Livecheck::Options: Rework as T::Struct

As suggested, this reworks `Options` to subclass `T::Struct`, which
simplifies the implementation and makes it easier to maintain.

One noteworthy difference in switching to `T::Struct` is that
`#serialize` omits `nil` values but I don't _think_ this should be a
problem for us. In terms of changes, I modified `#merge` to remove a
now-unnecessary `compact` call and updated related tests.

Co-authored-by: Douglas Eichelberger <697964+dduugg@users.noreply.github.com>

Library/Homebrew/livecheck.rb

@@ -179,13 +179,9 @@ class Livecheck
   def url(url = T.unsafe(nil), homebrew_curl: nil, post_form: nil, post_json: nil)
     raise ArgumentError, "Only use `post_form` or `post_json`, not both" if post_form && post_json
 
-    if homebrew_curl || post_form || post_json
-      @options = @options.merge({
-        homebrew_curl:,
-        post_form:,
-        post_json:,
-      }.compact)
-    end
+    @options.homebrew_curl = homebrew_curl unless homebrew_curl.nil?
+    @options.post_form = post_form unless post_form.nil?
+    @options.post_json = post_json unless post_json.nil?
 
     case url
     when nil

Library/Homebrew/livecheck/options.rb

@@ -8,34 +8,15 @@ module Homebrew
     #
     # Option values use a `nil` default to indicate that the value has not been
     # set.
-    class Options
+    class Options < T::Struct
       # Whether to use brewed curl.
-      sig { returns(T.nilable(T::Boolean)) }
-      attr_reader :homebrew_curl
+      prop :homebrew_curl, T.nilable(T::Boolean)
 
       # Form data to use when making a `POST` request.
-      sig { returns(T.nilable(T::Hash[Symbol, String])) }
-      attr_reader :post_form
+      prop :post_form, T.nilable(T::Hash[Symbol, String])
 
       # JSON data to use when making a `POST` request.
-      sig { returns(T.nilable(T::Hash[Symbol, String])) }
-      attr_reader :post_json
-
-      # @param homebrew_curl whether to use brewed curl
-      # @param post_form form data to use when making a `POST` request
-      # @param post_json JSON data to use when making a `POST` request
-      sig {
-        params(
-          homebrew_curl: T.nilable(T::Boolean),
-          post_form:     T.nilable(T::Hash[Symbol, String]),
-          post_json:     T.nilable(T::Hash[Symbol, String]),
-        ).void
-      }
-      def initialize(homebrew_curl: nil, post_form: nil, post_json: nil)
-        @homebrew_curl = homebrew_curl
-        @post_form = post_form
-        @post_json = post_json
-      end
+      prop :post_json, T.nilable(T::Hash[Symbol, String])
 
       # Returns a `Hash` of options that are provided as arguments to `url`.
       sig { returns(T::Hash[Symbol, T.untyped]) }
@@ -47,25 +28,13 @@ module Homebrew
         }
       end
 
-      # Returns a `Hash` of all instance variables, using `Symbol` keys.
-      sig { returns(T::Hash[Symbol, T.untyped]) }
-      def to_h
-        {
-          homebrew_curl:,
-          post_form:,
-          post_json:,
-        }
-      end
-
       # Returns a `Hash` of all instance variables, using `String` keys.
       sig { returns(T::Hash[String, T.untyped]) }
-      def to_hash
-        {
-          "homebrew_curl" => @homebrew_curl,
-          "post_form"     => @post_form,
-          "post_json"     => @post_json,
-        }
-      end
+      def to_hash = serialize
+
+      # Returns a `Hash` of all instance variables, using `Symbol` keys.
+      sig { returns(T::Hash[Symbol, T.untyped]) }
+      def to_h = serialize.transform_keys(&:to_sym)
 
       # Returns a new object formed by merging `other` values with a copy of
       # `self`.
@@ -78,7 +47,7 @@ module Homebrew
         return dup if other.empty?
 
         this_hash = to_h
-        other_hash = other.is_a?(Options) ? other.to_h.compact : other
+        other_hash = other.is_a?(Options) ? other.to_h : other
         return dup if this_hash == other_hash
 
         new_options = this_hash.merge(other_hash)
@@ -96,15 +65,11 @@ module Homebrew
 
       # Whether the object has only default values.
       sig { returns(T::Boolean) }
-      def empty?
-        @homebrew_curl.nil? && @post_form.nil? && @post_json.nil?
-      end
+      def empty? = serialize.empty?
 
       # Whether the object has any non-default values.
       sig { returns(T::Boolean) }
-      def present?
-        !@homebrew_curl.nil? || !@post_form.nil? || !@post_json.nil?
-      end
+      def present? = !empty?
     end
   end
 end

Library/Homebrew/test/livecheck/options_spec.rb

@@ -39,21 +39,19 @@ RSpec.describe Homebrew::Livecheck::Options do
 
   describe "#to_h" do
     it "returns a Hash of all instance variables" do
-      expect(options.new.to_h).to eq({
-        homebrew_curl: nil,
-        post_form:     nil,
-        post_json:     nil,
-      })
+      # `T::Struct.serialize` omits `nil` values
+      expect(options.new.to_h).to eq({})
+
+      expect(options.new(**args).to_h).to eq(args)
     end
   end
 
   describe "#to_hash" do
     it "returns a Hash of all instance variables, using String keys" do
-      expect(options.new.to_hash).to eq({
-        "homebrew_curl" => nil,
-        "post_form"     => nil,
-        "post_json"     => nil,
-      })
+      # `T::Struct.serialize` omits `nil` values
+      expect(options.new.to_hash).to eq({})
+
+      expect(options.new(**args).to_hash).to eq(args.transform_keys(&:to_s))
     end
   end
 
@@ -65,6 +63,8 @@ RSpec.describe Homebrew::Livecheck::Options do
         .to eq(options.new(**merged_hash))
       expect(options.new(**args).merge(args))
         .to eq(options.new(**args))
+      expect(options.new(**args).merge({}))
+        .to eq(options.new(**args))
     end
   end
 
@@ -82,6 +82,10 @@ RSpec.describe Homebrew::Livecheck::Options do
     it "returns false if any instance variables differ" do
       expect(options.new == options.new(**args)).to be false
     end
+
+    it "returns false if other object is not the same class" do
+      expect(options.new == :other).to be false
+    end
   end
 
   describe "#empty?" do