spec/ruby/core/module/attr_*: Add version guards

spec/ruby/core/module/attr_accessor_spec.rb

@@ -67,11 +67,21 @@ describe "Module#attr_accessor" do
     Module.should have_public_instance_method(:attr_accessor, false)
   end
 
+  ruby_version_is ""..."3.0" do
+    it "returns nil" do
+      Class.new do
+        (attr_accessor :foo, 'bar').should == nil
+      end
+    end
+  end
+
+  ruby_version_is "3.0" do
     it "returns an array of defined methods names as symbols" do
       Class.new do
         (attr_accessor :foo, 'bar').should == [:foo, :foo=, :bar, :bar=]
       end
     end
+  end
 
   describe "on immediates" do
     before :each do

spec/ruby/core/module/attr_reader_spec.rb

@@ -62,9 +62,19 @@ describe "Module#attr_reader" do
     Module.should have_public_instance_method(:attr_reader, false)
   end
 
+  ruby_version_is ""..."3.0" do
+    it "returns nil" do
+      Class.new do
+        (attr_reader :foo, 'bar').should == nil
+      end
+    end
+  end
+
+  ruby_version_is "3.0" do
     it "returns an array of defined methods names as symbols" do
       Class.new do
         (attr_reader :foo, 'bar').should == [:foo, :bar]
       end
     end
+  end
 end

spec/ruby/core/module/attr_spec.rb

@@ -146,6 +146,17 @@ describe "Module#attr" do
     Module.should have_public_instance_method(:attr, false)
   end
 
+  ruby_version_is ""..."3.0" do
+    it "returns nil" do
+      Class.new do
+        (attr :foo, 'bar').should == nil
+        (attr :baz, false).should == nil
+        (attr :qux, true).should == nil
+      end
+    end
+  end
+
+  ruby_version_is "3.0" do
     it "returns an array of defined methods names as symbols" do
       Class.new do
         (attr :foo, 'bar').should == [:foo, :bar]
@@ -153,4 +164,5 @@ describe "Module#attr" do
         (attr :qux, true).should == [:qux, :qux=]
       end
     end
+  end
 end

spec/ruby/core/module/attr_writer_spec.rb

@@ -62,9 +62,19 @@ describe "Module#attr_writer" do
     Module.should have_public_instance_method(:attr_writer, false)
   end
 
+  ruby_version_is ""..."3.0" do
+    it "returns nil" do
+      Class.new do
+        (attr_writer :foo, 'bar').should == nil
+      end
+    end
+  end
+
+  ruby_version_is "3.0" do
     it "returns an array of defined methods names as symbols" do
       Class.new do
         (attr_writer :foo, 'bar').should == [:foo=, :bar=]
       end
     end
+  end
 end