WIP fix for Jruby spec

spec/rspec/support/spec/stderr_splitter_spec.rb

@@ -100,26 +100,24 @@
   end
 
   it 'is able to restore the stream from a cloned StdErrSplitter' do
-    if RSpec::Support::Ruby.jruby? && Tempfile.new("foo").is_a?(File) == false
-      skip """
-      This spec is currently unsupported on JRuby on CI due to tempfiles not being
-      a file, this situtation was discussed here https://github.com/rspec/rspec-support/pull/598#issuecomment-2200779633
-      """
-    end
-
     cloned = splitter.clone
-    expect(splitter.to_io).not_to be_a(File)
+    expect(splitter.to_io).to be_stderr
 
     tempfile = Tempfile.new("foo")
     begin
       splitter.reopen(tempfile)
-      expect(splitter.to_io).to be_a(File)
+      expect(splitter.to_io).to_not be_stderr
     ensure
       splitter.reopen(cloned)
       tempfile.close
       tempfile.unlink
     end
     # This is the important part of the test that would fail without proper cloning hygeine
-    expect(splitter.to_io).not_to be_a(File)
+    expect(splitter.to_io).to be_stderr
+  end
+
+  # Detecting STDERR in a way that doesn't use a reference
+  def be_stderr
+    have_attributes({:isatty => true, :path => "<STDERR>"})
   end
 end