Use an isolated class

The number of all instances of `Class` may be affected by GC-able
anonymous classes created by other tests.

1 files changed, 4 insertions, 3 deletions

diff --git a/spec/ruby/library/objectspace/memsize_of_all_spec.rb b/spec/ruby/library/objectspace/memsize_of_all_spec.rb
index 6898862e8f..c5a48165ce 100644
--- a/spec/ruby/library/objectspace/memsize_of_all_spec.rb
+++ b/spec/ruby/library/objectspace/memsize_of_all_spec.rb
@@ -13,9 +13,10 @@ describe "ObjectSpace.memsize_of_all" do
   end
 
   it "increases when a new object is allocated" do
-    before = ObjectSpace.memsize_of_all(Class)
-    o = Class.new
-    after = ObjectSpace.memsize_of_all(Class)
+    c = Class.new
+    before = ObjectSpace.memsize_of_all(c)
+    o = c.new
+    after = ObjectSpace.memsize_of_all(c)
     after.should > before
   end
 end