No duplicate vote inserts with mongodb (#1258)

* prevent duplicate vote inserts

bigchaindb/backend/mongodb/schema.py

@@ -100,4 +100,5 @@ def create_votes_secondary_index(conn, dbname):
                                               ASCENDING),
                                              ('node_pubkey',
                                               ASCENDING)],
-                                            name='block_and_voter')
+                                            name='block_and_voter',
+                                            unique=True)

tests/backend/mongodb/test_queries.py

@@ -212,6 +212,7 @@ def test_get_owned_ids(signed_create_tx, user_pk):
 
 
 def test_get_votes_by_block_id(signed_create_tx, structurally_valid_vote):
+    from bigchaindb.common.crypto import generate_key_pair
     from bigchaindb.backend import connect, query
     from bigchaindb.models import Block
     conn = connect()
@@ -219,10 +220,14 @@ def test_get_votes_by_block_id(signed_create_tx, structurally_valid_vote):
     # create and insert a block
     block = Block(transactions=[signed_create_tx])
     conn.db.bigchain.insert_one(block.to_dict())
+
     # create and insert some votes
     structurally_valid_vote['vote']['voting_for_block'] = block.id
     conn.db.votes.insert_one(structurally_valid_vote)
+    # create a second vote under a different key
+    _, pk = generate_key_pair()
     structurally_valid_vote['vote']['voting_for_block'] = block.id
+    structurally_valid_vote['node_pubkey'] = pk
     structurally_valid_vote.pop('_id')
     conn.db.votes.insert_one(structurally_valid_vote)
 
@@ -325,6 +330,19 @@ def test_write_vote(structurally_valid_vote):
     assert vote_db == structurally_valid_vote
 
 
+def test_duplicate_vote_raises_duplicate_key(structurally_valid_vote):
+    from bigchaindb.backend import connect, query
+    from bigchaindb.backend.exceptions import DuplicateKeyError
+    conn = connect()
+
+    # write a vote
+    query.write_vote(conn, structurally_valid_vote)
+
+    # write the same vote a second time
+    with pytest.raises(DuplicateKeyError):
+        query.write_vote(conn, structurally_valid_vote)
+
+
 def test_get_genesis_block(genesis_block):
     from bigchaindb.backend import connect, query
     conn = connect()

tests/db/test_bigchain_api.py

@@ -446,23 +446,6 @@ class TestBigchainApi(object):
         b.write_vote(b.vote(block_3.id, b.get_last_voted_block().id, True))
         assert b.get_last_voted_block().id == block_3.id
 
-    def test_no_vote_written_if_block_already_has_vote(self, b, genesis_block):
-        from bigchaindb.models import Block
-
-        block_1 = dummy_block()
-        b.write_block(block_1)
-
-        b.write_vote(b.vote(block_1.id, genesis_block.id, True))
-        retrieved_block_1 = b.get_block(block_1.id)
-        retrieved_block_1 = Block.from_dict(retrieved_block_1)
-
-        # try to vote again on the retrieved block, should do nothing
-        b.write_vote(b.vote(retrieved_block_1.id, genesis_block.id, True))
-        retrieved_block_2 = b.get_block(block_1.id)
-        retrieved_block_2 = Block.from_dict(retrieved_block_2)
-
-        assert retrieved_block_1 == retrieved_block_2
-
     @pytest.mark.usefixtures('inputs')
     def test_assign_transaction_one_node(self, b, user_pk, user_sk):
         from bigchaindb.backend import query

tests/web/test_votes.py

@@ -27,6 +27,8 @@ def test_get_votes_endpoint(b, client):
 @pytest.mark.bdb
 @pytest.mark.usefixtures('inputs')
 def test_get_votes_endpoint_multiple_votes(b, client):
+    from bigchaindb.common.crypto import generate_key_pair
+
     tx = Transaction.create([b.me], [([b.me], 1)])
     tx = tx.sign([b.me_private])
 
@@ -37,8 +39,12 @@ def test_get_votes_endpoint_multiple_votes(b, client):
     vote_valid = b.vote(block.id, last_block, True)
     b.write_vote(vote_valid)
 
-    # vote the block valid
+    # vote the block invalid
+    # a note can only vote once so we need a new node_pubkey for the second
+    # vote
+    _, pk = generate_key_pair()
     vote_invalid = b.vote(block.id, last_block, False)
+    vote_invalid['node_pubkey'] = pk
     b.write_vote(vote_invalid)
 
     res = client.get(VOTES_ENDPOINT + '?block_id=' + block.id)