WIP fix for Jruby spec

spec/rspec/support/spec/stderr_splitter_spec.rb

@@ -101,26 +101,24 @@
 
   # This spec replicates what matchers do when capturing stderr, e.g `to_stderr_from_any_process`
   it 'is able to restore the stream from a cloned StdErrSplitter' do
-    if RSpec::Support::Ruby.jruby?
-      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({:inspect => "#<IO:<STDERR>>"})
   end
 end