Refactor `brew cask style` not to require `.rubocop.yml`.

Library/Homebrew/cask/lib/hbc/cli/style.rb

@@ -54,17 +54,17 @@ module Hbc
       end
 
       def default_args
-        ["--format", "simple", "--force-exclusion", "--config", rubocop_config]
+        [
+          "--require", "rubocop-cask",
+          "--format", "simple",
+          "--force-exclusion"
+        ]
       end
 
       def autocorrect_args
         default_args + ["--auto-correct"]
       end
 
-      def rubocop_config
-        Hbc.default_tap.cask_dir.join(".rubocop.yml")
-      end
-
       def fix?
         args.any? { |arg| arg =~ %r{--(fix|(auto-?)?correct)} }
       end

Library/Homebrew/cask/spec/cask/cli/style_spec.rb

@@ -175,12 +175,8 @@ describe Hbc::CLI::Style do
 
   describe "#default_args" do
     subject { cli.default_args }
-    let(:rubocop_config) { ".rubocop.yml" }
-    before do
-      allow(cli).to receive(:rubocop_config).and_return(rubocop_config)
-    end
 
-    it { is_expected.to include("--format", "simple", "--force-exclusion", "--config", rubocop_config) }
+    it { is_expected.to include("--require", "rubocop-cask", "--format", "simple", "--force-exclusion") }
   end
 
   describe "#autocorrect_args" do