Output state errors more clearly

Errors from blockchain fixtures were being swallowed silently. Output
these along with a full stack trace to make debugging easier.

Author: lrettig

tests/json-fixtures/test_state.py

@@ -2,6 +2,8 @@
 
 import pytest
 
+import traceback
+
 from eth_keys import keys
 
 from evm.db import (
@@ -43,13 +45,18 @@
     should_run_slow_tests,
 )
 
+from tests.conftest import vm_logger
+
 
 ROOT_PROJECT_DIR = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
 
 
 BASE_FIXTURE_PATH = os.path.join(ROOT_PROJECT_DIR, 'fixtures', 'GeneralStateTests')
 
 
+LOGGER = vm_logger()
+
+
 @to_tuple
 def expand_fixtures_forks(all_fixtures):
     """
@@ -295,6 +302,8 @@ def test_state_fixtures(fixture, fixture_vm_class):
         computation, _ = vm.apply_transaction(transaction)
     except ValidationError as err:
         transaction_error = err
+        LOGGER.warn("Got transaction error:")
+        LOGGER.warn(traceback.format_exc())
     else:
         transaction_error = False