rubocops/cask: Disallow protocol in cask URL verified stanza

- Apparently the "verified" parameter in the URL (present when a Cask's
  download URL is not the same as its homepage) shouldn't have the
  protocol (`https`, `http`) at the front.
- Removing this has happened manually in the past, so here's an
  autocorrecting RuboCop for it.

Library/Homebrew/rubocops/cask/url.rb

@@ -0,0 +1,37 @@
+# typed: true
+# frozen_string_literal: true
+
+require "forwardable"
+
+module RuboCop
+  module Cop
+    module Cask
+      # This cop checks that a cask's `url` stanza is formatted correctly.
+      class Url < Base
+        extend AutoCorrector
+        extend Forwardable
+        include OnUrlStanza
+
+        def on_url_stanza(stanza)
+          return if stanza.stanza_node.block_type?
+
+          hash_node = stanza.stanza_node.last_argument
+          return unless hash_node.hash_type?
+
+          hash_node.each_pair do |key_node, value_node|
+            next unless key_node.source == "verified"
+            next unless value_node.str_type?
+            next unless value_node.source.start_with?("\"https:/", "\"http:/")
+
+            add_offense(
+              value_node.source_range,
+              message: "Verified URL parameter value should not start with https:// or http://.",
+            ) do |corrector|
+              corrector.replace(value_node.source_range, value_node.source.gsub(%r{^"https?://}, "\""))
+            end
+          end
+        end
+      end
+    end
+  end
+end

Library/Homebrew/rubocops/rubocop-cask.rb

@@ -18,5 +18,6 @@
 require_relative "cask/on_system_conditionals"
 require_relative "cask/stanza_order"
 require_relative "cask/stanza_grouping"
+require_relative "cask/url"
 require_relative "cask/url_legacy_comma_separators"
 require_relative "cask/variables"

Library/Homebrew/test/rubocops/cask/url_spec.rb

@@ -0,0 +1,47 @@
+# typed: false
+# frozen_string_literal: true
+
+require "rubocops/rubocop-cask"
+require "test/rubocops/cask/shared_examples/cask_cop"
+
+describe RuboCop::Cop::Cask::Url do
+  include CaskCop
+
+  subject(:cop) { described_class.new }
+
+  context "when url 'verified' value does not start with a protocol" do
+    let(:source) do
+      <<~CASK
+        cask "foo" do
+          url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "example.com"
+        end
+      CASK
+    end
+
+    include_examples "does not report any offenses"
+  end
+
+  context "when url 'verified' value starts with a protocol" do
+    let(:source) do
+      <<~CASK
+        cask "foo" do
+          url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "https://example.com"
+        end
+      CASK
+    end
+
+    let(:expected_offenses) do
+      [{
+        message:  "Verified URL parameter value should not start with https:// or http://.",
+        severity: :convention,
+        line:     3,
+        column:   4,
+        source:   "verified: \"https://example.com\"",
+      }]
+    end
+
+    include_examples "reports offenses"
+  end
+end