Adding working (and not working) tests for issue

Author: henryiii

include/pybind11/pybind11.h

@@ -1362,7 +1362,7 @@ template <typename Type> class enum_ : public class_<Type> {
 
         constexpr bool is_arithmetic = detail::any_of<std::is_same<arithmetic, Extra>...>::value;
 
-        auto entries = m_entries;
+        dict& entries = m_entries;
         def("__repr__", [name, entries](Type value) -> pybind11::str {
             for (const auto &kv : entries) {
                 if (pybind11::cast<Type>(kv.second) == value)

tests/test_enum.py

@@ -46,7 +46,18 @@ def test_converstion_enum():
     assert m.test_conversion_enum(m.ConversionEnum.Convert1) == "ConversionEnum::Convert1"
     assert m.test_conversion_enum(m.ConversionEnum("Convert1")) == "ConversionEnum::Convert1"
     assert m.test_conversion_enum("Convert1") == "ConversionEnum::Convert1"
-    assert m.test_conversion_enum(m.ConversionEnum.Convert1) == "ConversionEnum::Convert1"
+
+
+def test_conversion_enum_raises():
+    with pytest.raises(ValueError) as excinfo:
+        m.ConversionEnum("Convert0")
+    assert str(excinfo.value) == "\"Convert0\" is not a valid value for enum type ConversionEnum"
+
+
+def test_conversion_enum_raises_implicit():
+    with pytest.raises(ValueError) as excinfo:
+        m.test_conversion_enum("Convert0")
+    assert str(excinfo.value) == "\"Convert0\" is not a valid value for enum type ConversionEnum"
 
 
 def test_scoped_enum():