Add Berlin tests, disabled in CI

It doesn't make sense to turn them on until most of the EIPs are
implemented.

Author: carver

.circleci/config.yml

@@ -46,6 +46,12 @@ jobs:
       - image: circleci/python:3.6
         environment:
           TOXENV: py36-benchmark
+  py36-native-blockchain-berlin:
+    <<: *common
+    docker:
+      - image: circleci/python:3.6
+        environment:
+          TOXENV: py36-native-blockchain-berlin
   py36-native-blockchain-byzantium:
     <<: *common
     docker:

eth/tools/fixtures/helpers.py

@@ -46,6 +46,7 @@
     HomesteadVM as BaseHomesteadVM,
     SpuriousDragonVM,
     IstanbulVM,
+    BerlinVM,
 )
 
 
@@ -126,6 +127,10 @@ def chain_vm_configuration(fixture: Dict[str, Any]) -> Iterable[Tuple[int, Type[
         return (
             (0, IstanbulVM),
         )
+    elif network == 'Berlin':
+        return (
+            (0, BerlinVM),
+        )
     elif network == 'FrontierToHomesteadAt5':
         HomesteadVM = BaseHomesteadVM.configure(support_dao_fork=False)
         return (

eth/vm/forks/__init__.py

@@ -25,3 +25,6 @@
 from .muir_glacier import (  # noqa: F401
     MuirGlacierVM,
 )
+from .berlin import (  # noqa: F401
+    BerlinVM,
+)

tox.ini

@@ -34,6 +34,7 @@ commands=
     native-blockchain-constantinople: pytest {posargs:tests/json-fixtures/test_blockchain.py --fork Constantinople}
     native-blockchain-petersburg: pytest {posargs:tests/json-fixtures/test_blockchain.py --fork ConstantinopleFix}
     native-blockchain-istanbul: pytest {posargs:tests/json-fixtures/test_blockchain.py --fork Istanbul}
+    native-blockchain-berlin: pytest {posargs:tests/json-fixtures/test_blockchain.py --fork Berlin}
     native-blockchain-metropolis: pytest {posargs:tests/json-fixtures/test_blockchain.py --fork Metropolis}
     native-blockchain-transition: pytest {posargs:tests/json-fixtures/test_blockchain.py -k BlockchainTests/TransitionTests}
     lint: flake8 {toxinidir}/eth {toxinidir}/tests {toxinidir}/scripts