks(string_or_regex)
       remote_casks = remote_results[:casks]
       all_casks = local_casks + remote_casks
 

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

@@ -0,0 +1,26 @@
+require "hbc/cask"
+require "hbc/cask_loader"
+
+module Homebrew
+  module Search
+    def search_casks(string_or_regex)
+      if string_or_regex.is_a?(String) && string_or_regex.match?(HOMEBREW_TAP_CASK_REGEX)
+        return begin
+          [Hbc::CaskLoader.load(string_or_regex).token]
+        rescue Hbc::CaskUnavailableError
+          []
+        end
+      end
+
+      results = Hbc::Cask.search(string_or_regex, &:token).sort_by(&:token)
+
+      results.map do |cask|
+        if cask.installed?
+          pretty_installed(cask.token)
+        else
+          cask.token
+        end
+      end
+    end
+  end
+end

Library/Homebrew/extend/os/search.rb

@@ -0,0 +1 @@
+require "extend/os/mac/search" if OS.mac?

Library/Homebrew/search.rb

@@ -1,5 +1,4 @@
 require "searchable"
-require "hbc/cask"
 
 module Homebrew
   module Search
@@ -14,6 +13,10 @@ module Homebrew
     end
 
     def search_taps(query, silent: false)
+      if query.match?(Regexp.union(HOMEBREW_TAP_FORMULA_REGEX, HOMEBREW_TAP_CASK_REGEX))
+        _, _, query = query.split("/", 3)
+      end
+
       results = { formulae: [], casks: [] }
 
       return results if ENV["HOMEBREW_NO_GITHUB_API"]
@@ -53,6 +56,14 @@ module Homebrew
     end
 
     def search_formulae(string_or_regex)
+      if string_or_regex.is_a?(String) && string_or_regex.match?(HOMEBREW_TAP_FORMULA_REGEX)
+        return begin
+          [Formulary.factory(string_or_regex).name]
+        rescue FormulaUnavailableError
+          []
+        end
+      end
+
       aliases = Formula.alias_full_names
       results = (Formula.full_names + aliases)
                 .extend(Searchable)
@@ -78,16 +89,10 @@ module Homebrew
       end.compact
     end
 
-    def search_casks(string_or_regex)
-      results = Hbc::Cask.search(string_or_regex, &:token).sort_by(&:token)
-
-      results.map do |cask|
-        if cask.installed?
-          pretty_installed(cask.token)
-        else
-          cask.token
-        end
-      end
+    def search_casks(_string_or_regex)
+      []
     end
   end
 end
+
+require "extend/os/search"