lntest+itest: make sure mempool is cleaned in watcher tower test

This commit adds the missing check for anchor sweep in test
`revoked_uncooperative_close_retribution_altruist_watchtower`, also
change the mempool check a bit so it's easier to track.

lntemp/harness.go

@@ -349,10 +349,6 @@ func (h *HarnessTest) Subtest(t *testing.T) *HarnessTest {
 			return
 		}
 
-		// We require the mempool to be cleaned from the test.
-		require.Empty(st, st.Miner.GetRawMempool(), "mempool not "+
-			"cleaned, please mine blocks to clean them all.")
-
 		// When we finish the test, reset the nodes' configs and take a
 		// snapshot of each of the nodes' internal states.
 		for _, node := range st.manager.standbyNodes {
@@ -362,8 +358,9 @@ func (h *HarnessTest) Subtest(t *testing.T) *HarnessTest {
 		// If found running nodes, shut them down.
 		st.shutdownNonStandbyNodes()
 
-		// Assert that mempool is cleaned
+		// We require the mempool to be cleaned from the test.
-		st.Miner.AssertNumTxsInMempool(0)
+		require.Empty(st, st.Miner.GetRawMempool(), "mempool not "+
+			"cleaned, please mine blocks to clean them all.")
 
 		// Finally, cancel the run context. We have to do it here
 		// because we need to keep the context alive for the above

lntest/itest/lnd_revocation_test.go

@@ -849,6 +849,11 @@ func testRevokedCloseRetributionAltruistWatchtowerCase(ht *lntemp.HarnessTest,
 
 	ht.AssertNumPendingForceClose(dave, 0)
 
+	// If this is an anchor channel, Dave would sweep the anchor.
+	if anchors {
+		ht.MineBlocksAndAssertNumTxes(1, 1)
+	}
+
 	// Check that Dave's wallet balance is increased.
 	err = wait.NoError(func() error {
 		daveBalResp := dave.RPC.WalletBalance()