Followed up behavior change of set

  f360ebb

spec/ruby/library/set/pretty_print_spec.rb

@@ -1,17 +1,19 @@
 require_relative '../../spec_helper'
 require 'set'
 
-describe "Set#pretty_print" do
-  it "passes the 'pretty print' representation of self to the pretty print writer" do
-    pp = mock("PrettyPrint")
-    set = Set[1, 2, 3]
+ruby_version_is ""..."3.1" do
+  describe "Set#pretty_print" do
+    it "passes the 'pretty print' representation of self to the pretty print writer" do
+      pp = mock("PrettyPrint")
+      set = Set[1, 2, 3]
 
-    pp.should_receive(:text).with("#<Set: {")
-    pp.should_receive(:text).with("}>")
+      pp.should_receive(:text).with("#<Set: {")
+      pp.should_receive(:text).with("}>")
 
-    pp.should_receive(:nest).with(1).and_yield
-    pp.should_receive(:seplist).with(set)
+      pp.should_receive(:nest).with(1).and_yield
+      pp.should_receive(:seplist).with(set)
 
-    set.pretty_print(pp)
+      set.pretty_print(pp)
+    end
   end
 end