1 files changed, 50 insertions, 0 deletions
diff --git a/test/-ext-/thread/test_lock_native_thread.rb b/test/-ext-/thread/test_lock_native_thread.rb
new file mode 100644
index 0000000000..8a5ba78838
--- /dev/null
+++ b/test/-ext-/thread/test_lock_native_thread.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: false
+
+require 'envutil'
+
+mn_supported_p = -> do
+  out, *_ = EnvUtil.invoke_ruby([{'RUBY_MN_THREADS' => '1'}, '-v'], '', true)
+  return /\+MN/ =~ out
+end
+
+if mn_supported_p.call
+  # test only on MN threads
+else
+  return
+end
+
+class TestThreadLockNativeThread < Test::Unit::TestCase
+  def test_lock_native_thread
+    assert_separately([{'RUBY_MN_THREADS' => '1'}], <<-RUBY)
+      require '-test-/thread/lock_native_thread'
+
+      Thread.new{
+        assert_equal true, Thread.current.lock_native_thread
+      }.join
+
+      # main thread already has DNT
+      assert_equal false, Thread.current.lock_native_thread
+    RUBY
+  end
+
+  def test_lock_native_thread_tls
+    assert_separately([{'RUBY_MN_THREADS' => '1'}], <<-RUBY)
+      require '-test-/thread/lock_native_thread'
+      tn = 10
+      ln = 1_000
+
+      ts = tn.times.map{|i|
+        Thread.new(i){|i|
+          Thread.current.set_tls i
+          assert_equal true, Thread.current.lock_native_thread
+
+          ln.times{
+            assert_equal i, Thread.current.get_tls
+            Thread.pass
+          }
+        }
+      }
+      ts.each(&:join)
+    RUBY
+  end
+end