test: mempool entry time is persisted

Also, remove the now unused "Mine a single block to get out of IBD".
This was fixed in commit 1111aec.

Author: MarcoFalke

test/functional/mempool_persist.py

@@ -37,9 +37,15 @@
 """
 from decimal import Decimal
 import os
+import time
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal, assert_raises_rpc_error, wait_until
+from test_framework.util import (
+    assert_equal,
+    assert_greater_than_or_equal,
+    assert_raises_rpc_error,
+    wait_until,
+)
 
 
 class MempoolPersistTest(BitcoinTestFramework):
@@ -51,18 +57,13 @@ def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
 
     def run_test(self):
-        chain_height = self.nodes[0].getblockcount()
-        assert_equal(chain_height, 200)
-
-        self.log.debug("Mine a single block to get out of IBD")
-        self.nodes[0].generate(1)
-        self.sync_all()
-
         self.log.debug("Send 5 transactions from node2 (to its own address)")
+        tx_creation_time_lower = int(time.time())
         for i in range(5):
             last_txid = self.nodes[2].sendtoaddress(self.nodes[2].getnewaddress(), Decimal("10"))
         node2_balance = self.nodes[2].getbalance()
         self.sync_all()
+        tx_creation_time_higher = int(time.time())
 
         self.log.debug("Verify that node0 and node1 have 5 transactions in their mempools")
         assert_equal(len(self.nodes[0].getrawmempool()), 5)
@@ -75,6 +76,10 @@ def run_test(self):
         fees = self.nodes[0].getmempoolentry(txid=last_txid)['fees']
         assert_equal(fees['base'] + Decimal('0.00001000'), fees['modified'])
 
+        tx_creation_time = self.nodes[0].getmempoolentry(txid=last_txid)['time']
+        assert_greater_than_or_equal(tx_creation_time, tx_creation_time_lower)
+        assert_greater_than_or_equal(tx_creation_time_higher, tx_creation_time)
+
         self.log.debug("Stop-start the nodes. Verify that node0 has the transactions in its mempool and node1 does not. Verify that node2 calculates its balance correctly after loading wallet transactions.")
         self.stop_nodes()
         # Give this node a head-start, so we can be "extra-sure" that it didn't load anything later
@@ -93,6 +98,9 @@ def run_test(self):
         fees = self.nodes[0].getmempoolentry(txid=last_txid)['fees']
         assert_equal(fees['base'] + Decimal('0.00001000'), fees['modified'])
 
+        self.log.debug('Verify time is loaded correctly')
+        assert_equal(tx_creation_time, self.nodes[0].getmempoolentry(txid=last_txid)['time'])
+
         # Verify accounting of mempool transactions after restart is correct
         self.nodes[2].syncwithvalidationinterfacequeue()  # Flush mempool to wallet
         assert_equal(node2_balance, self.nodes[2].getbalance())