1 files changed, 46 insertions, 0 deletions
diff --git a/test/ruby/test_frozen.rb b/test/ruby/test_frozen.rb
new file mode 100644
index 0000000000..6721cb1128
--- /dev/null
+++ b/test/ruby/test_frozen.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: false
+require 'test/unit'
+
+class TestFrozen < Test::Unit::TestCase
+  def test_setting_ivar_on_frozen_obj
+    obj = Object.new
+    obj.freeze
+    assert_raise(FrozenError) { obj.instance_variable_set(:@a, 1) }
+  end
+
+  def test_setting_ivar_on_frozen_obj_with_ivars
+    obj = Object.new
+    obj.instance_variable_set(:@a, 1)
+    obj.freeze
+    assert_raise(FrozenError) { obj.instance_variable_set(:@b, 1) }
+  end
+
+  def test_setting_ivar_on_frozen_string
+    str = "str"
+    str.freeze
+    assert_raise(FrozenError) { str.instance_variable_set(:@a, 1) }
+  end
+
+  def test_setting_ivar_on_frozen_string_with_ivars
+    str = "str"
+    str.instance_variable_set(:@a, 1)
+    str.freeze
+    assert_raise(FrozenError) { str.instance_variable_set(:@b, 1) }
+  end
+
+  def test_setting_ivar_on_frozen_string_with_singleton_class
+    str = "str"
+    str.singleton_class
+    str.freeze
+    assert_raise_with_message(FrozenError, "can't modify frozen String: \"str\"") { str.instance_variable_set(:@a, 1) }
+  end
+
+  class A
+    freeze
+  end
+
+  def test_setting_ivar_on_frozen_class
+    assert_raise_with_message(FrozenError, "can't modify frozen Class: TestFrozen::A") { A.instance_variable_set(:@a, 1) }
+    assert_raise_with_message(FrozenError, "can't modify frozen Class: #<Class:TestFrozen::A>") { A.singleton_class.instance_variable_set(:@a, 1) }
+  end
+end