Add existing RBS interface tests from ruby/rbs repo

Author: sferik

.github/workflows/sig.yml

@@ -0,0 +1,18 @@
+name: sig
+
+on: [push, pull_request]
+
+jobs:
+  sig:
+    runs-on: ubuntu-latest
+    env:
+      BUNDLE_WITH: sig
+    steps:
+    - uses: actions/checkout@v6
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ruby
+        bundler-cache: true
+    - name: Run RBS test
+      run: bundle exec rake rbs:test

Gemfile

@@ -5,3 +5,8 @@ gemspec
 gem "rake"
 gem "test-unit"
 gem "test-unit-ruby-core"
+
+group :sig do
+  gem "rbs"
+  gem "rdoc"
+end

Rakefile

@@ -7,4 +7,12 @@ Rake::TestTask.new(:test) do |t|
   t.test_files = FileList["test/**/test_*.rb"]
 end
 
+namespace :rbs do
+  Rake::TestTask.new(:test) do |t|
+    t.libs << "test_sig"
+    t.ruby_opts << "-rtest_helper"
+    t.test_files = FileList["test_sig/test_*.rb"]
+  end
+end
+
 task :default => :test

test_sig/test_helper.rb

@@ -0,0 +1,48 @@
+require "pathname"
+require "test/unit"
+require "rbs"
+require "rbs/test"
+require "rbs/unit_test"
+
+module NetHTTPTestSigHelper
+  extend self
+
+  LOCAL_SIG_DIR = Pathname(__dir__).join("..", "sig").expand_path
+  SUPPORT_LIBRARIES = %w[
+    cgi
+    net-protocol
+    open-uri
+    openssl
+    resolv
+    securerandom
+    socket
+    strscan
+    tempfile
+    timeout
+    uri
+    zlib
+  ].freeze
+
+  def env
+    @env ||= begin
+      loader = RBS::EnvironmentLoader.new
+      loader.add(path: LOCAL_SIG_DIR)
+      SUPPORT_LIBRARIES.each do |library|
+        loader.add(library: library, version: nil)
+      end
+      RBS::Environment.from_loader(loader).resolve_type_names
+    end
+  end
+end
+
+class NetHTTPRBSTestCase < Test::Unit::TestCase
+  include RBS::UnitTest::TypeAssertions
+
+  def self.env
+    NetHTTPTestSigHelper.env
+  end
+
+  def self.builder
+    @builder ||= RBS::DefinitionBuilder.new(env: env)
+  end
+end