ARGV: extract #values from missing

Library/Homebrew/cmd/missing.rb

@@ -18,10 +18,8 @@ module Homebrew
       ARGV.resolved_formulae
     end
 
-    hide = (ARGV.value("hide") || "").split(",")
-
     ff.each do |f|
-      missing = f.missing_dependencies(hide: hide)
+      missing = f.missing_dependencies(hide: ARGV.values("hide"))
       next if missing.empty?
 
       print "#{f}: " if ff.size > 1

Library/Homebrew/extend/ARGV.rb

@@ -121,6 +121,13 @@ module HomebrewArgvExtension
     flag_with_value.strip_prefix(arg_prefix) if flag_with_value
   end
 
+  # Returns an array of values that were given as a comma-seperated list.
+  # @see value
+  def values(name)
+    return unless val = value(name)
+    val.split(",")
+  end
+
   def force?
     flag? "--force"
   end

Library/Homebrew/test/test_ARGV.rb

@@ -62,4 +62,19 @@ class ArgvExtensionTests < Homebrew::TestCase
     assert !@argv.flag?("--frotz")
     assert !@argv.flag?("--debug")
   end
+
+  def test_value
+    @argv << "--foo=" << "--bar=ab"
+    assert_equal "", @argv.value("foo")
+    assert_equal "ab", @argv.value("bar")
+    assert_nil @argv.value("baz")
+  end
+
+  def test_values
+    @argv << "--foo=" << "--bar=a" << "--baz=b,c"
+    assert_equal [], @argv.values("foo")
+    assert_equal ["a"], @argv.values("bar")
+    assert_equal ["b", "c"], @argv.values("baz")
+    assert_nil @argv.values("qux")
+  end
 end