livecheck/strategy: add ElectronBuilder strategy

Library/Homebrew/livecheck/strategy.rb

@@ -147,6 +147,7 @@ end
 require_relative "strategy/apache"
 require_relative "strategy/bitbucket"
 require_relative "strategy/cpan"
+require_relative "strategy/electron_builder"
 require_relative "strategy/git"
 require_relative "strategy/github_latest"
 require_relative "strategy/gnome"

Library/Homebrew/livecheck/strategy/electron_builder.rb

@@ -0,0 +1,75 @@
+# typed: false
+# frozen_string_literal: true
+
+module Homebrew
+  module Livecheck
+    module Strategy
+      # The {ElectronBuilder} strategy fetches content at a URL and parses
+      # it as an electron-builder appcast in YAML format.
+      #
+      # @api private
+      class ElectronBuilder
+        extend T::Sig
+
+        NICE_NAME = "electron-builder"
+
+        # A priority of zero causes livecheck to skip the strategy. We do this
+        # for {ElectronBuilder} so we can selectively apply the strategy using
+        # `strategy :electron_builder` in a `livecheck` block.
+        PRIORITY = 0
+
+        # The `Regexp` used to determine if the strategy applies to the URL.
+        URL_MATCH_REGEX = %r{^https?://.+?/.+?\.yml}i.freeze
+
+        # Whether the strategy can be applied to the provided URL.
+        #
+        # @param url [String] the URL to match against
+        # @return [Boolean]
+        sig { params(url: String).returns(T::Boolean) }
+        def self.match?(url)
+          URL_MATCH_REGEX.match?(url)
+        end
+
+        # Extract version information from page content.
+        #
+        # @param content [String] the content to check
+        # @return [String]
+        sig { params(content: String).returns(T.nilable(String)) }
+        def self.version_from_content(content)
+          require "yaml"
+
+          return unless (item = YAML.safe_load(content))
+
+          item["version"]
+        end
+
+        # Checks the content at the URL for new versions.
+        #
+        # @param url [String] the URL of the content to check
+        # @param regex [Regexp] a regex used for matching versions in content
+        # @return [Hash]
+        sig { params(url: String, regex: T.nilable(Regexp)).returns(T::Hash[Symbol, T.untyped]) }
+        def self.find_versions(url, regex = nil, &block)
+          raise ArgumentError, "The #{T.must(name).demodulize} strategy does not support a regex." if regex
+
+          match_data = { matches: {}, regex: regex, url: url }
+
+          match_data.merge!(Strategy.page_content(url))
+          content = match_data.delete(:content)
+
+          if (item = version_from_content(content))
+            match = if block
+              block.call(item)&.to_s
+            else
+              item
+            end
+
+            match_data[:matches][match] = Version.new(match) if match
+          end
+
+          match_data
+        end
+      end
+    end
+  end
+end

Library/Homebrew/test/livecheck/strategy/electron_builder_spec.rb

@@ -0,0 +1,50 @@
+# typed: false
+# frozen_string_literal: true
+
+require "livecheck/strategy/electron_builder"
+
+describe Homebrew::Livecheck::Strategy::ElectronBuilder do
+  subject(:electron_builder) { described_class }
+
+  let(:valid_url) { "https://www.example.com/example/latest-mac.yml" }
+  let(:invalid_url) { "https://www.example.com/example/example" }
+
+  let(:electron_builder_yaml) {
+    <<~EOS
+      version: 1.2.3
+      files:
+        - url: Example-1.2.3-mac.zip
+          sha512: MDXR0pxozBJjxxbtUQJOnhiaiiQkryLAwtcVjlnNiz30asm/PtSxlxWKFYN3kV/kl+jriInJrGypuzajTF6XIA==
+          size: 92031237
+          blockMapSize: 96080
+        - url: Example-1.2.3.dmg
+          sha512: k6WRDlZEfZGZHoOfUShpHxXZb5p44DRp+FAO2FXNx2kStZvyW9VuaoB7phPMfZpcMKrzfRfncpP8VEM8OB2y9g==
+          size: 94972630
+      path: Example-1.2.3-mac.zip
+      sha512: MDXR0pxozBJjxxbtUQJOnhiaiiQkryLAwtcVjlnNiz30asm/PtSxlxWKFYN3kV/kl+jriInJrGypuzajTF6XIA==
+      releaseDate: '2000-01-01T00:00:00.000Z'
+    EOS
+  }
+
+  describe "::match?" do
+    it "returns true for any URL pointing to a YAML file" do
+      expect(electron_builder.match?(valid_url)).to be true
+    end
+
+    it "returns false for a URL not pointing to a YAML file" do
+      expect(electron_builder.match?(invalid_url)).to be false
+    end
+  end
+
+  describe "::version_from_content" do
+    let(:version_from_electron_builder_yaml) { electron_builder.version_from_content(electron_builder_yaml) }
+
+    it "returns nil if content is blank" do
+      expect(electron_builder.version_from_content("")).to be nil
+    end
+
+    it "returns a version string when given YAML data" do
+      expect(version_from_electron_builder_yaml).to be_a(String)
+    end
+  end
+end