Fix Ractor compatibility regression, add tests

lib/erb.rb

@@ -815,9 +815,6 @@
 # [template processor]: https://en.wikipedia.org/wiki/Template_processor
 #
 class ERB
-  IDENTITY_METHOD = BasicObject.instance_method(:equal?) # :nodoc:
-  private_constant :IDENTITY_METHOD
-
   # :markup: markdown
   #
   # :call-seq:
@@ -1117,7 +1114,7 @@ def new_toplevel(vars = nil)
   private :new_toplevel
 
   def initialized_by_new? # :nodoc:
-    IDENTITY_METHOD.bind_call(@_init, self.class.singleton_class)
+    self.class.singleton_class.equal? @_init
   end
   private :initialized_by_new?
 

lib/erb/compiler.rb

@@ -80,16 +80,11 @@ def initialize(str)
   end
 
   class Scanner # :nodoc:
-    @scanner_map = defined?(Ractor) ? Ractor.make_shareable({}) : {}
+    @scanner_map = {}.freeze
+
     class << self
-      if defined?(Ractor)
-        def register_scanner(klass, trim_mode, percent)
-          @scanner_map = Ractor.make_shareable({ **@scanner_map, [trim_mode, percent] => klass })
-        end
-      else
-        def register_scanner(klass, trim_mode, percent)
-          @scanner_map[[trim_mode, percent]] = klass
-        end
+      def register_scanner(klass, trim_mode, percent)
+        @scanner_map = @scanner_map.merge([trim_mode, percent].freeze => klass).freeze
       end
       alias :regist_scanner :register_scanner
     end

test/erb/test_erb.rb

@@ -740,3 +740,43 @@ def teardown
     ERB::Compiler::Scanner.instance_variable_set('@scanner_map', @save_map)
   end
 end
+
+class TestERBRactor < Test::Unit::TestCase
+  def test_compile_and_result_in_ractor
+    assert_ractor(<<~RUBY, require: 'erb')
+      r = Ractor.new do
+        ERB.new("Hello, <%= 'world' %>!").result(binding)
+      end
+      assert_equal("Hello, world!", r.value)
+    RUBY
+  end
+
+  def test_trim_mode_in_ractor
+    assert_ractor(<<~RUBY, require: 'erb')
+      src = "<% [1, 2].each do |i| %>\\n<%= i %>\\n<% end %>\\n"
+      r = Ractor.new(src) { |s| ERB.new(s, trim_mode: '-').result(binding) }
+      assert_equal("\\n1\\n\\n2\\n\\n", r.value)
+
+      r = Ractor.new(src) { |s| ERB.new(s, trim_mode: '<>').result(binding) }
+      assert_equal("12", r.value)
+    RUBY
+  end
+
+  def test_frozen_erb_instance_reused_across_ractors
+    assert_ractor(<<~RUBY, require: 'erb')
+      erb = ERB.new("<%= 1 + 1 %>")
+      erb.freeze
+      rs = 2.times.map { Ractor.new(erb) { |e| e.result(binding) } }
+      assert_equal(["2", "2"], rs.map(&:value))
+    RUBY
+  end
+
+  def test_util_html_escape_in_ractor
+    assert_ractor(<<~RUBY, require: 'erb')
+      r = Ractor.new do
+        ERB::Util.html_escape("<script>")
+      end
+      assert_equal("&lt;script&gt;", r.value)
+    RUBY
+  end
+end