From 0e59c6676a66bf1f0b40bf0eb76c3040da01656f Mon Sep 17 00:00:00 2001
From: Carl Beekhuizen <carl.beek@gmail.com>
Date: Fri, 21 Jun 2019 13:00:42 +0200
Subject: [PATCH] Stop yielding from fork-choie tests

---
 specs/core/0_fork-choice.md                      |  4 ++--
 .../pyspec/eth2spec/test/test_fork_choice.py     | 16 +++++-----------
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/specs/core/0_fork-choice.md b/specs/core/0_fork-choice.md
index eb7c1a579..3d85cf571 100644
--- a/specs/core/0_fork-choice.md
+++ b/specs/core/0_fork-choice.md
@@ -140,14 +140,14 @@ def on_tick(store: Store, time: int) -> None:
 
 ```python
 def on_block(store: Store, block: BeaconBlock) -> None:
+    # Make a copy of the state to avoid mutability issues
+    pre_state = store.states[block.parent_root].copy()
     # Blocks cannot be in the future. If they are, their consideration must be delayed until the are in the past.
     assert store.time >= pre_state.genesis_time + block.slot * SECONDS_PER_SLOT
     # Add new block to the store
     store.blocks[signing_root(block)] = block
     # Check block is a descendant of the finalized block
     assert get_ancestor(store, signing_root(block), store.blocks[store.finalized_root].slot) == store.finalized_root
-    # Check block slot against Unix time
-    pre_state = store.states[block.parent_root].copy()
     # Check the block is valid and compute the post-state
     state = state_transition(pre_state, block)
     # Add new state to the store
diff --git a/test_libs/pyspec/eth2spec/test/test_fork_choice.py b/test_libs/pyspec/eth2spec/test/test_fork_choice.py
index ab1728251..4bc7e8b0a 100644
--- a/test_libs/pyspec/eth2spec/test/test_fork_choice.py
+++ b/test_libs/pyspec/eth2spec/test/test_fork_choice.py
@@ -2,7 +2,7 @@ from typing import List
 
 from eth2spec.utils.ssz.ssz_impl import signing_root, hash_tree_root
 
-from eth2spec.test.context import with_all_phases, spec_state_test
+from eth2spec.test.context import with_all_phases, with_state, bls_switch
 
 from eth2spec.test.helpers.block import build_empty_block_for_next_slot
 from eth2spec.test.helpers.attestations import get_valid_attestation
@@ -10,10 +10,10 @@ from eth2spec.test.helpers.state import next_slot
 
 
 @with_all_phases
-@spec_state_test
+@with_state
+@bls_switch
 def test_basic(spec, state):
     state.latest_block_header = spec.BeaconBlockHeader(body_root=hash_tree_root(spec.BeaconBlockBody()))
-    yield 'pre', state
 
     # Initialization
     store = spec.get_genesis_store(state)
@@ -36,17 +36,14 @@ def test_basic(spec, state):
 
     spec.on_block(store, block)
     assert store.blocks[signing_root(block)] == block
-    yield 'blocks', blocks, List[spec.BeaconBlock]
 
     # TODO: add tests for justified_root and finalized_root
-    yield 'post', state
 
 
 @with_all_phases
-@spec_state_test
+@with_state
+@bls_switch
 def test_on_attestation(spec, state):
-    yield 'pre', state
-
     store = spec.get_genesis_store(state)
     time = 100
     spec.on_tick(store, time)
@@ -54,7 +51,6 @@ def test_on_attestation(spec, state):
     next_slot(spec, state)
 
     attestation = get_valid_attestation(spec, state, slot=1)
-    yield 'attestation', attestation
     indexed_attestation = spec.convert_to_indexed(state, attestation)
     spec.on_attestation(store, attestation)
     assert (
@@ -64,5 +60,3 @@ def test_on_attestation(spec, state):
             root=attestation.data.target_root,
         )
     )
-
-    yield 'post', state