diff --git a/pysetup/spec_builders/deneb.py b/pysetup/spec_builders/deneb.py
index b4e180c2a..c32bee830 100644
--- a/pysetup/spec_builders/deneb.py
+++ b/pysetup/spec_builders/deneb.py
@@ -21,9 +21,9 @@ T = TypeVar('T')  # For generic function
     @classmethod
     def sundry_functions(cls) -> str:
         return '''
-def retrieve_blobs_and_proofs(beacon_block_root: Root) -> PyUnion[Tuple[Blob, KZGProof], Tuple[str, str]]:
+def retrieve_blobs_and_proofs(beacon_block_root: Root) -> Tuple[Sequence[Blob], Sequence[KZGProof]]:
     # pylint: disable=unused-argument
-    return ("TEST", "TEST")'''
+    return [], []'''
 
     @classmethod
     def execution_engine_cls(cls) -> str:
diff --git a/specs/deneb/fork-choice.md b/specs/deneb/fork-choice.md
index 23eef436c..2805fd146 100644
--- a/specs/deneb/fork-choice.md
+++ b/specs/deneb/fork-choice.md
@@ -55,11 +55,6 @@ def is_data_available(beacon_block_root: Root, blob_kzg_commitments: Sequence[KZ
     # `MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS`
     blobs, proofs = retrieve_blobs_and_proofs(beacon_block_root)
 
-    # For testing, `retrieve_blobs_and_proofs` returns ("TEST", "TEST").
-    # TODO: Remove it once we have a way to inject `BlobSidecar` into tests.
-    if isinstance(blobs, str) or isinstance(proofs, str):
-        return True
-
     return verify_blob_kzg_proof_batch(blobs, blob_kzg_commitments, proofs)
 ```
 
diff --git a/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py b/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py
index d73a9a01b..c3f496a49 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py
@@ -10,11 +10,18 @@ from eth2spec.test.helpers.attestations import (
 
 
 class BlobData(NamedTuple):
+    """
+    The return values of ``retrieve_blobs_and_proofs`` helper.
+    """
     blobs: Sequence[Any]
     proofs: Sequence[bytes]
 
 
 def with_blob_data(spec, blob_data, func):
+    """
+    This helper runs the given ``func`` with monkeypatched ``retrieve_blobs_and_proofs``
+    that returns ``blob_data.blobs, blob_data.proofs``.
+    """
     def retrieve_blobs_and_proofs(beacon_block_root):
         return blob_data.blobs, blob_data.proofs