improve test to check errors roundtrip

Author: davidhewitt

src/errors/validation_exception.rs

@@ -347,7 +347,7 @@ impl ValidationError {
         let callable = slf.getattr("from_exception_data")?;
         let borrow = slf.try_borrow()?;
         let args = (
-            borrow.title.as_ref(slf.py()),
+            borrow.title.as_ref(py),
             borrow.errors(py, include_url_env(py), true, true)?,
             borrow.input_type.into_py(py),
             borrow.hide_input,

tests/test_errors.py

@@ -1077,9 +1077,14 @@ def test_hide_input_in_json() -> None:
         assert 'input' not in error
 
 
+@pytest.mark.skipif(
+    sys.version_info < (3, 9) and sys.implementation == 'pypy', reason='PyPy before 3.9 cannot pickle this correctly'
+)
 def test_validation_error_pickle() -> None:
     s = SchemaValidator({'type': 'int'})
     with pytest.raises(ValidationError) as exc_info:
         s.validate_python('definitely not an int')
 
-    pickle.loads(pickle.dumps(exc_info.value))
+    original = exc_info.value
+    roundtripped = pickle.loads(pickle.dumps(original))
+    assert original.errors() == roundtripped.errors()