Add stubs for sorbet-runtime.

Library/Homebrew/utils.rb

@@ -12,6 +12,7 @@ require "utils/link"
 require "utils/livecheck_formula"
 require "utils/popen"
 require "utils/repology"
+require "utils/sorbet"
 require "utils/svn"
 require "utils/tty"
 require "tap_constants"

Library/Homebrew/utils/sorbet.rb

@@ -0,0 +1,8 @@
+# typed: strict
+# frozen_string_literal: true
+
+if ENV["HOMEBREW_TESTS_COVERAGE"]
+  require "sorbet-runtime"
+else
+  require "utils/sorbet/stubs"
+end

Library/Homebrew/utils/sorbet/stubs.rb

@@ -0,0 +1,85 @@
+# typed: false
+# frozen_string_literal: true
+
+# Stubs for `sorbet-runtime`, all taken from `sorbet/t` except for `T::Sig.sig`.
+#
+# @private
+module T
+  # rubocop:disable Style/Documentation
+  module Sig
+    module WithoutRuntime
+      def self.sig(arg = nil, &blk); end
+    end
+
+    module_function
+
+    def sig(arg = nil, &blk); end
+  end
+
+  def self.any(type_a, type_b, *types); end
+
+  def self.nilable(type); end
+
+  def self.untyped; end
+
+  def self.noreturn; end
+
+  def self.all(type_a, type_b, *types); end
+
+  def self.enum(values); end
+
+  def self.proc; end
+
+  def self.self_type; end
+
+  def self.class_of(klass); end
+
+  def self.type_alias(type = nil, &blk); end
+
+  def self.type_parameter(name); end
+
+  def self.cast(value, _type, checked: true)
+    value
+  end
+
+  def self.let(value, _type, checked: true)
+    value
+  end
+
+  def self.assert_type!(value, _type, checked: true)
+    value
+  end
+
+  def self.unsafe(value)
+    value
+  end
+
+  def self.must(arg, _msg = nil)
+    arg
+  end
+
+  def self.reveal_type(value)
+    value
+  end
+
+  module Array
+    def self.[](type); end
+  end
+
+  module Hash
+    def self.[](keys, values); end
+  end
+
+  module Enumerable
+    def self.[](type); end
+  end
+
+  module Range
+    def self.[](type); end
+  end
+
+  module Set
+    def self.[](type); end
+  end
+  # rubocop:enable Style/Documentation
+end