1 files changed, 29 insertions, 1 deletions
diff --git a/spec/ruby/core/objectspace/undefine_finalizer_spec.rb b/spec/ruby/core/objectspace/undefine_finalizer_spec.rb
index 11d43121f8..98ffc6a986 100644
--- a/spec/ruby/core/objectspace/undefine_finalizer_spec.rb
+++ b/spec/ruby/core/objectspace/undefine_finalizer_spec.rb
@@ -1,5 +1,33 @@
 require_relative '../../spec_helper'
 
 describe "ObjectSpace.undefine_finalizer" do
-  it "needs to be reviewed for spec completeness"
+  it "removes finalizers for an object" do
+    code = <<~RUBY
+      obj = Object.new
+      ObjectSpace.define_finalizer(obj, proc { |id| puts "hello" })
+      ObjectSpace.undefine_finalizer(obj)
+    RUBY
+
+    ruby_exe(code).should.empty?
+  end
+
+  it "should not remove finalizers for a frozen object" do
+    code = <<~RUBY
+      obj = Object.new
+      ObjectSpace.define_finalizer(obj, proc { |id| print "ok" })
+      obj.freeze
+      begin
+        ObjectSpace.undefine_finalizer(obj)
+      rescue
+      end
+    RUBY
+
+    ruby_exe(code).should == "ok"
+  end
+
+  it "should raise when removing finalizers for a frozen object" do
+    obj = Object.new
+    obj.freeze
+    -> { ObjectSpace.undefine_finalizer(obj) }.should.raise(FrozenError)
+  end
 end