Handle error from Enum's missing function as ValidationError (#1274)

Author: sydney-runkle

src/validators/enum_.rs

@@ -121,7 +121,15 @@ impl<T: EnumValidateValue> Validator for EnumValidator<T> {
             return Ok(v);
         } else if let Some(ref missing) = self.missing {
             state.floor_exactness(Exactness::Lax);
-            let enum_value = missing.bind(py).call1((input.to_object(py),))?;
+            let enum_value = missing.bind(py).call1((input.to_object(py),)).map_err(|_| {
+                ValError::new(
+                    ErrorType::Enum {
+                        expected: self.expected_repr.clone(),
+                        context: None,
+                    },
+                    input,
+                )
+            })?;
             // check enum_value is an instance of the class like
             // https://github.com/python/cpython/blob/v3.12.2/Lib/enum.py#L1148
             if enum_value.is_instance(class)? {

tests/validators/test_enums.py

@@ -1,6 +1,6 @@
 import re
 import sys
-from enum import Enum
+from enum import Enum, IntFlag
 
 import pytest
 
@@ -267,3 +267,21 @@ class MyEnum(Enum):
 
     with pytest.raises(SchemaError, match='`members` should have length > 0'):
         SchemaValidator(core_schema.enum_schema(MyEnum, []))
+
+
+def test_missing_error_converted_to_val_error() -> None:
+    class MyFlags(IntFlag):
+        OFF = 0
+        ON = 1
+
+    v = SchemaValidator(
+        core_schema.with_default_schema(
+            schema=core_schema.enum_schema(MyFlags, list(MyFlags.__members__.values())), default=MyFlags.OFF
+        )
+    )
+
+    assert v.validate_python(MyFlags.OFF) is MyFlags.OFF
+    assert v.validate_python(0) is MyFlags.OFF
+
+    with pytest.raises(ValidationError):
+        v.validate_python(None)