rubocops/livecheck: Rework LivecheckUrlProvided

The existing `LivecheckUrlProvided` RuboCop requires a `url` for all
`livecheck` blocks except those using `skip`, `formula`, or `cask`,
as those only appear in a `livecheck` block with no other DSL methods.

We now have a `throttle` method that can be used alongside other DSL
methods (e.g., `url`, `regex`, `strategy`) or by itself. `brew style`
currently fails when `throttle` is used by itself, so this reworks
the conditions to allow this usage.

Library/Homebrew/rubocops/livecheck.rb

@@ -45,20 +45,19 @@ def audit_formula(_node, _class_node, _parent_class_node, body_node)
  class LivecheckUrlProvided < FormulaCop
  def audit_formula(_node, _class_node, _parent_class_node, body_node)
  livecheck_node = find_block(body_node, :livecheck)
- return if livecheck_node.blank?
-
- skip = find_every_method_call_by_name(livecheck_node, :skip).first
- return if skip.present?
+ return unless livecheck_node
 
- formula_node = find_every_method_call_by_name(livecheck_node, :formula).first
- cask_node = find_every_method_call_by_name(livecheck_node, :cask).first
- return if formula_node.present? || cask_node.present?
+ url_node = find_every_method_call_by_name(livecheck_node, :url).first
+ return if url_node
 
- livecheck_url = find_every_method_call_by_name(livecheck_node, :url).first
- return if livecheck_url.present?
+ # A regex and/or strategy is specific to a particular URL, so we
+ # should require an explicit URL.
+ regex_node = find_every_method_call_by_name(livecheck_node, :regex).first
+ strategy_node = find_every_method_call_by_name(livecheck_node, :strategy).first
+ return if !regex_node && !strategy_node
 
  offending_node(livecheck_node)
- problem "A `url` must be provided to livecheck."
+ problem "A `url` should be provided when `regex` or `strategy` are used."
  end
  end
 

Library/Homebrew/test/rubocops/livecheck/url_provided_spec.rb

@@ -5,20 +5,31 @@
 RSpec.describe RuboCop::Cop::FormulaAudit::LivecheckUrlProvided do
  subject(:cop) { described_class.new }
 
- it "reports an offense when a `url` is not specified in the livecheck block" do
+ it "reports an offense when a `url` is not specified in a livecheck block" do
  expect_offense(<<~RUBY)
  class Foo < Formula
  url "https://brew.sh/foo-1.0.tgz"
 
  livecheck do
- ^^^^^^^^^^^^ FormulaAudit/LivecheckUrlProvided: A `url` must be provided to livecheck.
+ ^^^^^^^^^^^^ FormulaAudit/LivecheckUrlProvided: A `url` should be provided when `regex` or `strategy` are used.
  regex(%r{href=.*?/formula[._-]v?(\\d+(?:\\.\\d+)+)\\.t}i)
  end
  end
  RUBY
+
+ expect_offense(<<~RUBY)
+ class Foo < Formula
+ url "https://brew.sh/foo-1.0.tgz"
+
+ livecheck do
+ ^^^^^^^^^^^^ FormulaAudit/LivecheckUrlProvided: A `url` should be provided when `regex` or `strategy` are used.
+ strategy :page_match
+ end
+ end
+ RUBY
  end
 
- it "reports no offenses when a `url` is specified in the livecheck block" do
+ it "reports no offenses when a `url` and `regex` are specified in the livecheck block" do
  expect_no_offenses(<<~RUBY)
  class Foo < Formula
  url "https://brew.sh/foo-1.0.tgz"
@@ -30,4 +41,17 @@ class Foo < Formula
  end
  RUBY
  end
+
+ it "reports no offenses when a `url` and `strategy` are specified in the livecheck block" do
+ expect_no_offenses(<<~RUBY)
+ class Foo < Formula
+ url "https://brew.sh/foo-1.0.tgz"
+
+ livecheck do
+ url :stable
+ strategy :page_match
+ end
+ end
+ RUBY
+ end
 end