add double spend test, fix double spend validation

bigchaindb/backend/localmongodb/query.py

@@ -55,7 +55,7 @@ def get_spent(conn, transaction_id, output):
     try:
         return conn.run(
             conn.collection('transactions')
-            .find_one({'id': transaction_id,
+            .find_one({'inputs.fulfills.transaction_id': transaction_id,
                        'inputs.fulfills.output_index': output},
                       {'_id': 0}))
     except IndexError:

bigchaindb/tendermint/lib.py

@@ -68,7 +68,19 @@ class BigchainDB(Bigchain):
     def get_spent(self, txid, output):
         transaction = backend.query.get_spent(self.connection, txid,
                                               output)
-        return Transaction.from_dict(transaction)
+        if transaction and transaction['operation'] == 'CREATE':
+            asset = backend.query.get_asset(self.connection, transaction['id'])
+
+            if asset:
+                transaction['asset'] = asset
+            else:
+                transaction['asset'] = {'data': None}
+
+            return Transaction.from_dict(transaction)
+        elif transaction and transaction['operation'] == 'TRANSFER':
+            return Transaction.from_dict(transaction)
+        else:
+            return None
 
     def store_block(self, block):
         """Create a new block."""

tests/tendermint/test_core.py

@@ -74,3 +74,44 @@ def test_deliver_tx__double_spend_fails(b):
     assert b.get_transaction(tx.id).id == tx.id
     result = app.deliver_tx(encode_tx_to_bytes(tx))
     assert result.is_error()
+
+def test_deliver_transfer_tx__double_spend_fails(b):
+    from bigchaindb.tendermint import App
+    from bigchaindb.models import Transaction
+    from bigchaindb.common.crypto import generate_key_pair
+    from bigchaindb.common.transaction import Input
+
+    alice = generate_key_pair()
+    bob = generate_key_pair()
+    carly = generate_key_pair()
+
+    asset = {
+        "msg": "live long and prosper"
+    }
+
+    tx = Transaction.create([alice.public_key],
+                            [([alice.public_key], 1)],
+                            asset = asset)\
+                    .sign([alice.private_key])
+
+    app = App(b)
+    result = app.deliver_tx(encode_tx_to_bytes(tx))
+    assert result.is_ok()
+
+    tx_transfer = Transaction.transfer(tx.to_inputs(),
+                            [([bob.public_key], 1)],
+                            asset_id = tx.id)\
+                    .sign([alice.private_key])
+
+    app = App(b)
+    result = app.deliver_tx(encode_tx_to_bytes(tx_transfer))
+    assert result.is_ok()
+
+    double_spend = Transaction.transfer(tx.to_inputs(),
+                            [([carly.public_key], 1)],
+                            asset_id = tx.id)\
+                    .sign([alice.private_key])
+
+    app = App(b)
+    result = app.deliver_tx(encode_tx_to_bytes(double_spend))
+    assert result.is_error()