fix(forks,fw): Fix transition forks on state tests (#406)

* fix(forks,fw): Fix transition forks on state tests

* changelog

docs/CHANGELOG.md

@@ -4,6 +4,18 @@ Test fixtures for use by clients are available for each release on the [Github r
 
 **Key:** ✨ = New, 🐞 = Fixed, 🔀 = Changed, 💥 = Breaking change.
 
+## [v2.0.1](https://github.com/ethereum/execution-spec-tests/releases/tag/v2.0.1) - 20XX-XX-XX: Unreleased
+
+### 🧪 Test Cases
+
+### 🛠️ Framework
+
+- 🐞 State tests generated with transition forks no longer use the transition fork name in the fixture output, instead they use the actual enabled fork according to the state test's block number and timestamp ([#406](https://github.com/ethereum/execution-spec-tests/pull/406)).
+
+### 📋 Misc
+
+### 💥 Breaking Changes
+
 ## [v2.0.0](https://github.com/ethereum/execution-spec-tests/releases/tag/v2.0.0) - 2024-01-25: 🐍🏖️ Cancun
 
 Release [v2.0.0](https://github.com/ethereum/execution-spec-tests/releases/tag/v2.0.0) contains many important framework changes, including introduction of the `StateTest` format, and some additional Cancun and other test coverage.

src/ethereum_test_forks/base_fork.py

@@ -234,6 +234,14 @@ def name(cls) -> str:
         """
         return cls.__name__
 
+    @classmethod
+    def fork_at(cls, block_number: int = 0, timestamp: int = 0) -> Type["BaseFork"]:
+        """
+        Returns the fork at the given block number and timestamp.
+        Useful only for transition forks, and it's a no-op for normal forks.
+        """
+        return cls
+
     @classmethod
     @abstractmethod
     def transition_tool_name(cls, block_number: int = 0, timestamp: int = 0) -> str:

src/ethereum_test_forks/tests/test_forks.py

@@ -54,6 +54,13 @@ def test_transition_forks():
     assert ParisToShanghaiAtTime15k.engine_new_payload_version(0, 14_999) == 1
     assert ParisToShanghaiAtTime15k.engine_new_payload_version(0, 15_000) == 2
 
+    assert BerlinToLondonAt5.fork_at(4, 0) == Berlin
+    assert BerlinToLondonAt5.fork_at(5, 0) == London
+    assert ParisToShanghaiAtTime15k.fork_at(0, 14_999) == Paris
+    assert ParisToShanghaiAtTime15k.fork_at(0, 15_000) == Shanghai
+    assert ParisToShanghaiAtTime15k.fork_at() == Paris
+    assert ParisToShanghaiAtTime15k.fork_at(10_000_000, 14_999) == Paris
+
 
 def test_forks_from():  # noqa: D103
     assert forks_from(Paris) == [Paris, LAST_DEPLOYED]

src/ethereum_test_forks/transition_base_fork.py

@@ -91,6 +91,9 @@ def transition_method(
 
         NewTransitionClass.transitions_to = lambda: to_fork  # type: ignore
         NewTransitionClass.transitions_from = lambda: from_fork  # type: ignore
+        NewTransitionClass.fork_at = lambda block_number=0, timestamp=0: (  # type: ignore
+            to_fork if block_number >= at_block and timestamp >= at_timestamp else from_fork
+        )
 
         return NewTransitionClass
 

src/ethereum_test_tools/spec/state/state_test.py

@@ -198,6 +198,9 @@ def generate(
         if self.fixture_format in BlockchainTest.fixture_formats():
             return self.generate_blockchain_test().generate(t8n, fork, eips)
         elif self.fixture_format == FixtureFormats.STATE_TEST:
+            # We can't generate a state test fixture that names a transition fork,
+            # so we get the fork at the block number and timestamp of the state test
+            fork = fork.fork_at(Number(self.env.number), Number(self.env.timestamp))
             return self.make_state_test_fixture(t8n, fork, eips)
 
         raise Exception(f"Unknown fixture format: {self.fixture_format}")