diff --git a/Lib/test/test_optimizer.py b/Lib/test/test_optimizer.py
new file mode 100644
index 000000000..fac4d1a4a
--- /dev/null
+++ b/Lib/test/test_optimizer.py
@@ -0,0 +1,90 @@
+import unittest
+import types
+from test.support import import_helper
+
+
+_testinternalcapi = import_helper.import_module("_testinternalcapi")
+
+
+class TestRareEventCounters(unittest.TestCase):
+    def setUp(self):
+        _testinternalcapi.reset_rare_event_counters()
+
+    def test_set_class(self):
+        class A:
+            pass
+        class B:
+            pass
+        a = A()
+
+        orig_counter = _testinternalcapi.get_rare_event_counters()["set_class"]
+        a.__class__ = B
+        self.assertEqual(
+            orig_counter + 1,
+            _testinternalcapi.get_rare_event_counters()["set_class"]
+        )
+
+    def test_set_bases(self):
+        class A:
+            pass
+        class B:
+            pass
+        class C(B):
+            pass
+
+        orig_counter = _testinternalcapi.get_rare_event_counters()["set_bases"]
+        C.__bases__ = (A,)
+        self.assertEqual(
+            orig_counter + 1,
+            _testinternalcapi.get_rare_event_counters()["set_bases"]
+        )
+
+    def test_set_eval_frame_func(self):
+        orig_counter = _testinternalcapi.get_rare_event_counters()["set_eval_frame_func"]
+        _testinternalcapi.set_eval_frame_record([])
+        self.assertEqual(
+            orig_counter + 1,
+            _testinternalcapi.get_rare_event_counters()["set_eval_frame_func"]
+        )
+        _testinternalcapi.set_eval_frame_default()
+
+    def test_builtin_dict(self):
+        orig_counter = _testinternalcapi.get_rare_event_counters()["builtin_dict"]
+        if isinstance(__builtins__, types.ModuleType):
+            builtins = __builtins__.__dict__
+        else:
+            builtins = __builtins__
+        builtins["FOO"] = 42
+        self.assertEqual(
+            orig_counter + 1,
+            _testinternalcapi.get_rare_event_counters()["builtin_dict"]
+        )
+        del builtins["FOO"]
+
+    def test_func_modification(self):
+        def func(x=0):
+            pass
+
+        for attribute in (
+            "__code__",
+            "__defaults__",
+            "__kwdefaults__"
+        ):
+            orig_counter = _testinternalcapi.get_rare_event_counters()["func_modification"]
+            setattr(func, attribute, getattr(func, attribute))
+            self.assertEqual(
+                orig_counter + 1,
+                _testinternalcapi.get_rare_event_counters()["func_modification"]
+            )
+
+
+class TestOptimizerSymbols(unittest.TestCase):
+
+    @unittest.skipUnless(hasattr(_testinternalcapi, "uop_symbols_test"),
+                "requires _testinternalcapi.uop_symbols_test")
+    def test_optimizer_symbols(self):
+        _testinternalcapi.uop_symbols_test()
+
+
+if __name__ == "__main__":
+    unittest.main()