Add `test_zeroed_commitment`

tests/core/pyspec/eth2spec/test/deneb/sanity/test_blocks.py

@@ -150,3 +150,23 @@ def test_incorrect_block_hash(spec, state):
 
     yield 'blocks', [signed_block]
     yield 'post', state
+
+
+@with_deneb_and_later
+@spec_state_test
+def test_zeroed_commitment(spec, state):
+    """
+    The blob is invalid, but the commitment is in correct form.
+    """
+    yield 'pre', state
+
+    block = build_empty_block_for_next_slot(spec, state)
+    opaque_tx, _, blob_kzg_commitments, _ = get_sample_opaque_tx(spec, blob_count=1, is_valid_blob=False)
+    assert all(commitment == b'\x00' * 48 for commitment in blob_kzg_commitments)
+    block.body.blob_kzg_commitments = blob_kzg_commitments
+    block.body.execution_payload.transactions = [opaque_tx]
+    block.body.execution_payload.block_hash = compute_el_block_hash(spec, block.body.execution_payload)
+    signed_block = state_transition_and_sign_block(spec, state, block)
+
+    yield 'blocks', [signed_block]
+    yield 'post', state

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

@@ -50,12 +50,9 @@ class SignedBlobTransaction(Container):
     signature: ECDSASignature
 
 
-def get_sample_blob(spec, rng=None):
-    if rng is None:
-        rng = random.Random(5566)
-
+def get_sample_blob(spec, rng=random.Random(5566), is_valid_blob=True):
     values = [
-        rng.randint(0, spec.BLS_MODULUS - 1)
+        rng.randint(0, spec.BLS_MODULUS - 1) if is_valid_blob else spec.BLS_MODULUS
         for _ in range(spec.FIELD_ELEMENTS_PER_BLOB)
     ]
 
@@ -98,15 +95,19 @@ def get_poly_in_both_forms(spec, rng=None):
     return coeffs, evals
 
 
-def get_sample_opaque_tx(spec, blob_count=1, rng=None):
+def get_sample_opaque_tx(spec, blob_count=1, rng=random.Random(5566), is_valid_blob=True):
     blobs = []
     blob_kzg_commitments = []
     blob_kzg_proofs = []
     blob_versioned_hashes = []
     for _ in range(blob_count):
-        blob = get_sample_blob(spec, rng)
-        blob_commitment = spec.KZGCommitment(spec.blob_to_kzg_commitment(blob))
-        blob_kzg_proof = spec.compute_blob_kzg_proof(blob, blob_commitment)
+        blob = get_sample_blob(spec, rng, is_valid_blob=is_valid_blob)
+        if is_valid_blob:
+            blob_commitment = spec.KZGCommitment(spec.blob_to_kzg_commitment(blob))
+            blob_kzg_proof = spec.compute_blob_kzg_proof(blob, blob_commitment)
+        else:
+            blob_commitment = spec.KZGCommitment()
+            blob_kzg_proof = spec.KZGProof()
         blob_versioned_hash = spec.kzg_commitment_to_versioned_hash(blob_commitment)
         blobs.append(blob)
         blob_kzg_commitments.append(blob_commitment)