1 files changed, 6 insertions, 0 deletions
diff --git a/test/ruby/test_lambda.rb b/test/ruby/test_lambda.rb
index 826bfcf203..3ac2e4cb98 100644
--- a/test/ruby/test_lambda.rb
+++ b/test/ruby/test_lambda.rb
@@ -101,6 +101,12 @@ class TestLambdaParameters < Test::Unit::TestCase
     assert_equal(:ok, x, bug13090)
   end
 
+  def test_arity_error
+    assert_raise(ArgumentError, '[Bug #12705]') do
+      [1, 2].tap(&lambda {|a, b|})
+    end
+  end
+
   def foo
     assert_equal(nil, ->(&b){ b }.call)
   end