From db292502567c67b9cec08d8d19bbde6ae8ab6aad Mon Sep 17 00:00:00 2001
From: Hsiao-Wei Wang <hwwang156@gmail.com>
Date: Thu, 1 Aug 2019 14:22:01 +0800
Subject: [PATCH] Add testing helpers

---
 .../test/helpers/phase1/attestations.py       | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 test_libs/pyspec/eth2spec/test/helpers/phase1/attestations.py

diff --git a/test_libs/pyspec/eth2spec/test/helpers/phase1/attestations.py b/test_libs/pyspec/eth2spec/test/helpers/phase1/attestations.py
new file mode 100644
index 000000000..750ab5048
--- /dev/null
+++ b/test_libs/pyspec/eth2spec/test/helpers/phase1/attestations.py
@@ -0,0 +1,37 @@
+from eth2spec.test.helpers.keys import privkeys
+from eth2spec.utils.bls import (
+    bls_aggregate_signatures,
+    bls_sign,
+)
+
+
+def sign_shard_attestation(spec, shard_state, beacon_state, block, participants):
+    signatures = []
+    message_hash = block.core.parent_root
+    block_epoch = spec.compute_epoch_of_shard_slot(block.core.slot)
+    for validator_index in participants:
+        privkey = privkeys[validator_index]
+        signatures.append(
+            get_attestation_signature(
+                spec,
+                shard_state,
+                beacon_state,
+                message_hash,
+                block_epoch,
+                privkey,
+            )
+        )
+
+    return bls_aggregate_signatures(signatures)
+
+
+def get_attestation_signature(spec, shard_state, beacon_state, message_hash, block_epoch, privkey):
+    return bls_sign(
+        message_hash=message_hash,
+        privkey=privkey,
+        domain=spec.get_domain(
+            state=beacon_state,
+            domain_type=spec.DOMAIN_SHARD_ATTESTER,
+            message_epoch=block_epoch,
+        )
+    )