Emit checks after each individual test step

Co-authored-by: Hsiao-Wei Wang <hsiaowei.eth@gmail.com>

tests/core/pyspec/eth2spec/test/altair/sync_protocol/test_light_client_sync.py

@@ -45,8 +45,6 @@ def setup_test(spec, state):
 
 def finish_test(test):
     yield "steps", test.steps
-    yield "expected_finalized_header", test.store.finalized_header
-    yield "expected_optimistic_header", test.store.optimistic_header
 
 
 def get_update_file_name(spec, update):
@@ -61,15 +59,30 @@ def get_update_file_name(spec, update):
     return f"update_{encode_hex(update.attested_header.hash_tree_root())}_{suffix1}{suffix2}"
 
 
+def get_checks(store):
+    return {
+        "finalized_header": {
+            'slot': int(store.finalized_header.slot),
+            'root': encode_hex(store.finalized_header.hash_tree_root()),
+        },
+        "optimistic_header": {
+            'slot': int(store.optimistic_header.slot),
+            'root': encode_hex(store.optimistic_header.hash_tree_root()),
+        },
+    }
+
+
 def emit_slot(test, spec, state):
     current_slot = state.slot
-    yield from []
+    spec.process_slot_for_light_client_store(test.store, current_slot)
+
+    yield from []  # Consistently enable `yield from` syntax in calling tests
     test.steps.append({
         "process_slot": {
             "current_slot": int(current_slot),
+            "checks": get_checks(test.store),
         }
     })
-    spec.process_slot_for_light_client_store(test.store, current_slot)
 
 
 def emit_update(test, spec, state, block, attested_state, finalized_block, with_next_sync_committee=True):
@@ -79,14 +92,16 @@ def emit_update(test, spec, state, block, attested_state, finalized_block, with_
         update.next_sync_committee_branch = \
             [spec.Bytes32() for _ in range(spec.floorlog2(spec.NEXT_SYNC_COMMITTEE_INDEX))]
     current_slot = state.slot
+    spec.process_light_client_update(test.store, update, current_slot, test.genesis_validators_root)
+
     yield get_update_file_name(spec, update), update
     test.steps.append({
         "process_update": {
             "update": get_update_file_name(spec, update),
             "current_slot": int(current_slot),
+            "checks": get_checks(test.store),
         }
     })
-    spec.process_light_client_update(test.store, update, current_slot, test.genesis_validators_root)
     return update
 
 

tests/formats/sync_protocol/light_client_sync.md

@@ -17,7 +17,22 @@ An SSZ-snappy encoded `bootstrap` object of type `LightClientBootstrap` to initi
 
 ### `steps.yaml`
 
-The steps to execute in sequence. There may be multiple items of the following types:
+The steps to execute in sequence.
+
+#### `checks` execution step
+
+Each step includes checks to verify the expected impact on the `store` object.
+
+```yaml
+finalized_header: {
+    slot: int,                -- Integer value from store.finalized_header.slot
+    root: string,             -- Encoded 32-byte value from store.finalized_header.hash_tree_root()
+}
+optimistic_header: {
+    slot: int,                -- Integer value from store.optimistic_header.slot
+    root: string,             -- Encoded 32-byte value from store.optimistic_header.hash_tree_root()
+}
+```
 
 #### `process_slot` execution step
 
@@ -26,7 +41,8 @@ should be executed with the specified parameters:
 
 ```yaml
 {
-    current_slot: int  -- integer, decimal
+    current_slot: int                  -- integer, decimal
+    checks: {<store_attibute>: value}  -- the assertions.
 }
 ```
 
@@ -38,22 +54,15 @@ The function `process_light_client_update(store, update, current_slot, genesis_v
 
 ```yaml
 {
-    update: string             -- name of the `*.ssz_snappy` file to load
-                                  as a `LightClientUpdate` object
-    current_slot: int          -- integer, decimal
+    update: string                     -- name of the `*.ssz_snappy` file to load
+                                          as a `LightClientUpdate` object
+    current_slot: int                  -- integer, decimal
+    checks: {<store_attibute>: value}  -- the assertions.
 }
 ```
 
 After this step, the `store` object may have been updated.
 
-### `expected_finalized_header.ssz_snappy`
-
-An SSZ-snappy encoded `expected_finalized_header` object of type `BeaconBlockHeader` that represents the expected `store.finalized_header` after applying all the test steps.
-
-### `expected_optimistic_header.ssz_snappy`
-
-An SSZ-snappy encoded `expected_optimistic_header` object of type `BeaconBlockHeader` that represents the expected `store.finalized_header` after applying all the test steps.
-
 ## Condition
 
-A test-runner should initialize a local `LightClientStore` using the provided `bootstrap` object. It should then proceed to execute all the test steps in sequence. Finally, it should verify that the resulting `store` refers to the provided `expected_finalized_header` and `expected_optimistic_header`.
+A test-runner should initialize a local `LightClientStore` using the provided `bootstrap` object. It should then proceed to execute all the test steps in sequence. After each step, it should verify that the resulting `store` verifies against the provided `checks`.