pytest: test to show that listpays doesn't remember bolt11 string.

[Separated into separate commit by RR]

tests/test_pay.py

@@ -3193,3 +3193,27 @@ def test_pay_fail_unconfirmed_channel(node_factory, bitcoind):
 
     # Now l1 can pay to l2.
     l1.rpc.pay(invl2)
+
+
+@pytest.mark.xfail(strict=True)    
+def test_bolt11_null_after_pay(node_factory, bitcoind):
+    l1, l2 = node_factory.get_nodes(2)
+
+    amount_sat = 10 ** 6
+    # pay a generic bolt11 and test if the label bol11 is null
+    # inside the command listpays
+
+    # create l2->l1 channel.
+    l2.fundwallet(amount_sat * 5)
+    l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
+    l2.rpc.fundchannel(l1.info['id'], amount_sat * 3)
+
+    # Let the channel confirm.
+    bitcoind.generate_block(6)
+    sync_blockheight(bitcoind, [l1, l2])
+
+    invl1 = l1.rpc.invoice(Millisatoshi(amount_sat * 2 * 1000), 'j', 'j')['bolt11']
+    l2.rpc.pay(invl1)
+
+    pays = l2.rpc.listpays()["pays"]
+    assert pays[0]["bolt11"] == invl1