1 files changed, 24 insertions, 0 deletions
diff --git a/spec/ruby/core/threadgroup/enclose_spec.rb b/spec/ruby/core/threadgroup/enclose_spec.rb
new file mode 100644
index 0000000000..6f703d4ce2
--- /dev/null
+++ b/spec/ruby/core/threadgroup/enclose_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+describe "ThreadGroup#enclose" do
+  before :each do
+    @q1, @q2 = Queue.new, Queue.new
+    @thread = Thread.new { @q1 << :go; @q2.pop }
+    @q1.pop
+  end
+
+  after :each do
+    @q2 << :done
+    @thread.join
+  end
+
+  it "raises a ThreadError if attempting to move a Thread from an enclosed ThreadGroup" do
+    thread_group = ThreadGroup.new
+    default_group = @thread.group
+    thread_group.add(@thread)
+    thread_group.enclose
+    -> do
+      default_group.add(@thread)
+    end.should.raise(ThreadError)
+  end
+end