Add Sorbet type checking

.github/workflows/ci.yml

@@ -39,3 +39,17 @@ jobs:
         gem install bundler -v 2.4.22
         bundle install --jobs 4 --retry 3
         bundle exec rake test
+
+  typecheck:
+    runs-on: ubuntu-latest
+    env:
+      BUNDLE_GEMFILE: Gemfile
+    steps:
+    - uses: actions/checkout@v4
+    - name: Setup Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 3.3
+        bundler-cache: true
+    - name: Run typecheck
+      run: bundle exec rake typecheck

Gemfile

@@ -3,6 +3,11 @@
 source 'https://rubygems.org'
 gemspec
 
+group :development do
+  gem 'sorbet', require: false
+  gem 'tapioca', require: false
+end
+
 gem 'pry'
 gem 'pry-byebug'
 gem 'warning'

Rakefile

@@ -16,6 +16,11 @@ namespace :benchmark do
   end
 end
 
+desc "Run Sorbet typecheck"
+task :typecheck do
+  sh "bundle exec srb tc"
+end
+
 desc "Run benchmarks"
 task benchmark: "benchmark:planner"
 

bin/tapioca

@@ -0,0 +1,16 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application 'tapioca' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../Gemfile", __dir__)
+
+require "rubygems"
+require "bundler/setup"
+
+load Gem.bin_path("tapioca", "tapioca")

lib/graphql/stitching.rb

@@ -1,39 +1,42 @@
 # frozen_string_literal: true
+# typed: true
 
 require "graphql"
 
 module GraphQL
   module Stitching
-    # scope name of query operations.
-    QUERY_OP = "query"
-
-    # scope name of mutation operations.
-    MUTATION_OP = "mutation"
-
-    # scope name of subscription operations.
-    SUBSCRIPTION_OP = "subscription"
-
-    # introspection typename field.
-    TYPENAME = "__typename"
-
-    # @api private
-    EMPTY_OBJECT = {}.freeze
-
-    # @api private
-    EMPTY_ARRAY = [].freeze
+    QUERY_OP = "query".freeze #: String
+
+    MUTATION_OP = "mutation".freeze #: String
+
+    SUBSCRIPTION_OP = "subscription".freeze #: String
+
+    TYPENAME = "__typename".freeze #: String
+
+    EMPTY_OBJECT = {}.freeze #: Hash[untyped, untyped]
+
+    EMPTY_ARRAY = [].freeze #: Array[untyped]
 
     class StitchingError < StandardError; end
     class CompositionError < StitchingError; end
     class ValidationError < CompositionError; end
     class DocumentError < StandardError
+      #: (String element) -> void
       def initialize(element)
         super("Invalid #{element} encountered in document")
       end
     end
 
+    MIN_VISIBILITY_VERSION = "2.5.3".freeze #: String
+
     class << self
-      # Proc used to compute digests; uses SHA2 by default.
-      # @returns [Proc] proc used to compute digests.
+      # @rbs!
+      #   @digest: ^(String) -> String
+      #   @stitch_directive: String
+      #   @visibility_directive: String
+      #   @supports_visibility: bool
+
+      #: ?{ (String) -> String } -> ^(String) -> String
       def digest(&block)
         if block_given?
           @digest = block
@@ -42,25 +45,23 @@ def digest(&block)
         end
       end
 
-      # Name of the directive used to mark type resolvers.
-      # @returns [String] name of the type resolver directive.
+      #: -> String
       def stitch_directive
-        @stitch_directive ||= "stitch"
+        @stitch_directive ||= "stitch".freeze
       end
 
+      #: String
       attr_writer :stitch_directive
 
-      # Name of the directive used to denote member visibilities.
-      # @returns [String] name of the visibility directive.
+      #: -> String
       def visibility_directive
-        @visibility_directive ||= "visibility"
+        @visibility_directive ||= "visibility".freeze
       end
 
