run process yield-from test pattern

test_libs/pyspec/eth2spec/test/epoch_processing/test_process_registry_updates.py

@@ -5,10 +5,34 @@ from eth2spec.phase0.spec import (
     is_active_validator,
     process_registry_updates
 )
+from eth2spec.phase0.state_transition import state_transition
+from eth2spec.test.helpers.block import build_empty_block_for_next_slot, sign_block
 from eth2spec.test.helpers.state import next_epoch
 from eth2spec.test.context import spec_state_test
 
 
+def run_process_registry_updates(state, valid=True):
+    """
+    Run ``process_crosslinks``, yielding:
+      - pre-state ('pre')
+      - post-state ('post').
+    If ``valid == False``, run expecting ``AssertionError``
+    """
+    # transition state to slot before state transition
+    slot = state.slot + (spec.SLOTS_PER_EPOCH - state.slot % spec.SLOTS_PER_EPOCH) - 1
+    block = build_empty_block_for_next_slot(state, signed=False)
+    block.slot = slot
+    sign_block(state, block)
+    state_transition(state, block)
+
+    # cache state before epoch transition
+    spec.cache_state(state)
+
+    yield 'pre', state
+    process_registry_updates(state)
+    yield 'post', state
+
+
 @spec_state_test
 def test_activation(state):
     index = 0
@@ -23,11 +47,7 @@ def test_activation(state):
     for _ in range(spec.ACTIVATION_EXIT_DELAY + 1):
         next_epoch(state)
 
-    yield 'pre', state
+    yield from run_process_registry_updates(state)
-
-    process_registry_updates(state)
-
-    yield 'post', state
 
     assert state.validator_registry[index].activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
     assert state.validator_registry[index].activation_epoch != spec.FAR_FUTURE_EPOCH
@@ -49,11 +69,7 @@ def test_ejection(state):
     for _ in range(spec.ACTIVATION_EXIT_DELAY + 1):
         next_epoch(state)
 
-    yield 'pre', state
+    yield from run_process_registry_updates(state)
-
-    process_registry_updates(state)
-
-    yield 'post', state
 
     assert state.validator_registry[index].exit_epoch != spec.FAR_FUTURE_EPOCH
     assert not is_active_validator(