download_strategy: allow to suppress output

Library/Homebrew/download_strategy.rb

@@ -6,6 +6,7 @@ class AbstractDownloadStrategy
   include FileUtils
 
   attr_reader :meta, :name, :version, :resource
+  attr_reader :shutup
 
   def initialize(name, resource)
     @name = name
@@ -19,6 +20,19 @@ class AbstractDownloadStrategy
   def fetch
   end
 
+  # Supress output
+  def shutup!
+    @shutup = true
+  end
+
+  def puts(*args)
+    super(*args) unless shutup
+  end
+
+  def ohai(*args)
+    super(*args) unless shutup
+  end
+
   # Unpack {#cached_location} into the current working directory, and possibly
   # chdir into the newly-unpacked directory.
   # Unlike {Resource#stage}, this does not take a block.
@@ -59,6 +73,14 @@ class AbstractDownloadStrategy
     args
   end
 
+  def safe_system(*args)
+    if @shutup
+      quiet_system(*args) || raise(ErrorDuringExecution.new(args.shift, *args))
+    else
+      super(*args)
+    end
+  end
+
   def quiet_safe_system(*args)
     safe_system(*expand_safe_system_args(args))
   end