+      #: String
       attr_writer :visibility_directive
 
-      MIN_VISIBILITY_VERSION = "2.5.3"
-
-      # @returns Boolean true if GraphQL::Schema::Visibility is fully supported
+      #: -> bool
       def supports_visibility?
         return @supports_visibility if defined?(@supports_visibility)
 

lib/graphql/stitching/client.rb

@@ -1,25 +1,22 @@
 # frozen_string_literal: true
+# typed: true
 
 require "json"
 
 module GraphQL
   module Stitching
-    # Client is an out-of-the-box helper that assembles all 
-    # stitching components into a workflow that executes requests.
     class Client
       class << self
+        #: (String | singleton(GraphQL::Schema) schema, executables: Hash[Location | Symbol, Executable]) -> Client
         def from_definition(schema, executables:)
           new(supergraph: Supergraph.from_definition(schema, executables: executables))
         end
       end
 
-      # @return [Supergraph] composed supergraph that services incoming requests.
+      #: Supergraph
       attr_reader :supergraph
 
-      # Builds a new client instance. Either `supergraph` or `locations` configuration is required.
-      # @param supergraph [Supergraph] optional, a pre-composed supergraph that bypasses composer setup.
-      # @param locations [Hash<Symbol, Hash<Symbol, untyped>>] optional, composer configurations for each graph location.
-      # @param composer_options [Hash] optional, composer options for configuring composition.
+      #: (?locations: untyped, ?supergraph: Supergraph?, ?composer_options: Hash[Symbol, untyped]) -> void
       def initialize(locations: nil, supergraph: nil, composer_options: {})
         @supergraph = if locations && supergraph
           raise ArgumentError, "Cannot provide both locations and a supergraph."
@@ -34,15 +31,26 @@ def initialize(locations: nil, supergraph: nil, composer_options: {})
           composer.perform(locations)
         end
 
-        @on_cache_read = nil
-        @on_cache_write = nil
-        @on_error = nil
+        @on_cache_read = nil #: CacheReadHandler?
+        @on_cache_write = nil #: CacheWriteHandler?
+        @on_error = nil #: ErrorHandler?
       end
 
+      #: (
+      #|   ?String | DocumentNode | nil raw_query,
+      #|   ?query: String | DocumentNode | nil,
+      #|   ?variables: Variables?,
+      #|   ?operation_name: String?,
+      #|   ?context: untyped,
+      #|   ?validate: bool
+      #| ) -> untyped
       def execute(raw_query = nil, query: nil, variables: nil, operation_name: nil, context: nil, validate: true)
+        source = raw_query || query
+        raise ArgumentError, "A query string or document is required." unless source
+
         request = Request.new(
           @supergraph,
-          raw_query || query, # << for parity with GraphQL Ruby Schema.execute
+          source,
           operation_name: operation_name,
           variables: variables,
           context: context,
@@ -62,23 +70,27 @@ def execute(raw_query = nil, query: nil, variables: nil, operation_name: nil, co
         error_result(request, [{ "message" => custom_message || "An unexpected error occured." }])
       end
 
+      #: ?{ (Request) -> String? } -> CacheReadHandler
       def on_cache_read(&block)
-        raise ArgumentError, "A cache read block is required." unless block_given?
+        raise ArgumentError, "A cache read block is required." unless block
         @on_cache_read = block
       end
 
+      #: ?{ (Request, String) -> void } -> CacheWriteHandler
       def on_cache_write(&block)
-        raise ArgumentError, "A cache write block is required." unless block_given?
+        raise ArgumentError, "A cache write block is required." unless block
         @on_cache_write = block
       end
 
+      #: ?{ (Request?, StandardError) -> String? } -> ErrorHandler
       def on_error(&block)
-        raise ArgumentError, "An error handler block is required." unless block_given?
+        raise ArgumentError, "An error handler block is required." unless block
         @on_error = block
       end
 
       private
 
+      #: (Request request) -> Plan
       def load_plan(request)
         if @on_cache_read && plan_json = @on_cache_read.call(request)
           plan = Plan.from_json(JSON.parse(plan_json))
@@ -98,6 +110,7 @@ def load_plan(request)
         plan
       end
 
+      #: (Request? request, Array[PublicErrorObject | PublicError] errors) -> GraphQL::Query::Result
       def error_result(request, errors)
         public_errors = errors.map! do |e|
           e.is_a?(Hash) ? e : e.to_h