Fix tests for for versions of ruby before ::Data

1. `defined?(::Data)` is insufficient: there was an earlier `::Data`
   class before the new one was added.  Checking for `Data.define`.
2. arg forwarding with `def foo(...)` wasn't introduced until 2.7.3.
3. implicit hash/kwparam values wasn't added until 3.1.

Author: nevans

test/psych/test_data.rb

@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 require_relative 'helper'
 
-return unless defined?(::Data)
+return unless defined?(::Data.define)
 
 class PsychDataWithIvar < Data.define(:foo)
   attr_reader :bar
-  def initialize(...)
+  def initialize(**)
     @bar = 'hello'
     super
   end

test/psych/test_object_references.rb

@@ -31,8 +31,10 @@ def test_struct_has_references
       assert_reference_trip Struct.new(:foo).new(1)
     end
 
-    def test_data_has_references
-      assert_reference_trip Data.define(:foo).new(1)
+    if defined?(::Data.define)
+      def test_data_has_references
+        assert_reference_trip Data.define(:foo).new(1)
+      end
     end
 
     def assert_reference_trip obj

test/psych/test_safe_load.rb

@@ -114,32 +114,34 @@ def test_anon_struct
       end
     end
 
-    D = Data.define(:d)
-    def test_data_depends_on_sym
-      assert_safe_cycle(D.new(nil), permitted_classes: [D, Symbol])
-      assert_raise(Psych::DisallowedClass) do
-        cycle D.new(nil), permitted_classes: [D]
+    if defined?(::Data.define)
+      D = Data.define(:d)
+      def test_data_depends_on_sym
+        assert_safe_cycle(D.new(nil), permitted_classes: [D, Symbol])
+        assert_raise(Psych::DisallowedClass) do
+          cycle D.new(nil), permitted_classes: [D]
+        end
       end
-    end
 
-    def test_anon_data
-      assert Psych.safe_load(<<-eoyml, permitted_classes: [Data, Symbol])
+      def test_anon_data
+        assert Psych.safe_load(<<-eoyml, permitted_classes: [Data, Symbol])
 --- !ruby/data
   foo: bar
-                      eoyml
+        eoyml
 
-      assert_raise(Psych::DisallowedClass) do
-        Psych.safe_load(<<-eoyml, permitted_classes: [Data])
+        assert_raise(Psych::DisallowedClass) do
+          Psych.safe_load(<<-eoyml, permitted_classes: [Data])
 --- !ruby/data
   foo: bar
-                      eoyml
-      end
+          eoyml
+        end
 
-      assert_raise(Psych::DisallowedClass) do
-        Psych.safe_load(<<-eoyml, permitted_classes: [Symbol])
+        assert_raise(Psych::DisallowedClass) do
+          Psych.safe_load(<<-eoyml, permitted_classes: [Symbol])
 --- !ruby/data
   foo: bar
-                      eoyml
+          eoyml
+        end
       end
     end
 

test/psych/test_serialize_subclasses.rb

@@ -36,20 +36,23 @@ def test_struct_subclass
       assert_equal so, Psych.unsafe_load(Psych.dump(so))
     end
 
-    class DataSubclass < Data.define(:foo)
-      def initialize(foo:)
-        @bar = "hello #{foo}"
-        super(foo:)
+    if defined?(::Data.define)
+      class DataSubclass < Data.define(:foo)
+        def initialize(foo:)
+          @bar = "hello #{foo}"
+          super(foo: foo)
+        end
+
+        def == other
+          super(other) && @bar == other.instance_eval{ @bar }
+        end
       end
 
-      def == other
-        super(other) && @bar == other.instance_eval{ @bar }
+      def test_data_subclass
+        so = DataSubclass.new('foo')
+        assert_equal so, Psych.unsafe_load(Psych.dump(so))
       end
     end
 
-    def test_data_subclass
-      so = DataSubclass.new('foo')
-      assert_equal so, Psych.unsafe_load(Psych.dump(so))
-    end
   end
 end

test/psych/test_yaml.rb

@@ -7,7 +7,7 @@
 # [ruby-core:01946]
 module Psych_Tests
     StructTest = Struct::new( :c )
-    DataTest   = Data.define( :c )
+    DataTest   = Data.define( :c ) if defined?(::Data.define)
 end
 
 class Psych_Unit_Tests < Psych::TestCase
@@ -1067,16 +1067,17 @@ def test_ruby_struct
 
     end
 
-    def test_ruby_data
-        Object.remove_const :MyBookData if Object.const_defined?(:MyBookData)
-        # Ruby Data value objects
-        book_class = Data.define(:author, :title, :year, :isbn)
-        Object.const_set(:MyBookData, book_class)
-        assert_to_yaml(
-            [ book_class.new( "Yukihiro Matsumoto", "Ruby in a Nutshell", 2002, "0-596-00214-9" ),
-              book_class.new( [ 'Dave Thomas', 'Andy Hunt' ], "The Pickaxe", 2002,
-                book_class.new( "This should be the ISBN", "but I have more data here", 2002, "None" )
-              ) ], <<EOY
+    if defined?(::Data.define)
+      def test_ruby_data
+          Object.remove_const :MyBookData if Object.const_defined?(:MyBookData)
+          # Ruby Data value objects
+          book_class = Data.define(:author, :title, :year, :isbn)
+          Object.const_set(:MyBookData, book_class)
+          assert_to_yaml(
+              [ book_class.new( "Yukihiro Matsumoto", "Ruby in a Nutshell", 2002, "0-596-00214-9" ),
+                book_class.new( [ 'Dave Thomas', 'Andy Hunt' ], "The Pickaxe", 2002,
+                  book_class.new( "This should be the ISBN", "but I have more data here", 2002, "None" )
+                ) ], <<EOY
 - !ruby/data:MyBookData
   author: Yukihiro Matsumoto
   title: Ruby in a Nutshell
@@ -1094,13 +1095,14 @@ def test_ruby_data
     year: 2002
     isbn: None
 EOY
-        )
+          )
 
-        assert_to_yaml( Psych_Tests::DataTest.new( 123 ), <<EOY )
+          assert_to_yaml( Psych_Tests::DataTest.new( 123 ), <<EOY )
 --- !ruby/data:Psych_Tests::DataTest
 c: 123
 EOY
 
+      end
     end
 
     def test_ruby_rational

test/psych/visitors/test_yaml_tree.rb

@@ -73,22 +73,24 @@ def test_override_method
         assert_equal s.method, obj.method
       end
 
-      D = Data.define(:foo)
+      if defined?(::Data.define)
+        D = Data.define(:foo)
 
-      def test_data
-        assert_cycle D.new('bar')
-      end
+        def test_data
+          assert_cycle D.new('bar')
+        end
 
-      def test_data_anon
-        d = Data.define(:foo).new('bar')
-        obj =  Psych.unsafe_load(Psych.dump(d))
-        assert_equal d.foo, obj.foo
-      end
+        def test_data_anon
+          d = Data.define(:foo).new('bar')
+          obj =  Psych.unsafe_load(Psych.dump(d))
+          assert_equal d.foo, obj.foo
+        end
 
-      def test_data_override_method
-        d = Data.define(:method).new('override')
-        obj =  Psych.unsafe_load(Psych.dump(d))
-        assert_equal d.method, obj.method
+        def test_data_override_method
+          d = Data.define(:method).new('override')
+          obj =  Psych.unsafe_load(Psych.dump(d))
+          assert_equal d.method, obj.method
+        end
       end
 
       def test_exception