test: Speed up mempool_spend_coinbase.py

Author: MarcoFalke

test/functional/mempool_spend_coinbase.py

@@ -20,41 +20,41 @@
 class MempoolSpendCoinbaseTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
-        self.setup_clean_chain = True
 
     def run_test(self):
         wallet = MiniWallet(self.nodes[0])
 
-        wallet.generate(200)
-        chain_height = self.nodes[0].getblockcount()
-        assert_equal(chain_height, 200)
+        # Invalidate two blocks, so that miniwallet has access to a coin that will mature in the next block
+        chain_height = 198
+        self.nodes[0].invalidateblock(self.nodes[0].getblockhash(chain_height + 1))
+        assert_equal(chain_height, self.nodes[0].getblockcount())
 
         # Coinbase at height chain_height-100+1 ok in mempool, should
         # get mined. Coinbase at height chain_height-100+2 is
         # too immature to spend.
-        b = [self.nodes[0].getblockhash(n) for n in range(101, 103)]
-        coinbase_txids = [self.nodes[0].getblock(h)['tx'][0] for h in b]
-        utxo_101 = wallet.get_utxo(txid=coinbase_txids[0])
-        utxo_102 = wallet.get_utxo(txid=coinbase_txids[1])
+        wallet.scan_blocks(start=chain_height - 100 + 1, num=1)
+        utxo_mature = wallet.get_utxo()
+        wallet.scan_blocks(start=chain_height - 100 + 2, num=1)
+        utxo_immature = wallet.get_utxo()
 
-        spend_101_id = wallet.send_self_transfer(from_node=self.nodes[0], utxo_to_spend=utxo_101)["txid"]
+        spend_mature_id = wallet.send_self_transfer(from_node=self.nodes[0], utxo_to_spend=utxo_mature)["txid"]
 
-        # coinbase at height 102 should be too immature to spend
-        immature_tx = wallet.create_self_transfer(from_node=self.nodes[0], utxo_to_spend=utxo_102, mempool_valid=False)
+        # other coinbase should be too immature to spend
+        immature_tx = wallet.create_self_transfer(from_node=self.nodes[0], utxo_to_spend=utxo_immature, mempool_valid=False)
         assert_raises_rpc_error(-26,
                                 "bad-txns-premature-spend-of-coinbase",
                                 lambda: self.nodes[0].sendrawtransaction(immature_tx['hex']))
 
-        # mempool should have just spend_101:
-        assert_equal(self.nodes[0].getrawmempool(), [spend_101_id])
+        # mempool should have just the mature one
+        assert_equal(self.nodes[0].getrawmempool(), [spend_mature_id])
 
-        # mine a block, spend_101 should get confirmed
+        # mine a block, mature one should get confirmed
         self.nodes[0].generate(1)
         assert_equal(set(self.nodes[0].getrawmempool()), set())
 
-        # ... and now height 102 can be spent:
-        spend_102_id = self.nodes[0].sendrawtransaction(immature_tx['hex'])
-        assert_equal(self.nodes[0].getrawmempool(), [spend_102_id])
+        # ... and now previously immature can be spent:
+        spend_new_id = self.nodes[0].sendrawtransaction(immature_tx['hex'])
+        assert_equal(self.nodes[0].getrawmempool(), [spend_new_id])
 
 
 if __name__ == '__main__':