Output attester_slashing data to fork choice test vectors

tests/core/pyspec/eth2spec/test/helpers/fork_choice.py

@@ -92,6 +92,10 @@ def get_attestation_file_name(attestation):
     return f"attestation_{encode_hex(attestation.hash_tree_root())}"
 
 
+def get_attester_slashing_file_name(attester_slashing):
+    return f"attester_slashing_{encode_hex(attester_slashing.hash_tree_root())}"
+
+
 def on_tick_and_append_step(spec, store, time, test_steps):
     spec.on_tick(store, time)
     test_steps.append({'tick': int(time)})
@@ -142,6 +146,10 @@ def add_block(spec,
     for attestation in signed_block.message.body.attestations:
         run_on_attestation(spec, store, attestation, is_from_block=True, valid=True)
 
+    # An on_block step implies receiving block's attester slashings
+    for attester_slashing in signed_block.message.body.attester_slashings:
+        run_on_attester_slashing(spec, store, attester_slashing, valid=True)
+
     block_root = signed_block.message.hash_tree_root()
     assert store.blocks[block_root] == signed_block.message
     assert store.block_states[block_root].hash_tree_root() == signed_block.message.state_root
@@ -168,6 +176,38 @@ def add_block(spec,
     return store.block_states[signed_block.message.hash_tree_root()]
 
 
+def run_on_attester_slashing(spec, store, attester_slashing, valid=True):
+    if not valid:
+        try:
+            spec.on_attester_slashing(store, attester_slashing)
+        except AssertionError:
+            return
+        else:
+            assert False
+
+    spec.on_attester_slashing(store, attester_slashing)
+
+
+def add_attester_slashing(spec, store, attester_slashing, test_steps, valid=True):
+    slashing_file_name = get_attester_slashing_file_name(attester_slashing)
+    yield get_attester_slashing_file_name(attester_slashing), attester_slashing
+
+    if not valid:
+        try:
+            run_on_attester_slashing(spec, store, attester_slashing)
+        except AssertionError:
+            test_steps.append({
+                'attester_slashing': slashing_file_name,
+                'valid': False,
+            })
+            return
+        else:
+            assert False
+
+    run_on_attester_slashing(spec, store, attester_slashing)
+    test_steps.append({'attester_slashing': slashing_file_name})
+
+
 def get_formatted_head_output(spec, store):
     head = spec.get_head(store)
     slot = store.blocks[head].slot

tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py

@@ -8,24 +8,27 @@
     with_presets,
 )
 from eth2spec.test.helpers.attestations import get_valid_attestation, next_epoch_with_attestations
-from eth2spec.test.helpers.block import build_empty_block_for_next_slot
+from eth2spec.test.helpers.block import (
+    apply_empty_block,
+    build_empty_block_for_next_slot,
+)
 from eth2spec.test.helpers.constants import MINIMAL
 from eth2spec.test.helpers.fork_choice import (
-    tick_and_run_on_attestation,
-    tick_and_add_block,
+    add_attester_slashing,
+    add_block,
     get_anchor_root,
     get_genesis_forkchoice_store_and_block,
     get_formatted_head_output,
     on_tick_and_append_step,
-    add_block,
+    run_on_attestation,
+    tick_and_run_on_attestation,
+    tick_and_add_block,
 )
 from eth2spec.test.helpers.state import (
     next_slots,
     next_epoch,
     state_transition_and_sign_block,
 )
-from tests.core.pyspec.eth2spec.test.helpers.block import apply_empty_block
-from tests.core.pyspec.eth2spec.test.helpers.fork_choice import run_on_attestation
 
 
 rng = random.Random(1001)
@@ -411,7 +414,7 @@ def test_discard_equivocations(spec, state):
 
     # Process attester_slashing
     # The head should revert to block_2
-    spec.on_attester_slashing(store, attester_slashing)
+    yield from add_attester_slashing(spec, store, attester_slashing, test_steps)
     assert spec.get_head(store) == spec.hash_tree_root(block_2)
 
     test_steps.append({

tests/formats/fork_choice/README.md

@@ -76,11 +76,27 @@ Adds `PowBlock` data which is required for executing `on_block(store, block)`.
 {
     pow_block: string  -- the name of the `pow_block_<32-byte-root>.ssz_snappy` file.
                           To be used in `get_pow_block` lookup
-}  
+}
 ```
 The file is located in the same folder (see below).
 PowBlocks should be used as return values for `get_pow_block(hash: Hash32) -> PowBlock` function if hashes match.
 
+#### `on_attester_slashing` execution step
+
+The parameter that is required for executing `on_attester_slashing(store, attester_slashing)`.
+
+```yaml
+{
+    attester_slashing: string  -- the name of the `attester_slashing_<32-byte-root>.ssz_snappy` file.
+                            To execute `on_attester_slashing(store, attester_slashing)` with the given attester slashing.
+    valid: bool          -- optional, default to `true`.
+                            If it's `false`, this execution step is expected to be invalid.
+}
+```
+The file is located in the same folder (see below).
+
+After this step, the `store` object may have been updated.
+
 #### Checks step
 
 The checks to verify the current status of `store`.