cask audit: check for `latest` with `auto_updates`

Library/Homebrew/cask/lib/hbc/audit.rb

@@ -36,6 +36,7 @@ module Hbc
       check_untrusted_pkg
       check_hosting_with_appcast
       check_latest_with_appcast
+      check_latest_with_auto_updates
       check_stanza_requires_uninstall
       self
     rescue StandardError => e
@@ -199,6 +200,13 @@ module Hbc
       add_warning "Casks with an appcast should not use version :latest"
     end
 
+    def check_latest_with_auto_updates
+      return unless cask.version.latest?
+      return unless cask.auto_updates
+
+      add_warning "Casks with `version :latest` should not use `auto_updates`"
+    end
+
     def check_hosting_with_appcast
       return if cask.appcast
 

Library/Homebrew/test/cask/audit_spec.rb

@@ -413,6 +413,34 @@ describe Hbc::Audit, :cask do
       end
     end
 
+    describe "latest with auto_updates checks" do
+      let(:warning_msg) { "Casks with `version :latest` should not use `auto_updates`" }
+
+      context "when the Cask is :latest and does not have auto_updates" do
+        let(:cask_token) { "version-latest" }
+
+        it { is_expected.not_to warn_with(warning_msg) }
+      end
+
+      context "when the Cask is versioned and does not have auto_updates" do
+        let(:cask_token) { "basic-cask" }
+
+        it { is_expected.not_to warn_with(warning_msg) }
+      end
+
+      context "when the Cask is versioned and has auto_updates" do
+        let(:cask_token) { "auto-updates" }
+
+        it { is_expected.not_to warn_with(warning_msg) }
+      end
+
+      context "when the Cask is :latest and has auto_updates" do
+        let(:cask_token) { "latest-with-auto-updates" }
+
+        it { is_expected.to warn_with(warning_msg) }
+      end
+    end
+
     describe "preferred download URL formats" do
       let(:warning_msg) { /URL format incorrect/ }
 

Library/Homebrew/test/support/fixtures/cask/Casks/latest-with-auto-updates.rb

+cask 'latest-with-auto-updates' do
+  version :latest
+  sha256 :no_check
+
+  url "file://#{TEST_FIXTURE_DIR}/cask/caffeine.zip"
+  homepage 'http://example.com/latest-with-auto-updates'
+
+  auto_updates true
+
+  app 'Caffeine.app'
+end